Product Guides
Stay Cool, Stay Productive: A Guide to Working in Hot Conditions
Summer is here, and with it comes the risk of heat-related illnesses. Learn how to stay safe and productive during extreme heat.
Read moreProduct Guides
Drill Bit Size Chart: Metric, Imperial & Fractional
Drill Bit Selector — Most-Asked Sizes This page is a working selector tool — not just a reference. Use it to get the right drill bit into your hand in one click. The 10 most-asked drill sizes at AIMS are below. For less common sizes, scroll to the full conversion chart further down. How to use: 1. Find your drill size 2. Click Buy drill 3. Confirm material match using the "By Material" section below 3 mm HSS jobber drill Buy drill → 4 mm HSS jobber drill Buy drill → 5 mm HSS jobber drill Buy drill → 6 mm HSS jobber drill Buy drill → 6.5 mm HSS jobber drill Buy drill → 8 mm HSS jobber drill Buy drill → 10 mm HSS jobber drill Buy drill → 12 mm HSS jobber drill Buy drill → 13 mm HSS jobber drill Buy drill → 16 mm HSS jobber drill Buy drill → Default recommendation: Sutton D101 Silver Bullet HSS jobber drill — the workshop standard for occasional drilling in mild steel, aluminium, plastics and timber. For production steel work switch to D102 Blue Bullet (steam oxide finish). For stainless steel or hardened material, use D108 or D109 cobalt drill bits. For concrete and masonry, use D600 / D601 TCT masonry drill bits (linked in the Anchor Bolt sections below). Need help? Call us on (02) 9773 0122. Jump to: Quick Reference Full Conversion Chart By Material Anchor Bolt Sizes Related Selectors Imperial Drill Bit Sizes in Millimetres — Quick Reference The fastest way to convert a fractional or imperial drill bit size to millimetres is the constant 25.4 mm per inch. So 1/8" = 3.175 mm, 5/32" = 3.969 mm, 3/16" = 4.763 mm, 7/32" = 5.556 mm, 1/4" = 6.350 mm, 5/16" = 7.938 mm, 3/8" = 9.525 mm and 15/64" = 5.953 mm. The full metric, imperial and fractional cross-reference chart sits in the body below. What size is a 1/8" drill bit in mm? 1/8" equals 3.175 mm exactly (1 ÷ 8 × 25.4). The closest standard metric drill bit is 3.2 mm. What size is a 3/16" drill bit in mm? 3/16" equals 4.763 mm (3 ÷ 16 × 25.4). The closest standard metric drill bits are 4.8 mm or 5.0 mm. What is the standard mm size of a 5/32" drill bit? 5/32" equals 3.969 mm (5 ÷ 32 × 25.4). The closest standard metric drill bit is 4.0 mm. Use this drill bit size chart to cross-reference metric (mm), imperial (fractional and decimal inches), and gauge sizes — including number and letter — in a single reference table. Whether you're sizing a pilot hole for a screw or bolt, converting between measurement systems, or identifying an unmarked bit, find your size below and read across the row for the equivalent. Quick conversion — most-searched sizes Imperial to metric: 1/8" = 3.175mm · 5/32" = 3.97mm · 3/16" = 4.76mm · 7/32" = 5.56mm · 1/4" = 6.35mm · 5/16" = 7.94mm · 3/8" = 9.525mm · 7/16" = 11.11mm · 1/2" = 12.7mm · 9/16" = 14.29mm · 5/8" = 15.88mm · 3/4" = 19.05mm · 1" = 25.4mm Metric to imperial: 3mm ≈ 1/8" · 4mm ≈ 5/32" · 5mm ≈ 13/64" · 6mm ≈ 15/64" · 8mm ≈ 5/16" · 10mm ≈ 25/64" · 12mm ≈ 15/32" Full metric / fractional / number / letter cross-reference table below. This guide is part of AIMS Industrial's curated Engineering Reference Charts library — 78 reference articles across fasteners, threading, bearings, lubrication and safety standards. Drill Bit Size Chart — Quick Reference Quick conversion between the most common metric (mm) and imperial (fractional inch) drill bit sizes. Full cross-reference table with number and letter gauge sizes is below. Metric (mm) Fractional Inch Decimal Inch 3.0 mm 1/8" 0.1181 4.0 mm 5/32" 0.1575 5.0 mm 13/64" 0.1969 6.0 mm 15/64" 0.2362 8.0 mm 5/16" 0.3150 10.0 mm 25/64" 0.3937 12.0 mm 15/32" 0.4724 16.0 mm 5/8" 0.6299 20.0 mm 25/32" 0.7874 25.4 mm 1" 1.0000 How to Use This Chart The table covers drill bit sizes from 0.010mm to 25.4mm (1 inch). Find your required hole size in the metric or imperial column and read across to identify the equivalent gauge number, letter, fractional, or decimal size. A few things to keep in mind. Not all metric drill bits have imperial equivalents and vice versa. Some metric values are close enough to share the same imperial counterpart. Values are rounded to the nearest thousandth millimetre or ten-thousandth decimal inch. Need help finding your size? Call AIMS on (02) 9773 0122 — the team can confirm stock and pick the right drill type for your material. Or browse all jobber drill bits. Gauge Sizing Metric / SI Imperial / US Number / Letter Size Millimeters Fractional Inches Fractional Inches (Reduced) Decimal Inches --- 0.010 --- --- 0.0004 104 0.080 --- --- 0.0031 103 0.090 --- --- 0.0035 102 --- --- --- 0.0039 --- 0.100 --- --- 0.0039 101 0.110 --- --- 0.0043 100 0.120 --- --- 0.0047 99 0.130 --- --- 0.0051 98 0.140 --- --- 0.0055 97 0.150 --- --- 0.0059 96 0.160 --- --- 0.0063 95 0.170 --- --- 0.0067 94 0.180 --- --- 0.0071 93 0.190 --- --- 0.0075 --- 0.198 1/128 --- 0.0078 92 0.201 --- --- 0.0079 91 0.210 --- --- 0.0083 90 0.220 --- --- 0.0087 89 0.230 --- --- 0.0091 88 0.240 --- --- 0.0095 --- 0.250 --- --- 0.0098 87 0.254 --- --- 0.0100 --- 0.260 --- --- 0.0102 86 0.270 --- --- 0.0105 85 0.280 --- --- 0.0110 84 0.290 --- --- 0.0115 --- 0.300 --- --- 0.0118 83 0.305 --- --- 0.0120 82 0.318 --- --- 0.0125 81 0.330 --- --- 0.0130 80 0.343 --- --- 0.0135 79 0.368 --- --- 0.0145 --- 0.397 1/64 --- 0.0156 78 0.406 --- --- 0.0160 77 0.457 --- --- 0.0180 --- 0.500 --- --- 0.0197 76 0.508 --- --- 0.0200 75 0.533 --- --- 0.0210 74 0.572 --- --- 0.0225 73 0.610 --- --- 0.0240 72 0.635 --- --- 0.0250 71 0.660 --- --- 0.0260 70 0.710 --- --- 0.0280 69 0.742 --- --- 0.0292 --- 0.750 --- --- 0.0295 68 0.787 --- --- 0.0310 --- 0.794 2/64 1/32 0.0312 67 0.813 --- --- 0.0320 66 0.838 --- --- 0.0330 65 0.889 --- --- 0.0350 64 0.914 --- --- 0.0360 63 0.940 --- --- 0.0370 62 0.965 --- --- 0.0380 61 0.991 --- --- 0.0390 --- 1.000 --- --- 0.0394 60 1.016 --- --- 0.0400 59 1.041 --- --- 0.0410 58 1.067 --- --- 0.0420 57 1.092 --- --- 0.0430 56 1.181 --- --- 0.0465 --- 1.191 3/64 --- 0.0469 --- 1.250 --- --- 0.0492 55 1.321 --- --- 0.0520 54 1.397 --- --- 0.0550 --- 1.500 --- --- 0.0591 53 1.511 --- --- 0.0595 --- 1.588 4/64 1/16 0.0625 52 1.613 --- --- 0.0635 51 1.702 --- --- 0.0670 --- 1.750 --- --- 0.0689 50 1.778 --- --- 0.0700 --- 1.800 --- --- 0.0709 --- 1.850 --- --- 0.0728 49 1.854 --- --- 0.0730 48 1.930 --- --- 0.0760 --- 1.984 5/64 --- 0.0781 47 1.994 --- --- 0.0785 --- 2.000 --- --- 0.0787 46 2.057 --- --- 0.0810 45 2.083 --- --- 0.0820 44 2.184 --- --- 0.0860 --- 2.250 --- --- 0.0886 43 2.261 --- --- 0.0890 42 2.375 --- --- 0.0935 --- 2.381 6/64 3/32 0.0938 41 2.438 --- --- 0.0960 --- 2.450 --- --- 0.0965 40 2.489 --- --- 0.0980 --- 2.500 --- --- 0.0984 39 2.527 --- --- 0.0995 38 2.578 --- --- 0.1015 37 2.642 --- --- 0.1040 36 2.705 --- --- 0.1065 --- 2.750 --- --- 0.1083 --- 2.778 7/64 --- 0.1094 35 2.794 --- --- 0.1100 34 2.819 --- --- 0.1110 33 2.870 --- --- 0.1130 32 2.946 --- --- 0.1160 --- 3.000 --- --- 0.1181 31 3.048 --- --- 0.1200 --- 3.175 8/64 1/8 0.1250 --- 3.250 --- --- 0.1280 30 3.264 --- --- 0.1285 29 3.454 --- --- 0.1360 --- 3.500 --- --- 0.1378 28 3.569 --- --- 0.1405 --- 3.572 9/64 --- 0.1406 27 3.658 --- --- 0.1440 26 3.734 --- --- 0.1470 --- 3.750 --- --- 0.1476 25 3.797 --- --- 0.1495 24 3.861 --- --- 0.1520 23 3.912 --- --- 0.1540 --- 3.969 10/64 5/32 0.1562 22 3.988 --- --- 0.1570 --- 4.000 --- --- 0.1575 21 4.039 --- --- 0.1590 20 4.089 --- --- 0.1610 19 4.216 --- --- 0.1660 --- 4.250 --- --- 0.1673 18 4.305 --- --- 0.1695 --- 4.366 11/64 --- 0.1720 17 4.394 --- --- 0.1730 16 4.496 --- --- 0.1770 --- 4.500 --- --- 0.1772 15 4.572 --- --- 0.1800 14 4.623 --- --- 0.1820 13 4.469 --- --- 0.1850 --- 4.750 --- --- 0.1870 --- 4.763 12/64 3/16 0.1875 12 4.800 --- --- 0.1890 11 4.850 --- --- 0.1910 10 4.915 --- --- 0.1935 9 4.978 --- --- 0.1960 --- 5.000 --- --- 0.1969 8 5.055 --- --- 0.1990 7 5.105 --- --- 0.2010 --- 5.159 13/64 --- 0.2031 6 5.182 --- --- 0.2040 5 5.220 --- --- 0.2055 --- 5.250 --- --- 0.2067 4 5.309 --- --- 0.2090 3 5.410 --- --- 0.2130 --- 5.500 --- --- 0.2165 --- --- 14/64 7/32 0.2188 2 5.613 --- --- 0.2210 --- 5.750 --- --- 0.2264 1 5.791 --- --- 0.2280 A 5.944 --- --- 0.2340 --- 5.953 15/64 --- 0.2344 --- 6.000 --- --- 0.2362 B 6.045 --- --- 0.2380 --- 6.100 --- --- 0.2402 C 6.147 --- --- 0.2420 --- 6.200 --- --- 0.2441 D 6.248 --- --- 0.2460 --- 6.250 --- --- 0.2461 E 6.350 16/64 1/4 0.2500 --- 6.500 --- --- 0.2559 F 6.528 --- --- 0.2570 --- 6.600 --- --- 0.2598 G 6.629 --- --- 0.2610 --- 6.747 17/64 --- 0.2656 --- 6.750 --- --- 0.2657 H 6.756 --- --- 0.2660 --- 6.800 --- --- 0.2677 I 6.909 --- --- 0.2720 --- 7.000 --- --- 0.2756 J 7.036 --- --- 0.2770 --- 7.100 --- --- 0.2795 K 7.137 --- --- 0.2810 --- 7.144 18/64 9/32 0.2813 --- 7.250 --- --- 0.2854 --- 7.300 --- --- 0.2874 L 7.366 --- --- 0.2900 --- 7.400 --- --- 0.2913 M 7.493 --- --- 0.2950 --- 7.500 --- --- 0.2953 --- 7.541 19/64 --- 0.2969 --- 7.600 --- --- 0.2992 N 7.671 --- --- 0.3020 --- 7.750 --- --- 0.3051 --- 7.938 20/64 5/16 0.3125 --- 8.000 --- --- 0.3150 O 8.026 --- --- 0.3160 --- 8.100 --- --- 0.3189 --- 8.200 --- --- 0.3228 P 8.204 --- --- 0.3230 --- 8.250 --- --- 0.3248 --- 8.300 --- --- 0.3268 --- 8.334 21/64 --- 0.3281 Q 8.433 --- --- 0.3320 --- 8.500 --- --- 0.3346 R 8.611 --- --- 0.3390 --- 8.700 --- --- 0.3425 --- 8.731 22/64 11/32 0.3438 --- 8.750 --- --- 0.3445 S 8.839 --- --- 0.3480 --- 9.000 --- --- 0.3543 T 9.093 --- --- 0.3580 --- 9.128 23/64 --- 0.3594 --- 9.250 --- --- 0.3642 U 9.347 --- --- 0.3680 --- 9.500 --- --- 0.3740 --- 9.525 24/64 3/8 0.3750 V 9.576 --- --- 0.3770 --- 9.600 --- --- 0.3780 --- 9.700 --- --- 0.3819 --- 9.750 --- --- 0.3839 --- 9.800 --- --- 0.3858 W 9.804 --- --- 0.3860 --- 9.922 25/64 --- 0.3906 --- 10.000 --- --- 0.3937 X 10.080 --- --- 0.3970 --- 10.084 --- --- 0.4016 Y 10.260 --- --- 0.4040 --- 10.490 26/64 13/32 0.4063 Z 10.490 --- --- 0.4130 --- 10.500 --- --- 0.4134 --- 10.716 27/64 --- 0.4219 --- 11.000 --- --- 0.4331 --- 11.112 28/64 7/16 0.4375 --- 11.500 --- --- 0.4528 --- 11.509 29/64 --- 0.4531 --- 11.906 30/64 15/32 0.4688 --- 12.000 --- --- 0.4724 --- 12.200 --- --- 0.4803 --- 12.303 31/64 --- 0.4844 --- 12.500 --- --- 0.4921 --- 12.700 32/64 1/2 0.5000 --- 12.800 --- --- 0.5039 --- 13.000 --- --- 0.5118 --- 13.097 33/64 --- 0.5156 --- 13.494 34/64 17/32 0.5312 --- 13.500 --- --- 0.5315 --- 13.891 35/64 --- 0.5469 --- 14.000 --- --- 0.5512 --- 14.288 36/64 9/16 0.5625 --- 14.500 --- --- 0.5709 --- 14.684 37/64 --- 0.5781 --- 15.000 --- --- 0.5906 --- 15.081 38/64 19/32 0.5938 --- 15.478 39/64 --- 0.6094 --- 15.500 --- --- 0.6102 --- 15.875 40/64 5/8 0.6250 --- 16.000 --- --- 0.6299 --- 16.272 41/64 --- 0.6406 --- 16.500 --- --- 0.6496 --- 16.669 42/64 21/32 0.6563 --- 17.000 --- --- 0.6693 --- 17.066 43/64 --- 0.6719 --- 17.462 44/64 11/16 0.6875 --- 17.500 --- --- 0.6890 --- 17.859 45/64 --- 0.7031 --- 18.000 --- --- 0.7087 --- 18.256 46/64 23/32 0.7188 --- 18.500 --- --- 0.7283 --- 18.653 47/64 --- 0.7344 --- 19.000 --- --- 0.7480 --- 19.050 48/64 3/4 0.7500 --- 19.447 49/64 --- 0.7656 --- 19.500 --- --- 0.7677 --- 19.844 50/64 25/32 0.7813 --- 20.000 --- --- 0.7874 --- 20.241 51/64 --- 0.7969 --- 20.500 --- --- 0.8071 --- 20.638 52/64 13/16 0.8125 --- 21.000 --- --- 0.8268 --- 21.034 53/64 --- 0.8281 --- 21.431 54/64 27/32 0.8438 --- 21.500 --- --- 0.8465 --- 21.828 55/64 --- 0.8594 --- 22.000 --- --- 0.8661 --- 22.225 56/64 7/8 0.8750 --- 22.500 --- --- 0.8858 --- 22.622 57/64 --- 0.8906 --- 23.000 --- --- 0.9055 --- 23.019 58/64 29/32 0.9062 --- 23.416 59/64 --- 0.9219 --- 23.500 --- --- 0.9252 --- 23.812 60/64 15/16 0.9375 --- 24.000 --- --- 0.9449 --- 24.209 61/64 --- 0.9531 --- 24.500 --- --- 0.9646 --- 24.606 62/64 31/32 0.9688 --- 25.000 --- --- 0.9843 --- 25.003 63/64 --- 0.9844 --- 25.400 64/64 1 1.0000 Understanding Gauge Sizing Gauge sizing directly determines drill bit diameter and affects your selection in three key ways. Precision: the number and letter gauge system offers a high degree of precision for smaller drill bits — critical when exact hole dimensions matter. Compatibility: many fasteners and components are specified by gauge size, so the drill bit must match the gauge of the intended component for a proper fit. Standardisation: gauge sizing provides a consistent method for specifying drill bit dimensions across industries, making communication and cross-referencing straightforward. Selecting the Right Drill Bit The right drill size is not always fixed — it depends on several variables. The material being drilled (steel, aluminium, plastic, timber) affects which size and type of bit to use. The desired thread depth determines the clearance needed for the tap. The required thread fit — close, medium, or free — influences the drill size. Different tap types (taper, plug, bottoming) also require slightly different drill sizes. For fluteless or thread-forming taps specifically, the Engineers Black Book recommends using a good cutting oil or lubricant rather than coolant. If you need complete size data including metric and thread sizes from 0.100mm up to 101.6mm (4 inches), the Engineers Black Book (3rd Edition — Metric) is worth having on hand. Note: this table covers a broad range of sizes but may not include every available drill bit size. Always consult a detailed chart for precision applications. Drill Bit Selection by Material Drilling the right hole isn't just about the diameter — it's about matching the drill bit material and geometry to what you're cutting. The wrong combination means broken bits, oversized holes, work-hardened steel, or burnt edges. Here's what the AIMS workshop crew reaches for: Mild steel (most common) Drill: Sutton D101 Silver Bullet HSS jobber for occasional / hobby work. Sutton D102 Blue Bullet (steam-oxide finish) for production drilling — the oxide finish helps swarf release. Geometry: Standard 118° split point. Lubricant: Any general-purpose cutting fluid or Tap Magic Original. Stainless steel (304, 316) Drill: Cobalt drill bit — Sutton D108 (cobalt jobber, colour-temp tempered) or D109 (heavy duty cobalt bulk pack). The 5-8% cobalt content keeps the drill sharp through stainless's work-hardening. HSS bright drills will glaze the hole, work-harden the steel, and snap. Geometry: 130° to 135° split point preferred (sharper attack angle handles work-hardening better). Lubricant: Tap Magic for Stainless — specifically formulated. Aluminium, brass, copper, plastics Drill: Standard HSS Sutton D101 is fine for most. Sutton D113 Blue Bullet Long Drill for deeper holes. Some users prefer a higher helix angle drill for soft non-ferrous materials to evacuate long stringy chips. Geometry: 130° to 140° point geometry for soft materials. Lubricant: Tap Magic Aluminium variant — prevents the gummy build-up aluminium causes on standard cutting fluids. Cast iron Drill: HSS Sutton D102 Blue Bullet (steam-oxide). Cast iron is brittle and abrasive — the steam oxide finish prolongs drill life. Lubricant: Generally drilled DRY — chips are powder, not strings, so no cutting fluid needed. Hardened steel (above ~30 HRC) For anything above mild steel hardness — pre-hardened tool steels, heat-treated parts, hardfaced surfaces — call AIMS before you start. Solid carbide drills (Sutton D323/D326/D332 series) are the right answer, not HSS or cobalt. Contact us or call (02) 9773 0122 — we'll save you broken drills and damaged workpieces. Concrete, brick, masonry Drill: Tungsten-carbide-tipped (TCT) masonry drill — Sutton D600 (standard fixing, 3mm-13mm) or Sutton D601 (single brick, higher quality, up to 25mm). NOT HSS — HSS bits glaze and dull instantly on concrete. Use: Hammer drill mode required for concrete and brick. Regular rotary drilling on glazed tile only. Lubricant: None — drilled dry. Use a vacuum or compressed air to clear dust as you go. The AIMS workshop rule: Drill speed (RPM) matters more than most beginners realise. Big drill bits need SLOW speeds; small bits need fast. Wrong RPM for the size + material is the #1 cause of drill bit failure. The lathe RPM formula guide covers the maths; the cutting speeds & feeds reference gives you the Vc per material. Anchor Bolt Drill Size Chart Anchor bolts require a hole drilled into concrete, masonry, or brick before installation. The required drill bit size depends on the anchor type — sleeve anchors, wedge anchors, and drop-in anchors each have different requirements. Use a hammer drill or SDS drill with a masonry bit for all concrete anchor applications. Sleeve Anchors & Wedge Anchors (Dynabolts) For sleeve anchors and wedge anchors — including Ramset Dynabolts and equivalent brands — the drill bit diameter matches the anchor diameter. Drill the hole to the specified depth, clear the dust, then drive the anchor. Need help finding your size? Call AIMS on (02) 9773 0122 — the team can confirm stock and pick the right drill type for your material. Or browse masonry drill bits. Anchor Size Drill Bit Size Minimum Hole Depth Typical Application M6 6.0mm 40mm Light fixings, brackets M8 8.0mm 50mm Shelving, light structures M10 10.0mm 60mm Equipment bases, handrails M12 12.0mm 75mm Machinery, structural steel M16 16.0mm 90mm Heavy machinery, posts M20 20.0mm 110mm Structural anchoring M24 24.0mm 125mm Heavy structural anchoring Drop-In Anchors (Internal Thread) Drop-in anchors are flush-mount anchors used where a bolt or threaded rod is inserted after installation. The drill bit size matches the outer body diameter of the anchor — not the internal thread size. Always check the manufacturer's specification for the specific anchor being used, as outer diameters can vary slightly by brand. Internal Thread Drill Bit Size Minimum Hole Depth M6 8.0mm 30mm M8 10.0mm 40mm M10 12.0mm 50mm M12 16.0mm 60mm M16 20.0mm 80mm M20 25.0mm 100mm Chemical Anchors (Resin) Chemical anchors use a two-part resin to bond a threaded rod or rebar into concrete. The drill bit is typically 2–4mm larger than the bar diameter to allow the resin to flow and fully encapsulate the rod. Always follow the anchor manufacturer's specification for hole diameter and depth, as embedment requirements vary by resin system and load rating. Rod / Bar Diameter Drill Bit Size Notes M8 10.0mm Confirm with resin manufacturer M10 12.0mm Confirm with resin manufacturer M12 14.0mm Confirm with resin manufacturer M16 20.0mm Confirm with resin manufacturer M20 24.0mm Confirm with resin manufacturer M24 28.0mm Confirm with resin manufacturer Note: All anchor bolt applications in concrete require a hammer drill or SDS drill with a quality masonry bit. A standard drill will not achieve the required penetration depth or accuracy. Always blow or vacuum dust from the hole before installing the anchor — debris left in the hole reduces holding strength significantly. Related AIMS Selectors & Guides This page sits at the centre of AIMS's drilling tool cluster. The related selectors and selection guides below go deeper on the choices around it: Tap & Drill Bit Selector — Tap Drill Sizes — for threading work, pair this chart with the tap drill sizes Drill Bit Selection Guide — HSS vs cobalt vs carbide, jobber vs stub vs reduced shank vs annular cutter Cobalt Drill Bit Guide — when cobalt is worth the upgrade from HSS HSS vs Carbide End Mill — same material principles apply to drilling decisions Cutting Speeds & Feeds Reference — RPM and feed rate by material and drill diameter Cutting Tool Materials — HSS, cobalt, carbide, PCBN, PCD compared Cutting Tool Coatings — TiN, TiAlN, AlCrN, when each matters for drills Cutting Tool Troubleshooting — walking drills, poor finish, oversize holes, snapped tips Metric / Imperial / Gauge Conversion Master Chart — full drill bit + thread size cross-reference Or browse the full jobber drill bits range + cobalt drill bits — Sutton primary stock, Bordo and P&N alternates, masonry TCT, annular cutters and specialty drilling all in stock for next-day Australia-wide dispatch from our Milperra warehouse.Related Reference Charts Fastener Reference Chart — cross-reference bolt, nut, and screw measurements across metric, Unified Thread Standard, and British Thread Standard values, with thread pitch identification guides. Loctite Grade Selection Guide — identify the right Loctite product for your materials and surfaces. Spanner Size Chart — find the correct spanner or wrench size for your bolt or nut head, metric and imperial. Tapping Drill Size Chart — find the right pilot hole drill size before cutting threads. Covers metric coarse and fine, BSP, UNC, and UNF threads. Frequently Asked Questions What is 3/8 inch drill bit in mm? A 3/8 inch drill bit is 9.525mm. This is one of the most common sizes used for medium pilot holes in steel and timber. What is 1/2 inch drill bit in mm? A 1/2 inch drill bit is 12.7mm exactly. Used for clearance holes on M12 bolts and general large-bore drilling. What is 1/4 inch drill bit in mm? A 1/4 inch drill bit is 6.35mm. Common pilot size for 1/4-20 UNC fasteners and a workshop default for general drilling. What is 5/16 inch drill bit in mm? A 5/16 inch drill bit is 7.94mm — close enough to 8mm for most practical applications, but always use the exact size for precision work. What is 5/8 inch drill bit in mm? A 5/8 inch drill bit is 15.875mm. Used for M16 clearance holes and large structural fixings. What is 9/16 inch drill bit in mm? A 9/16 inch drill bit is 14.288mm. Often used as a clearance hole for 1/2 inch bolts. What is 3/16 inch drill bit in metric? A 3/16 inch drill bit is 4.763mm — close to 4.75mm. Common for light pilot holes in timber and sheet metal. What is 6mm drill bit in imperial? A 6mm drill bit is approximately 15/64 inch (0.2362"). It sits between 15/64" (5.953mm) and 1/4" (6.35mm) — use 6mm where the exact metric size is needed. What is 8mm drill bit in imperial? An 8mm drill bit is approximately 5/16 inch (7.94mm) — they're functionally interchangeable for most general drilling work. What is the order of drill bit sizes? Drill bit sizes run from very small to very large across four overlapping systems: number drills (#80 smallest = 0.343mm, up to #1 = 5.79mm), letter drills (A = 5.94mm up to Z = 10.49mm), fractional inches (1/64" up to 1" and beyond), and metric (typically 0.5mm up to 25mm+). Use the full chart above to cross-reference. What size drill bit do I need for a pilot hole? It depends on the screw or bolt diameter and the material being drilled. As a general rule, size the pilot hole at around 75-85% of the screw's outer diameter for timber, and closer to 90% for metal. For threaded pilot holes, refer to the Tapping Drill Size Chart, which lists the correct drill size for each thread specification. What do number and letter drill bit sizes mean? Number drills (1-80) and letter drills (A-Z) are gauge-based sizing systems used primarily in the USA and in precision engineering. Number sizes run from very small (#80 = 0.343mm) up to #1 (5.791mm), then letter sizes continue from A (5.944mm) through to Z (10.490mm). What are the most common drill bit sizes for general workshop use? For general use in Australia, the most commonly used metric sizes are 3mm, 4mm, 5mm, 6mm, 8mm, and 10mm. These cover most standard fastener pilot holes and everyday drilling tasks. A 13-piece metric set from 1.5mm to 6.5mm in 0.5mm increments is the typical starter kit. Can I substitute a fractional imperial drill bit for a metric size? In most cases yes, provided the sizes are close enough for the application. The chart shows metric and imperial sizes side by side so you can identify the nearest equivalent. For precision work — tight tolerances or threaded holes — always use the exact specified size. What is the largest drill bit size covered in this chart? This chart covers drill bit sizes up to 25.4mm (1 inch / 64/64"). For larger bore sizes, use a spade bit, hole saw, or annular cutter instead of a standard twist drill. Where can I buy drill bits in Australia? AIMS Industrial stocks HSS, cobalt, and carbide drill bits for metal, timber, masonry, and general use, available online with Australia-wide delivery. For complete metric bolt sizing (M3-M24) with thread pitch and head dimensions, see our Metric Bolt Size Guide. People Also Ask — Drill Bit Size Chart: Metric, Imperial & Fractional Q: What size drill bit do I need for an M8 tap? For an M8 × 1.25 coarse thread, use a 6.8 mm drill bit. For M8 × 1.0 fine thread, use a 7.0 mm bit. Always check the specific pitch before drilling — the wrong pilot hole size is the most common cause of tap breakage or stripped threads. Q: How do I convert metric drill bits to imperial? Divide the metric diameter by 25.4 to get inches, or multiply inches by 25.4 to get millimetres. For example, a 10 mm bit equals 0.394" (closest imperial equivalent is 25/64"). A drill bit conversion chart saves calculation errors on the job. Q: What drill bit size is closest to 1/4 inch in metric? A 1/4" drill bit is exactly 6.35 mm. The closest standard metric size is 6.0 mm (slightly under) or 6.5 mm (slightly over). For clearance holes, 6.5 mm is usually the better choice; for tap pilot holes, refer to the thread specification instead. Q: What are the standard drill bit sizes in mm? Standard metric drill bit sets typically cover 1.0–13.0 mm in 0.5 mm steps, with jobber sets often including 0.5–13 mm in 0.1 mm increments. Common sizes for general trade work are 3, 4, 5, 6, 6.5, 8, 10, and 12 mm. Fractional sets cover 1/16" to 1/2" in 1/64" steps. See AIMS's full carbide drill bits range — trade pricing and Australia-wide despatch. Need machining? Browse the AIMS range at machining.
Read more
Loctite Application Guide: Which Grade & When to Use It
Loctite Grade Selector — Match Product to Job This guide is a working Loctite selector. Use the cards below to land on the right grade fast — every grade mentioned in the article body also links to its specific AIMS product page. How to use: 1. Match the job profile (threadlock, sealant, retaining, adhesive) 2. Click the grade to view AIMS stock 3. Use the application section below for technique Low-Strength Threadlock Loctite 222 — small fasteners, removable 222 View → Medium-Strength Threadlock Loctite 243 — workshop default 243 View → High-Strength Threadlock Loctite 263 / 271 — permanent / vibration 263/271 View → Pipe Thread Sealing Loctite 567 / 569 / 577 — anaerobic 567/577 View → Bearing Retaining Loctite 638 / 641 — slip-fit retaining 638 View → Gasket Eliminator Loctite 518 / 510 / 587 / 596 518/596 View → Instant Adhesive (CA) Loctite 401 / 406 / 480 401/406 View → Anti-Seize / Surface Prep Loctite Copper Anti-Seize + 7649 Primer Anti-Seize View → Quick rule of thumb: Loctite anaerobics cure where there's metal + absence of oxygen. Low-strength (222) = removable. Medium-strength (243) = workshop default. High-strength (263/271) = permanent / heat-required to remove. AIMS stocks the full Loctite anaerobic + instant adhesive + sealant + activator range. Need help? Call (02) 9773 0122. Jump to: Which Loctite? Quick Chart Threadlockers Thread Sealants Retaining Anti-Seize Surface Prep Removing Instant Adhesives Related Which Loctite do I use? Loctite threadlockers are colour-coded by strength: blue (Loctite 242 / 243) for medium-strength fasteners you'll need to remove later, red (Loctite 262 / 271 / 277) for permanent high-strength fasteners that stay put, and green (Loctite 290) for wicking into pre-assembled threads. Loctite also makes thread sealants (567 / 577 for tapered pipe threads), retaining compounds (603 / 638 for bearing fits), and instant adhesives (401 / 406 cyanoacrylates). What is Loctite 243 used for? Loctite 243 is a medium-strength blue threadlocker for fasteners between M6 and M20 that you may need to remove later with hand tools. It tolerates light oil contamination on the threads, cures in around 10 minutes to handling strength, and reaches full strength in 24 hours. Typical uses: vehicle suspension bolts, pump and motor fixings, machinery hold-downs, gearbox fasteners. Need another reference chart? Browse the full AIMS Engineering Reference Charts library — drill bit sizes, tap drill, torque, viscosity, GD&T, AS/NZS standards and more. Loctite Quick Selection Chart For threadlocking on small fasteners use Loctite 222 (purple); medium-duty fasteners Loctite 243 (blue); high-strength permanent Loctite 263 or 271 (red). For pipe sealing use Loctite 567 or 577. For retaining compounds use Loctite 638, 641 or 648. Full grade-by-grade detail below. Grade Type / Colour Use For 222 Threadlocker — Purple, low strength Small screws M1.4–M6, grub screws, instruments 243 Threadlocker — Blue, medium strength General fasteners M6–M20, hand-tool removable 263 / 271 Threadlocker — Red, high strength Permanent fasteners — heat required to remove 567 Thread sealant — White Fine hydraulic and pneumatic threads 577 Thread sealant — Yellow BSP and NPT pipe threads, gas, water, oil 638 Retaining compound — High strength Close-tolerance bearing retention 641 Retaining compound — Medium strength Standard bearing / bushing retention 648 Retaining compound — Maximum strength Permanent high-temp cylindrical assemblies 401 Instant adhesive — Cyanoacrylate General-purpose bonding of metal, rubber, plastic 480 Instant adhesive — Toughened CA Impact-resistant rubber and metal bonds What Are Loctite Anaerobic Products? Loctite's industrial range is built on anaerobic chemistry — adhesives and sealants that remain liquid in air but cure rapidly when trapped between two close-fitting metal surfaces in the absence of oxygen. The metal ions in the substrate initiate polymerisation, converting the liquid into a hard thermoset plastic that resists vibration, leakage and corrosion. When stripping a stubborn old anaerobic threadlocker bond, mechanical heat is the standard release method — but for plastic-bodied components where heat is risky, the contrast-cooling trick from our freeze spray guide can shock-fracture cured threadlocker without damaging the surrounding plastic. Quick answer — Loctite grades by job Threadlockers (anaerobic, prevent vibration loosening): 222 low strength (small screws, removable) · 242/243 medium strength (general purpose, blue) · 263/271/277 high strength (permanent, red) · 248 stick form Instant adhesives (cyanoacrylate / super glue): 401 general purpose · 406 rubber/plastic specialty · 414 metals · 480 toughened impact-resistant · 435 low-blooming clear Thread sealants (anaerobic, pipe thread leaks): 567 stainless/coarse (white) · 577 general pipe (yellow, faster cure) · 542 hydraulic fine threads · 545 general purpose Retaining compounds: 603 oil-tolerant · 638 high strength, high temp · 648 high temp, fast cure · 680 slip-fit highest strength This guide covers every industrial Loctite product family relevant to maintenance, engineering and trade work in Australia: threadlockers (preventing fastener loosening under vibration), thread sealants (sealing pipe and hydraulic fittings), and retaining compounds (locking bearings, bushings and cylindrical assemblies). It includes full selection charts, application guides, cure time data, surface preparation requirements and removal instructions — plus a FAQ section that answers the most common grade comparison questions. Browse the full AIMS Industrial Loctite range — threadlockers, thread sealants, retaining compounds and primers stocked for fast Australia-wide dispatch. Loctite Threadlockers: Grades, Colours and Selection Threadlockers prevent fasteners from loosening under vibration, thermal cycling and dynamic load. They fill the microscopic gaps between mating threads, locking out corrosion and sealing against fluid ingress at the same time. Selecting the wrong grade — typically using red where blue is correct, or blue where purple is required — is the most common installation mistake, and can make fasteners impossible to remove without heat or damage the threads on small screws. The Loctite Colour and Strength System Every Loctite threadlocker is colour-coded by strength. The colour tells you immediately whether the fastener can be released with standard hand tools or whether heat will be required for removal. Colour Strength Level Removability Common Grades Purple Low Hand tools — easily removable 222 Blue Medium Hand tools — standard spanners and sockets 242, 243 Red High / Permanent Heat required — 250°C before applying torque 262, 263, 271, 272, 277 Green Low to High (wicking grades) Depends on grade — see table below 270, 290 Loctite Threadlocker Grade Comparison Chart Grade Colour Strength Bolt Size Max Temp Removable? Primary Application 222 Purple Low M1.4–M6 150°C Yes — hand tools Small screws, grub screws, instrument hardware, adjustment fasteners 242 Blue Medium M6–M20 150°C Yes — hand tools General purpose — older formulation; performs identically to 243 on clean threads 243 Blue Medium M6–M20 150°C Yes — hand tools General purpose standard — improved oil tolerance over 242; preferred current-generation grade 262 Red High M6–M20 150°C Heat required (250°C) Studs, press-fit bolts, high-vibration assemblies — smaller fasteners than 263 263 Red High M6–M36 150°C Heat required (250°C) Large permanent fasteners — higher breakaway torque than 262; structural joints 270 Green High M6–M36 150°C Heat required Wicking grade — penetrates pre-assembled joints; post-assembly application 271 Red High M6–M36 150°C Heat required (250°C) High-strength general purpose — wheel bolts, studs, structural and safety-critical fasteners 272 Red High M6–M36 230°C Heat required High-temperature applications — exhaust manifold studs, engine components, hot environments 277 Red Very High M20–M36+ 150°C Heat required Very large fasteners — maximum breakaway torque for flanges, heavy plant, large structural bolts 290 Green Medium M6–M20 150°C Yes — hand tools Wicking grade — post-assembly on pre-assembled or production-line fasteners; medium strength Loctite 242 vs 243 — What Changed? Loctite 243 is the current-generation replacement for 242. Both are medium-strength blue threadlockers for M6–M20 fasteners, and both develop the same cured strength on clean, degreased steel. The key improvement in 243 is better tolerance to light oil contamination on threads. In a workshop environment where threads are occasionally oily, 243 cures reliably where 242 may underperform. If you have 242 on the shelf, use it — it is equivalent to 243 on clean surfaces. For new stock, specify 243. Loctite 243 vs 263 — The Most Important Distinction This is the most common and consequential selection decision. The choice is simple: will this fastener ever need to be removed? Use 243 (blue) when the fastener may need to be removed for service, adjustment or replacement. Under vibration, 243 provides equivalent security to red — it will not self-loosen. But a standard spanner or socket applied with normal force will break the bond. This is the correct grade for brake caliper bolts, suspension components, machinery access panels, and any fastener in the service path. Use 263 or 271 (red) when the assembly is permanent — a structural joint, a stud that will never be pulled, or a high-vibration application where even low probability of movement is unacceptable. These grades require heating to 250°C before the fastener can be turned. Using red on a service fastener, or on a small bolt where that heat cannot be applied safely, is the most common Loctite misapplication on the workshop floor. Threadlocker Application Selection Guide Application Recommended Grade Reason Small adjustment screws, grub screws, M1.4–M6 222 (Purple) Low strength only — blue or red on small threads risks stripping or irreversible locking General fasteners requiring future service access, M6–M20 243 (Blue) Medium strength, hand-tool removable, the standard industrial choice Brake caliper bolts 243 (Blue) Service access required; OEM specification for most passenger and light commercial vehicles Wheel spacer bolts 243 (Blue) Vibration resistance with removability for tyre changes and wheel service Bicycle and bike component bolts 222 (Purple) Critical — titanium and aluminium threads cannot handle medium or high strength; purple only Flywheel bolts, ring gear bolts 263 or 271 (Red) Permanent structural joint; high vibration; rarely or never removed in service life Exhaust manifold studs, turbo bolts 272 (Red) High-strength with 230°C continuous service temperature — the only threadlocker rated for exhaust temperatures Pre-assembled joints — wicking application 290 (Green, medium) or 270 (Green, high) Low viscosity penetrates assembled threads via capillary action — apply externally after assembly Large structural fasteners M20 and above 277 (Red) Maximum breakaway torque for large thread engagement in heavy plant and structural applications Stainless steel fasteners into stainless 243 + Loctite 7649 Activator N Passive metal — requires activator for reliable cure; see surface preparation section below Stainless Steel, Aluminium and Other Passive Metals Loctite anaerobic products cure by reacting with the metal ions present in the substrate. Passive metals — stainless steel, aluminium, titanium, zinc plating, cadmium plating — have an oxide layer that slows or prevents this reaction. On stainless-to-stainless assemblies without treatment, cure may be incomplete, slow (days rather than hours), or fail entirely in cold conditions. The solution is Loctite 7649 Activator N: apply a thin coat to one mating surface, allow 30–60 seconds to dry, then apply the Loctite threadlocker to the other surface and assemble normally. The activator overcomes the passive layer and initiates rapid, complete cure. This step is not optional on stainless — it is the difference between a joint that works and one that fails at the worst moment. Loctite Thread Sealants: Pipe, Hydraulic and Gas Applications Thread sealants seal tapered and parallel pipe threads against leakage of fluids and gases under pressure. They are a distinct product family from threadlockers — they are formulated for sealing pipe thread profiles (BSP, NPT, metric parallel), not for retaining standard bolts and fasteners. Product Type Max Pressure Max Temp Potable Water Best For Loctite 55 Sealing cord (PTFE alternative) 80 bar (gas) / 100 bar (liquid) −50°C to +130°C Yes — NSF 61 certified Gas, water, hydraulic; plastic and metal threads; instant pressure resistance on assembly Loctite 542 Anaerobic liquid 350 bar −65°C to +150°C No Fine metal hydraulic threads — instrumentation fittings, precision pneumatic connections Loctite 567 Anaerobic liquid 690 bar −65°C to +150°C No Metal pipe threads — hydraulic, pneumatic, fuel and oil systems; fine thread forms Loctite 577 Anaerobic liquid 400 bar −55°C to +150°C No Coarser BSP and NPT metal pipe threads — compressed air, water, oil and gas plumbing Loctite 55 — The PTFE Thread Seal Alternative Loctite 55 is not an anaerobic liquid — it is a continuous-filament sealing cord wound around threads by hand, replacing PTFE tape. Wound clockwise around the male thread (three to five turns for most fittings), it creates an immediate, compliant seal that develops full holding strength as the fitting is tightened. Its key advantages over PTFE tape: it can be hand-tightened to immediate pressure resistance with no cure wait; it works reliably on both metal and plastic fittings; it does not shred or delaminate into pipework; and it can be repositioned slightly after assembly if alignment is needed. Most importantly for Australian trade and construction applications, Loctite 55 is NSF 61 certified for potable water — it is the correct Loctite product for drinking water connections. It is also approved for gas service and is used on residential and commercial gas fittings where threaded connections are required. Loctite 567 vs 577 — Which Anaerobic Thread Sealant? Both 567 and 577 are anaerobic liquids that seal metal pipe threads. The difference is viscosity and thread form. Loctite 567 is lower viscosity — it wicks easily into fine hydraulic and pneumatic thread forms (SAE, metric fine), making it the correct choice for instrument fittings, hydraulic block connections and precision pneumatic assemblies where thread tolerances are tight. Loctite 577 is higher viscosity — it stays in place on coarser BSP and NPT threads during assembly, making it the standard choice for compressed air systems, water fittings and general industrial plumbing. If in doubt on a BSP fitting, use 577. If connecting hydraulic instrument tubing or fine metric threads, use 567. For cure times, fluid compatibility, passive metal guidance and a full application guide, see our Loctite 577 Thread Sealant Guide. Loctite Retaining Compounds: Bearing and Cylindrical Assembly Retaining compounds bond cylindrical assemblies — shaft-to-bearing, shaft-to-hub, pin-to-bore — by filling the microscopic clearance between components and polymerising into a rigid, load-bearing joint. They are used to augment or replace interference fits, to prevent fretting corrosion in light-clearance assemblies, and to salvage worn bores where a bearing has become loose in its housing. The two critical selection variables are the radial clearance between the mating components and the strength required. Using a product with a maximum clearance smaller than the actual gap will result in incomplete fill and significantly reduced bond strength. Grade Strength Max Clearance Max Temp Re-assemble? Best For 609 Low 0.10 mm 150°C Yes — press or hand Light-duty retention, small close-tolerance assemblies requiring re-use 638 High 0.15 mm 150°C With press or puller Close-tolerance bearing retention — maximum strength where fit is tight 641 Medium 0.25 mm 150°C Yes — press or puller Standard bearing and bushing retention — strength with serviceability 648 Maximum 0.15 mm 175°C Effectively no Permanent high-temperature assemblies where disassembly is never required 660 High 0.50 mm 150°C With press or puller Worn bore salvage — fills large clearances in worn housings and shafts 680 High 0.35 mm 150°C With press or puller General-purpose medium-to-large clearance bearing retention Choosing Between 638, 641 and 648 For new bearings in a correctly toleranced housing, 641 is the default choice. Medium strength, 0.25 mm maximum clearance, and removable with a standard bearing puller or hydraulic press — this covers the vast majority of bearing retention applications in industrial and agricultural equipment. Use 638 when the fit is very close and maximum strength is required. In a tight housing where interference fit alone is nearly sufficient, 638 augments the fit to create an exceptionally strong, permanent joint. Note that 638 in a tight bore with a light press fit is very difficult to disassemble — treat it as semi-permanent. Use 648 only when the assembly will never be disassembled and operating temperatures exceed 150°C. Loctite 648 is the most thermally resistant retaining compound and produces the highest bond strength in the range — but the joint is effectively destroyed on any attempt at disassembly. Reserve it for permanent high-temperature applications such as motor shaft assemblies in hot environments. For worn bores where the bearing is loose in the housing (clearance beyond 0.25 mm), use 660. It fills gaps up to 0.5 mm, locks the bearing in the oversized bore, and restores the housing to service without machining. This is the most commonly used retaining compound in field service and overhaul environments where worn machinery is being returned to service. Browse AIMS Industrial's full Loctite retaining compound range including 638, 641, 648 and 660. Loctite Anti-Seize Anti-seize does the opposite of a threadlocker. Where threadlockers lock fasteners in place by filling the thread void, anti-seize prevents fasteners from seizing, galling and corroding in ways that make them impossible to remove. Never apply both to the same fastener. Loctite C5-A Copper Anti-Seize is the industrial standard — a copper-based paste rated to 980°C. Correct applications include stainless-on-stainless assemblies where galling is a risk (anti-seize is far more effective than threadlocker at preventing galling), exhaust bolts and manifold studs subject to repeated heat cycling, fasteners in corrosive environments such as marine, chemical plant and agricultural equipment, and any assembly where long-term disassembly is essential. Important torque note: Anti-seize reduces the friction coefficient of threads. If torquing to a manufacturer specification designed for dry or lightly oiled threads, the torque value must be reduced when anti-seize is applied — typically by 20 to 25%. Applying full dry-thread torque with anti-seize present will over-stress the fastener. Surface Preparation: The Critical Step Loctite anaerobics cure by reacting with metal ions in the substrate. Surface contamination — oil, grease, coolant, cutting fluid, rust preventative — inhibits this reaction and reduces cured strength. Inadequate surface preparation is the primary cause of Loctite application failures. Standard preparation for all Loctite anaerobic products: Degrease both mating surfaces with Loctite 7063 cleaning solvent or isopropyl alcohol. Apply solvent, agitate if necessary to remove oil film, and allow to evaporate fully — do not assemble onto wet surfaces. On threaded fasteners, apply solvent to the bore threads and the bolt shank and allow to dry before applying Loctite. For passive metals (stainless steel, aluminium, titanium, zinc, cadmium plating): Apply Loctite 7649 Activator N to one surface and allow 30–60 seconds to dry before applying the Loctite product to the other surface. This step is not optional — without activator on stainless steel, cure is unreliable, particularly at temperatures below 15°C. The activator is low-cost and eliminates a significant failure mode. Cure Time Reference Product Type Grade Handling Strength (steel, 22°C) Full Cure Low-strength threadlocker 222 10 minutes 24 hours Medium-strength threadlocker 242, 243 10 minutes 24 hours High-strength threadlocker 262, 263, 271 20 minutes 24 hours High-temp threadlocker 272 20 minutes 24 hours (full high-temp rating requires post-cure at 120°C for 30 min) Wicking threadlocker 270, 290 15 minutes 24 hours Standard retaining compound 638, 641 10–15 minutes (fixture) 24 hours High-temp retaining compound 648 15 minutes (fixture) 24 hours (post-cure at 120°C recommended for full performance) Thread sealant 567, 577 Immediate pressure resistance 24 hours full cure Cold temperature note: Below 10°C, all cure times extend significantly — allow 48 to 72 hours for full cure in cold conditions. Cure can be accelerated to near-full strength by warming the assembled joint to 80°C for 30 minutes. On passive metals without activator, add 50% to all cure time estimates. Removing Loctite Threadlocker The correct removal method for any Loctite threadlocker — blue or red — is heat. Apply a heat gun or torch to bring the joint to approximately 250°C, then apply torque to the fastener immediately while the joint is still hot. The cured Loctite softens above this temperature and releases. Do not heat the joint and then allow it to cool before attempting removal — the Loctite will re-harden and lock the fastener again. Blue (medium strength) threadlocker: Heat to 250°C is effective but not always required. Strong, steady hand-tool force will release most blue-locked joints without heat. If a blue-locked fastener resists standard hand tool force, apply heat before increasing effort — forcing a locked fastener with an extension bar risks breaking the bolt or stripping the thread rather than releasing the Loctite. Red (high strength) threadlocker: Heat is not optional. Do not attempt to remove a red-locked fastener with hand tools alone — the breakaway torque exceeds what hand tools can safely apply on most bolt sizes. Apply direct heat to the joint, apply torque immediately while hot, and repeat the heat-and-torque cycle if the fastener does not break free on the first attempt. Aluminium and composite components: Use a heat gun rather than a torch to avoid warping or heat-damaging the surrounding material. Apply heat gradually and test the fastener for movement frequently rather than applying maximum heat in one go. If heat risks damaging adjacent components, soak the joint overnight with a penetrating oil to assist, then apply minimum heat to break free. After removal: Clean old Loctite from threads with a wire brush and solvent before re-applying fresh product. Do not re-apply new Loctite over hardened residue — the cured material does not dissolve or re-activate. Loctite Instant Adhesives: 401, 406 and the Cyanoacrylate Range Loctite's cyanoacrylate (CA) range — commonly called instant adhesives or superglue — are chemically distinct from the anaerobic products above. They cure by reacting with surface moisture rather than requiring the absence of oxygen or metal ions, and they are not suitable for thread locking, pipe sealing or cylindrical retention. Loctite 401 is the standard-viscosity general-purpose CA adhesive. It bonds metal, rubber, rigid plastics and most hard materials in seconds. For most instant adhesive applications in a trade or industrial workshop, 401 is the correct starting choice. See our Loctite 401 complete guide for full substrate compatibility, cure times and storage information. Loctite 406 is formulated for difficult substrates — polyolefin plastics (polyethylene, polypropylene), rubbers and elastomers that standard CA adhesives cannot reliably bond. It contains a surface-insensitive primer agent that promotes adhesion on low-energy surfaces. For bonding rubber seals to metal housings, or joining PP and PE components, 406 is significantly more reliable than 401. Loctite 454 is a gel-form CA that stays in position on vertical surfaces and fills small gaps — the correct choice where a liquid adhesive would run before the joint is closed, or where mating surfaces are slightly rough or porous. Loctite 480 is a rubber-toughened CA for applications requiring a flexible, impact-resistant bond — rubber-to-rubber and rubber-to-metal joints where a rigid brittle bond would crack under flexing. Loctite Product Equivalents The most frequently searched Loctite equivalent products come from the Permatex range. The approximate equivalents for the main industrial grades are: Loctite Grade Permatex Equivalent Notes 222 — Purple, low strength Permatex 24010 Functionally equivalent; verify application torque values independently 243 — Blue, medium strength Permatex 24200 Direct equivalent for general-purpose medium-strength applications 271 / 263 — Red, high strength Permatex 27200 High-strength equivalent; verify temperature ratings for your specific application When substituting between brands, always confirm that the equivalent grade meets your specific temperature, gap clearance and torque requirements — equivalent strength does not guarantee identical performance in all conditions. Lock it. Seal it. Trust it. Related AIMS Selectors This selector pairs with AIMS's other fastener & adhesive guides: Loctite 222 Guide — purple low-strength threadlocker deep-dive. Loctite 243 Guide — medium-strength workshop default. Loctite 401 Guide — instant adhesive (cyanoacrylate). Loctite 577 Guide — medium-strength thread sealant. Thread Locking & Sealing Guide — anaerobic chemistry + application technique. Industrial Adhesive Types Guide — broader adhesives hub: epoxy, RTV, structural. How to Remove Stuck Bolts & Nuts — when Loctite has done its job too well. Metric Bolt Torque Chart — torque values per grade and size. Or browse the full Loctite range, threadlockers, retaining compounds, gasket sealants, thread sealants, activators, cleaners & primers. Next-day Australia-wide dispatch from our Milperra warehouse. Shop the full Loctite range — threadlockers, retaining compounds & sealants From Loctite 222 low-strength to 263 high-strength threadlocker, 641 retaining compound, and 55 pipe sealant — AIMS Industrial is an authorised Loctite stockist with the full range available for fast Australia-wide dispatch. Shop Loctite at AIMS Talk to a specialist Frequently Asked Questions What is the best Loctite threadlocker for small screws?Loctite 222 (purple) is the only correct choice for screws up to M6. Small threads — grub screws, electronics fasteners, instrument hardware, adjustment screws — do not have sufficient thread engagement to handle the breakaway torque of medium or high-strength threadlocker. Applying blue (243) to an M3 or M4 grub screw will very likely make it impossible to remove without damaging the threads or the housing. Use purple (222) for anything M6 and smaller, without exception. What is the difference between blue and red Loctite?Blue Loctite (243) is medium strength and removable with hand tools — the standard choice for fasteners that need to be serviced, adjusted or replaced in the future. It will not self-loosen under vibration, but a spanner or socket applied with normal force will release it. Red Loctite (263, 271) is high strength and permanently locks the fastener — it requires heating the joint to 250°C before any torque will release it. The correct rule: if the fastener may ever need to come off, use blue. If it is a truly permanent structural joint, use red. Which Loctite threadlocker is the strongest?In the standard threadlocker range, Loctite 277 (red) has the highest breakaway torque and is formulated for large-diameter fasteners (M20–M36+). For the M6–M36 range, Loctite 263 and 271 provide effectively equivalent maximum strength for most applications. Loctite 648 is the maximum-strength retaining compound for cylindrical assemblies, though it serves a different function. For most industrial work, 271 or 263 provide more than sufficient permanent locking strength. Can Loctite cure on oily or contaminated threads?Standard threadlocker grades (242, 263) require clean, degreased surfaces for full strength development. Loctite 243 is formulated with improved oil tolerance and will cure acceptably on lightly oiled threads. On heavily contaminated or wet surfaces, no anaerobic product will achieve full strength — clean first. For post-assembly applications where disassembly is not practical, a wicking grade (290 for medium strength, 270 for high strength) applied to the external thread after cleaning the exposed surface will penetrate and lock the joint, but ultimate strength depends on the cleanliness of the thread interface. Can Loctite threadlocker be used on plastic threads?Anaerobic threadlockers require metal ions to cure and are formulated for metal-to-metal contact. On plastic threads, cure is unreliable, strength is substantially reduced, and certain Loctite formulations can stress-crack specific plastics — notably polystyrene and polycarbonate. For sealing plastic pipe fittings, use Loctite 55 sealing cord — it works on plastic threads without chemical incompatibility risk. For retention on plastic fasteners, mechanical solutions (nylon insert nuts, serrated flange fasteners) are more reliable than chemical threadlockers. Are Loctite thread sealants suitable for potable water pipes?Loctite 55 sealing cord is NSF 61 certified for potable water and is the correct Loctite product for any fitting in contact with drinking water. The anaerobic liquid sealants — 567 and 577 — are not NSF 61 certified and must not be used on potable water connections. For gas pipe connections (residential and commercial), Loctite 55 is also approved and is used on threaded gas fittings in Australia. It replaces PTFE tape in these applications with no need for cure time before pressurisation. How long does Loctite threadlocker take to fully cure?On clean steel at 22°C, most grades reach handling strength in 10–20 minutes — sufficient to torque the fastener and move the assembly without disturbing the joint. Full cure takes 24 hours. Below 10°C, cure times extend significantly — allow 48 to 72 hours at low temperatures. Cure can be accelerated by heating the assembled joint to 80°C for 30 minutes. On passive metals (stainless steel, aluminium) without activator, add at least 50% to all cure times and treat handling strength with caution. How do I remove a bolt locked with red Loctite threadlocker?Heat the joint directly to approximately 250°C using a heat gun or butane torch, then apply torque to the fastener immediately while it is still hot. The cured Loctite softens at this temperature and allows the fastener to turn. Do not heat the joint and then allow it to cool before trying — the Loctite re-hardens on cooling. If the fastener does not release on the first attempt, re-apply heat and try again. Never use an impact wrench on a locked fastener without heating first — the risk of shearing the bolt is significantly higher than the effort of applying heat. What is the difference between Loctite 567 and 577 thread sealant?Both are anaerobic liquids for sealing metal pipe threads. Loctite 567 is lower viscosity — it wicks easily into fine thread forms (SAE hydraulic fittings, metric fine, instrument connections) and is the correct choice for hydraulic and pneumatic precision connections. Loctite 577 is higher viscosity and stays in position on coarser BSP and NPT pipe threads during assembly. For most compressed air, water and gas plumbing on BSP fittings, 577 is the standard choice. For hydraulic block connections and instrument fittings with fine thread forms, use 567. See our full Loctite 577 Thread Sealant Guide for the complete application reference. Which Loctite retaining compound should I use for bearing retention?For standard bearing retention with normal bore clearance, Loctite 641 is the default choice — medium strength, handles clearances up to 0.25 mm, and the bearing can be removed with a press or standard puller for service. Use Loctite 638 for close-tolerance fits requiring maximum bond strength. Use Loctite 660 for worn bores with clearance above 0.25 mm — it fills gaps up to 0.5 mm and locks a loose bearing in an oversized housing without machining. Reserve Loctite 648 for permanent high-temperature assemblies that will never be disassembled. What is the difference between Loctite 401 and 406?Loctite 401 is a standard-viscosity cyanoacrylate (instant adhesive) for general bonding of metal, rubber and most rigid plastics. Loctite 406 is formulated specifically for difficult low-energy substrates — polyolefin plastics (polyethylene, polypropylene) and elastomers that standard CA adhesives cannot reliably bond. If you're bonding rubber gaskets, polypropylene fittings or PE components, 406 is the correct grade. For metal-to-metal, glass-to-metal or general rigid bonding, 401 is sufficient. The 406 premium is only justified where the substrate is a known adhesive-resistant plastic or rubber. For metric bolt diameter, pitch and head dimensions from M3 to M24, see our Metric Bolt Size Guide. People Also Ask — Loctite Grade Selection Q: What is the difference between Loctite 243 and Loctite 263? Loctite 243 is a medium-strength threadlocker removable with hand tools after cure — suitable for most fasteners M6 to M20 where future disassembly is expected. Loctite 263 is high-strength and permanently bonds fasteners; removal requires heat above 250°C. Use 243 for routine maintenance, 263 where vibration risk is severe and disassembly is not planned. Q: How long does Loctite threadlocker take to cure? Loctite 243 achieves handling strength in approximately 10 minutes on steel at 22°C. Full chemical cure takes 24 hours. Cure is slower on passive metals (stainless steel, zinc) and in cold conditions — allow extra time before applying service loads. Activator SF 7649 speeds cure on passive metals. Q: Can you use Loctite on aluminium threads? Yes. Loctite anaerobic threadlockers including Loctite 222, 243, and 263 are compatible with aluminium. Aluminium is a passive metal, so cure is slower than on steel. Apply Loctite Activator SF 7649 to one thread surface first to achieve reliable cure speed and strength on aluminium fasteners. Q: What Loctite grade is best for stainless steel fasteners? Loctite 243 medium-strength or Loctite 263 high-strength both work on stainless steel, but stainless is a passive metal — always apply Activator SF 7649 first. For stainless fasteners in food or hygienic environments, Loctite 2400 is a water-washable, low-odour alternative approved for incidental food contact. Q: What is Loctite 577 used for? Loctite 577 is a medium-strength thread sealant for parallel (BSP) threads used in hydraulic and pneumatic systems. It seals metal-to-metal pipe threads and fitting connections against fluid and gas leakage up to 150 bar, while remaining removable with hand tools for maintenance. Not a threadlocker — designed specifically for fluid-system thread sealing. Looking for anti-vibration mounts? Our anti-vibration mounts range covers the common sizes and brands. Looking for anti-seize compounds? Our anti-seize compounds range covers the common sizes and brands.
Read more
Pulley Speed Ratio Calculator & Formula Explained
Pulley Speed Ratio Formula The pulley speed ratio is the relationship between drive and driven pulley diameters that determines how fast the driven pulley turns. The formula: V2 = V1 × (D1 ÷ D2) Worked example: a 100mm drive pulley spinning at 1,800 RPM connected by belt to a 200mm driven pulley. V2 = 1,800 × (100 ÷ 200) = 900 RPM. The driven pulley turns at half the speed but produces roughly double the torque. Rule of thumb: a smaller driven pulley (relative to the drive) spins faster with less torque; a larger driven pulley spins slower with more torque. To increase driven speed, fit a smaller driven pulley or a larger drive pulley. The formula can also solve for required pulley size: D2 = D1 × (V1 / V2). Common questions answered by this formula: what happens if I change pulley size; does a bigger drive pulley increase speed; how do I slow down a driven shaft. People Also Ask — Pulley Speed Ratio Calculator & Formula Explained Q: How do I calculate pulley speed ratio? Speed ratio = Driver diameter ÷ Driven diameter. If the driving pulley is 100 mm and the driven pulley is 200 mm, the ratio is 0.5:1 — the driven shaft runs at half the motor speed. To find driven shaft speed: V2 = V1 × (D1 ÷ D2), where V1 is motor RPM and D1/D2 are the pulley diameters. Q: How do I increase torque using pulleys? Use a larger driven pulley relative to the driver — the driven shaft slows down but torque increases proportionally (ignoring belt slip and friction losses). For example, a 2:1 ratio (driver 100 mm, driven 200 mm) doubles the torque at the output shaft. This is the standard approach for conveyor drives, fans, and compressors requiring high torque at lower speed. Q: What happens if my pulleys are misaligned? Belt misalignment causes uneven wear on one edge of the belt, premature sidewall cracking, and increased bearing load. Symptoms include belt squealing under load, rapid belt failure, and visible tracking to one side. Check alignment with a straight edge across both pulley faces — grooves must be co-planar within approximately 1 mm per 300 mm of centre distance. Q: How do I choose the right pulley size for my motor? Start with the required output speed, then work backwards: D1 = D2 × (V2 ÷ V1). Account for belt slip (1–2% for V-belts). Also check that the pulley diameter is within the minimum recommended for your belt section — using undersized pulleys causes excessive bending stress, generating heat and shortening belt life significantly.
Read more
Metric vs Imperial: How to Choose the Right Fastener for the Job | AIMS Industrial
The closest imperial equivalent to M8 is 5/16", M10 is 3/8", and M12 is 1/2". Metric (M-series) and imperial (UNC/UNF/BSW/BSF) threads share only nominal diameter — pitch and TPI differ, so they are not interchangeable. The compact reference below covers the most-used conversions; the full chart with thread pitch, TPI, BA and large sizes follows. Quick answer — metric to imperial M3 ≈ 4-40 / #5 · M4 ≈ 8-32 / #8 · M5 ≈ #10 / 10-32 · M6 ≈ 1/4" · M8 ≈ 5/16" · M10 ≈ 3/8" · M12 ≈ 1/2" · M14 ≈ 9/16" · M16 ≈ 5/8" · M20 ≈ 3/4" · M22 ≈ 7/8" · M24 ≈ 15/16" · M27 ≈ 1-1/16" · M30 ≈ 1-3/16" ⚠️ Diameter only. Thread pitch / TPI differs — metric and imperial fasteners are not interchangeable. Full pitch and TPI chart below. Need another reference chart? Browse the full AIMS Engineering Reference Charts library — drill bit sizes, tap drill, torque, viscosity, GD&T, AS/NZS standards and more. Metric to Imperial Fastener Quick Reference The most common metric fastener sizes and their closest imperial equivalents: Metric UNC / UNF (US) BSW / BSF (UK) M3 1/8" 1/8" M5 3/16" 3/16" M6 1/4" 1/4" M8 5/16" 5/16" M10 3/8" 3/8" M12 1/2" 1/2" M14 9/16" 9/16" M16 5/8" 5/8" M20 3/4" 3/4" M24 1" 1" Thread Pitch vs. Threads Per Inch Metric and imperial fasteners use different systems to describe thread spacing, and understanding the difference is essential before cross-referencing sizes. Metric fasteners use thread pitch. Thread pitch is the distance in millimetres between adjacent threads. A lower pitch number means finer threads. Metric fasteners are identified by the prefix M followed by the nominal diameter — for example, M8. Coarse thread (standard) has a larger pitch; fine thread has a smaller pitch. American fasteners use threads per inch (TPI). TPI counts how many threads fit in one inch. A higher TPI means finer threads. The Unified Thread Standard covers two main series: Unified National Coarse (UNC) for general use, and Unified National Fine (UNF) for applications requiring higher tensile strength or finer adjustment. British fasteners use threads per inch too. British Standard Whitworth (BSW) is the coarse series and British Standard Fine (BSF) is the fine series — both expressed in TPI using fractional inch nominal sizes. British Association (BA) threads are a smaller-diameter series, identified by a number suffix (0BA being the largest) with their own TPI values. Metric to Imperial Fastener Conversion Chart Refer to this table when cross-referencing your bolt, nut or screw. Not all metric fasteners have imperial equivalents and vice versa. Metric (Pitch in mm) Unified Thread Standard (Threads Per Inch) British Standard (Threads Per Inch) BA Size Coarse (mm) Fine (mm) Size Coarse (UNC) Fine (UNF) Size Coarse (BSW) Fine (BSF) -- -- -- -- #0000 -- 160 -- -- -- -- -- -- -- -- #000 -- 120 -- -- -- -- -- -- -- -- #00 -- 90 -- -- -- -- M1.6 0.35 0.20 -- #0 -- 80 -- -- -- -- M2 0.40 0.25 -- #1 64 72 -- -- -- -- -- -- -- -- -- -- -- 1/16" 60 -- -- -- -- -- -- #2 56 64 8BA -- -- 59.1 M2.5 0.45 0.35 -- #3 48 56 -- -- -- -- -- -- -- -- -- -- -- 3/32" 48 -- -- -- -- -- -- #4 40 48 6BA -- -- 47.9 M3 0.50 0.35 1/8" #5 40 44 1/8" 40 -- -- M3.5 0.60 0.35 -- #6 32 40 4BA -- -- 38.5 -- -- -- -- -- -- -- 5BA -- -- 43 M4 0.70 0.50 -- #8 32 36 3BA -- -- 34.8 M4.5 0.75 0.50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2BA -- -- 31.4 M5 0.80 0.50 3/16" #10 24 32 3/16" 24 32 32 M5.5 -- 0.50 -- -- -- -- -- -- -- -- -- -- -- -- #12 24 28 1BA -- -- 28.2 M6 1.00 0.75 -- -- -- -- 0BA -- -- 25.4 -- -- -- 1/4" -- 20 28 1/4" 20 26 -- M7 1.00 0.75 -- -- -- -- 9/32" -- 26 -- M8 1.25 1.00 5/16" -- 18 24 5/16" 18 22 -- M9 1.25 1.00 -- -- -- -- -- -- -- -- M10 1.50 1.25 3/8" -- 16 24 3/8" 16 20 -- M11 1.50 1.00 -- -- -- -- -- -- -- -- -- -- -- 7/16" -- 14 20 7/16" 14 18 -- M12 1.75 1.25 1/2" -- 13 20 1/2" 12 16 -- M14 2.00 1.50 9/16" -- 12 18 9/16" 12 16 -- M15 -- 1.50 -- -- -- -- -- -- -- -- M16 2.00 1.50 5/8" -- 11 18 5/8" 11 14 -- M17 -- 1.50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 11/16" 11 14 -- M18 2.50 1.50 -- -- -- -- -- -- -- -- M20 -- 1.50 3/4" -- 10 16 3/4" 10 12 -- M22 2.50 1.50 7/8" -- 9 14 7/8" 9 11 -- M24 3.00 2.00 1" -- 8 14 / 12 1" 8 10 -- M25 -- 2.00 -- -- -- -- -- -- -- -- M27 -- 2.00 1 1/8" -- 7 12 1 1/8" 7 9 -- M28 -- 2.00 -- -- -- -- -- -- -- -- M30 3.50 2.00 1 1/4" -- 7 12 1 1/4" 7 9 -- M32 -- 2.00 -- -- -- -- -- -- -- -- M33 3.50 2.00 1 3/8" -- 6 12 1 3/8" 6 / 7 8 -- M35 -- 1.50 -- -- -- -- -- -- -- -- M36 4.00 3.00 1 1/2" -- 6 12 1 1/2" 6 8 -- M38 -- 1.50 -- -- -- -- -- -- -- -- M39 4.00 3.00 1 5/8" -- -- -- 1 5/8" 5 8 -- M40 -- 3.00 -- -- -- -- -- -- -- -- M42 4.50 4.00 -- -- -- -- -- -- -- -- M45 4.50 4.00 1 3/4" -- 5 -- 1 3/4" 5 7 -- M48 5.00 4.00 1 7/8" -- 5 -- -- -- -- -- M50 -- 3.00 -- -- -- -- -- -- -- -- M52 5.00 4.00 2" -- 4.5 -- 2" 4.5 7 -- M55 -- 4.00 -- -- -- -- -- -- -- -- M56 5.50 4.00 2 1/4" -- 4.5 -- 2 1/4" 4 6 -- M58 -- 4.00 -- -- -- -- -- -- -- -- M60 5.50 4.00 -- -- -- -- -- -- -- -- M62 -- 4.00 -- -- -- -- -- -- -- -- M64 6.00 4.00 2 1/2" -- 4 -- 2 1/2" 4 6 -- M65 -- 4.00 -- -- -- -- -- -- -- -- M68 6.00 4.00 -- -- -- -- -- -- -- -- M70 6.00 4.00 -- -- -- -- -- -- -- -- M72 6.00 4.00 2 3/4" -- 4 -- 2 3/4" 3.5 6 -- M75 -- 4.00 -- -- -- -- -- -- -- -- M76 6.00 4.00 -- -- -- -- -- -- -- -- M78 -- 2.00 -- -- -- -- -- -- -- -- M80 6.00 4.00 3" -- 4 -- 3" 3.5 5 -- -- -- -- 3 1/4" -- 4 -- 3 1/4" 3.25 5 -- M85 6.00 4.00 -- -- -- -- -- -- -- -- M90 6.00 4.00 3 1/2" -- 4 -- 3 1/2" 3.25 4.5 -- -- -- -- 3 3/4" -- 4 -- 3 3/4" 3 4.5 -- M100 6.00 -- 4" -- 4 -- 4" 3 4.5 -- -- -- -- -- -- -- -- 4 1/4" 2.875 4 -- -- -- -- -- -- -- -- 4 1/2" 2.875 -- -- -- -- -- -- -- -- -- 4 3/4" 2.75 -- -- -- -- -- -- -- -- -- 5" 2.75 -- -- -- -- -- -- -- -- -- 5 1/4" 2.625 -- -- -- -- -- -- -- -- -- 5 1/2" 2.625 -- -- -- -- -- -- -- -- -- 5 3/4" 2.5 -- -- -- -- -- -- -- -- -- 6" 2.5 -- -- What Else to Consider When Selecting Fasteners Aside from thread pitch or TPI, the following factors affect whether a fastener is right for your application: the fastener type (bolt, nut, screw or stud); head style; strength grade or property class; material and surface finish (zinc, stainless, hot-dip galvanised); tensile rating; and thread engagement length. Where possible, have a sample fastener on hand to verify diameter, pitch and thread form before ordering. Related Size Charts Drill Bit Size Chart — metric, imperial and gauge drill bit sizes matched in a single reference table. Socket Size Chart — metric and imperial socket sizes with drive equivalents. Spanner Size Chart — spanner sizes matched to bolt and nut hex sizes across metric and imperial. Tapping Drill Size Chart — drill sizes for cutting metric and imperial threads with hand taps. Metric vs Imperial Fasteners Guide — which thread system is standard in Australia, how UNC, UNF, BSW and BSF compare to metric, and when the two are (and aren't) interchangeable. Frequently Asked Questions What is M3 in imperial? M3 has the closest imperial equivalent of 4-40 UNC or #5 gauge. M3 is 3mm nominal diameter with 0.5mm coarse pitch. The exact match is 0.118 inches — there is no exact imperial bolt at this size, so #5 is the closest standard. What is M4 in imperial? M4 has the closest imperial equivalent of 8-32 UNC or #8 gauge. M4 is 4mm nominal diameter with 0.7mm coarse pitch (1/8 inch is close but not identical at 0.157"). They are not interchangeable — thread pitch differs. What is M5 in imperial? M5 has the closest imperial equivalent of #10 (10-24 UNC or 10-32 UNF). M5 is 5mm nominal diameter with 0.8mm coarse pitch. The match is approximate — diameter is close but thread pitches do not match. What is M6 in imperial? M6 has the closest imperial equivalent of 1/4 inch. M6 is 6mm diameter with 1.0mm coarse pitch; 1/4" UNC is 20 TPI (1.27mm pitch) and 1/4" UNF is 28 TPI (0.91mm pitch). They are close in diameter only — not interchangeable. What is M8 in imperial? M8 has the closest imperial equivalent of 5/16 inch (UNC: 18 TPI, UNF: 24 TPI). M8 is 8mm diameter with 1.25mm coarse pitch and 1.0mm fine pitch. The diameter is close (5/16" = 7.94mm) but threads do not match. What is M10 in imperial? M10 has the closest imperial equivalent of 3/8 inch. M10 is 10mm diameter with 1.5mm coarse pitch; 3/8" UNC is 16 TPI (1.59mm pitch) and 3/8" UNF is 24 TPI (1.06mm pitch). M10 = 10mm, 3/8" = 9.525mm — close but not identical. What is M12 in imperial? M12 has the closest imperial equivalent of 1/2 inch. M12 is 12mm diameter with 1.75mm coarse pitch; 1/2" UNC is 13 TPI (1.95mm pitch) and 1/2" UNF is 20 TPI (1.27mm pitch). M12 = 12mm, 1/2" = 12.7mm. What is M14 in imperial? M14 has the closest imperial equivalent of 9/16 inch (14.29mm). M14 is 14mm diameter with 2.0mm coarse pitch; 9/16" UNC is 12 TPI (2.12mm pitch). Diameter is close, pitch differs. What is M16 in imperial? M16 has the closest imperial equivalent of 5/8 inch (15.88mm). M16 is 16mm diameter with 2.0mm coarse pitch; 5/8" UNC is 11 TPI (2.31mm pitch) and 5/8" UNF is 18 TPI (1.41mm pitch). What is M20 in imperial? M20 has the closest imperial equivalent of 3/4 inch (19.05mm). M20 is 20mm diameter with 2.5mm coarse pitch; 3/4" UNC is 10 TPI (2.54mm pitch). What is M30 in imperial? M30 has the closest imperial equivalent of 1-3/16 inch (30.16mm). M30 is 30mm diameter with 3.5mm coarse pitch. How do I convert metric bolt sizes to imperial? Use the conversion table above to cross-reference your metric size (M-series) with the nearest UTS (UNC/UNF) or British Standard (BSW/BSF) equivalent. Note that metric and imperial threads are not interchangeable — only the nominal diameter is comparable. Always verify thread pitch or TPI before substituting fasteners. What is the difference between UNC and UNF threads? UNC (Unified National Coarse) threads have fewer threads per inch and are used in general construction and engineering. UNF (Unified National Fine) threads have more threads per inch, providing finer thread form for greater tensile strength or finer adjustability. Example: 1/4" UNC is 20 TPI while 1/4" UNF is 28 TPI. Is M10 the same as 3/8 inch? M10 and 3/8" are close in diameter (M10 = 10mm, 3/8" = 9.525mm) but they are not interchangeable. M10 coarse is 1.50mm pitch, while 3/8" UNC is 16 TPI (1.588mm pitch) and 3/8" UNF is 24 TPI. Always match both diameter and thread pitch when selecting a fastener. What does the M in metric fastener sizes mean? The M stands for metric, and the number that follows is the nominal outer diameter in millimetres. So M8 has a nominal diameter of 8mm, M10 is 10mm, and so on. Metric fasteners also specify thread pitch in millimetres — for example, M8 x 1.25 means 8mm diameter with a 1.25mm thread pitch. Are metric and imperial fasteners interchangeable? No. Even when the diameter looks close (M8 vs 5/16", M10 vs 3/8", M12 vs 1/2"), the thread pitch differs and forcing a metric bolt into an imperial thread (or vice versa) will strip or cross-thread it. Use the correct standard for the receiving thread — always. Ready to order? Shop our full range of metric & imperial fasteners From hex bolts to self-tapping screws — AIMS Industrial stocks thousands of fasteners across both standards, ready to ship Australia-wide. Browse fasteners Talk to a specialist Pair this with our Thread Standards Guide for the parallel-vs-tapered distinction and AS 1722 standards. People Also Ask — Metric vs Imperial: How to Choose the Right Fastener for the Job Q: What does M8 mean on a bolt? M8 denotes a metric bolt with an 8 mm nominal thread diameter. The 'M' stands for metric ISO thread form. An M8 bolt typically uses a 13 mm spanner across the hex head for coarse-pitch (1.25 mm pitch) versions — the most common standard for general fastening. Q: How do I identify a bolt grade from its head markings? Metric bolts show grade markings as numbers on the head — 8.8 means tensile strength of 800 MPa with yield at 80% of that, while 10.9 and 12.9 are higher grades. Imperial grades use radial lines: 3 lines = SAE Grade 5, 6 lines = SAE Grade 8. Unmarked bolts are generally Grade 4.6 or lower. Q: What is the difference between UNC and UNF threads? UNC (Unified National Coarse) has fewer, larger threads per inch — stronger in soft materials and faster to assemble. UNF (Unified National Fine) has more threads per inch, giving better resistance to vibration loosening and finer adjustment. UNC is the default choice for most structural fastening; UNF suits precision applications. Q: How do I choose between metric and imperial fasteners for Australian equipment? Most modern Australian industrial equipment is metric, per AS/NZS standards. Imperial fasteners (BSW, BSF, UNC, UNF) are common in older machinery, American equipment, and agriculture. When mixing is unavoidable, use thread gauges to verify — mismatched threads can appear to engage but will fail under load. Need metric thread forming taps? Browse the AIMS range at metric thread forming taps. For metric spiral point taps, see our metric spiral point taps range stocked across Australia.
Read more
Tap Drill Size Chart: Metric & Imperial Thread Sizes
Tap drill size is the diameter of the pilot hole drilled before threading. The rule: drill diameter = thread outer diameter − thread pitch. For M8 × 1.25 coarse, the tap drill is 6.8mm. For 1/4" BSP, it's 11.8mm. The compact reference below covers the most-used metric coarse sizes; full metric fine, BSP, UNC and UNF charts are further down. (If you are looking for the Sutton Tap & Drill Chart PDF, click here.) Quick answer — most common sizes Metric coarse: M3 = 2.5mm · M4 = 3.3mm · M5 = 4.2mm · M6 = 5.0mm · M8 = 6.8mm · M10 = 8.5mm · M12 = 10.2mm · M14 = 12.0mm · M16 = 14.0mm · M20 = 17.5mm BSP: 1/8" = 8.8mm · 1/4" = 11.8mm · 3/8" = 15.0mm · 1/2" = 18.6mm UNC: 1/4"-20 = 5.1mm · 5/16"-18 = 6.9mm · 3/8"-16 = 7.9mm · 1/2"-13 = 10.7mm Formula: tap drill (mm) = thread OD − pitch. Full charts below. For more engineering reference charts and selection tables, see our Engineering Reference Charts hub — covering fasteners, bearings, lubrication, measuring, welding and Australian standards. Tap & Drill Bit Selector — Most-Asked Metric Sizes This page is a working selector tool — not just a reference. Use it to get the right tap and drill into your hand in one click. The 10 most-asked metric thread sizes at AIMS are below. For less common sizes, scroll to the full charts further down (use the jump-nav below). How to use: 1. Find your thread size 2. See the matching tap drill diameter 3. Click Buy Tap or Buy Drill — sized to match M3 Tap drill 2.5 mm Buy tap → Buy drill → M4 Tap drill 3.3 mm Buy tap → Buy drill → M5 Tap drill 4.2 mm Buy tap → Buy drill → M6 Tap drill 5.0 mm Buy tap → Buy drill → M8 Tap drill 6.8 mm Buy tap → Buy drill → M10 Tap drill 8.5 mm Buy tap → Buy drill → M12 Tap drill 10.2 mm Buy tap → Buy drill → M14 Tap drill 12.0 mm Buy tap → Buy drill → M16 Tap drill 14.0 mm Buy tap → Buy drill → M20 Tap drill 17.5 mm Buy tap → Buy drill → Default recommendation: Sutton Spiral Point HSS taps and Sutton D101 Silver Bullet HSS jobber drills — the workshop standard for mild steel. AIMS also stocks Bordo and P&N as alternates. For stainless steel or hardened steel, switch to cobalt drill bits + cobalt taps (see the "By Material" section below). Need help? Call us on (02) 9773 0122. Jump to: Metric Coarse Metric Fine BSP UNC UNF By Material Related Selectors Tap Drill Size Chart — Metric Coarse Quick Reference The most frequently used metric coarse thread sizes and their tap drill diameters: Thread Tap Drill (mm) Thread Tap Drill (mm) M3 2.5 M12 10.2 M4 3.3 M14 12.0 M5 4.2 M16 14.0 M6 5.0 M18 15.5 M8 6.8 M20 17.5 M10 8.5 M24 21.0 How to Use This Chart Tap drill size refers to the diameter of the hole you drill before running a tap through it. The hole must be smaller than the thread's outer diameter, leaving enough material for the tap to cut the thread profile. Too large and the thread is shallow and weak. Too small and you risk breaking the tap. As a general rule, tap drill size = thread outer diameter − thread pitch. This gives approximately 75% thread engagement, which is standard for most applications. For softer materials or where tap breakage is a concern, go slightly larger. For maximum thread strength in hard materials, go slightly smaller. By accurately matching the tap size to the drill size and choosing the right tap for the job, you can achieve optimal results in your thread cutting operations. Metric Coarse Tap Drill Size Chart Metric coarse is the standard thread series for most bolts, screws and tapped holes in general engineering. Pitch is expressed in millimetres — a lower number means finer threads. These are the sizes you'll use for the vast majority of metric tapping work. Need help finding your size? Call AIMS on (02) 9773 0122 — the team can confirm stock and pick the right tap type for your job. Or browse all metric coarse taps and jobber drill bits. Thread Size Pitch (mm) Tap Drill (mm) Tap Drill (inch approx.) M1 0.25 0.75 --- M1.2 0.25 0.95 --- M1.4 0.30 1.10 --- M1.6 0.35 1.25 --- M1.8 0.35 1.45 --- M2 0.40 1.60 1/16" M2.5 0.45 2.05 5/64" M3 0.50 2.50 3/32" M3.5 0.60 2.90 7/64" M4 0.70 3.30 1/8" M5 0.80 4.20 11/64" M6 1.00 5.00 13/64" M7 1.00 6.00 15/64" M8 1.25 6.80 17/64" M10 1.50 8.50 21/64" M12 1.75 10.20 25/64" M14 2.00 12.00 15/32" M16 2.00 14.00 35/64" M18 2.50 15.50 39/64" M20 2.50 17.50 11/16" M22 2.50 19.50 49/64" M24 3.00 21.00 53/64" M27 3.00 24.00 15/16" M30 3.50 26.50 1-3/64" M33 3.50 29.50 1-5/32" M36 4.00 32.00 1-17/64" M39 4.00 35.00 1-3/8" M42 4.50 37.50 1-15/32" M45 4.50 40.50 1-19/32" M48 5.00 43.00 1-11/16" Metric Fine Tap Drill Size Chart Metric fine threads are used where vibration resistance, fine adjustment, or higher tensile strength is required — common in automotive, aerospace, and precision engineering applications. Multiple pitches exist per diameter; confirm your pitch before selecting the drill. Need help finding your size? Call AIMS on (02) 9773 0122 — the team can confirm stock and pick the right tap type for your job. Or browse all metric fine taps and jobber drill bits. Thread Size Pitch (mm) Tap Drill (mm) M1 × 0.2 0.20 0.80 M1.2 × 0.2 0.20 1.00 M1.4 × 0.2 0.20 1.20 M1.6 × 0.2 0.20 1.40 M2 × 0.25 0.25 1.75 M2.5 × 0.35 0.35 2.15 M3 × 0.35 0.35 2.65 M3.5 × 0.35 0.35 3.15 M4 × 0.5 0.50 3.50 M5 × 0.5 0.50 4.50 M6 × 0.75 0.75 5.25 M7 × 0.75 0.75 6.25 M8 × 0.75 0.75 7.25 M8 × 1.0 1.00 7.00 M10 × 0.75 0.75 9.25 M10 × 1.0 1.00 9.00 M10 × 1.25 1.25 8.75 M12 × 1.0 1.00 11.00 M12 × 1.25 1.25 10.75 M12 × 1.5 1.50 10.50 M14 × 1.0 1.00 13.00 M14 × 1.25 1.25 12.75 M14 × 1.5 1.50 12.50 M16 × 1.0 1.00 15.00 M16 × 1.5 1.50 14.50 M18 × 1.5 1.50 16.50 M18 × 2.0 2.00 16.00 M20 × 1.5 1.50 18.50 M20 × 2.0 2.00 18.00 M22 × 1.5 1.50 20.50 M22 × 2.0 2.00 20.00 M24 × 1.5 1.50 22.50 M24 × 2.0 2.00 22.00 M27 × 2.0 2.00 25.00 M30 × 1.5 1.50 28.50 M30 × 2.0 2.00 28.00 M33 × 2.0 2.00 31.00 M36 × 1.5 1.50 34.50 M36 × 3.0 3.00 33.00 Tap & Drill Selection by Material The right tap drill diameter is one half of the job. The other half is choosing tap and drill geometry that match your workpiece material. This is where most beginner tappers come unstuck — wrong tap type for the material means broken taps, oversized threads, or torn surface finishes. Here's what the AIMS workshop crew reaches for, by material: Mild steel (most common workshop material) Drill: Sutton D101 Silver Bullet HSS jobber (bright finish, 118° point) for occasional tapping. Sutton D102 Blue Bullet HSS (steam-oxide finish) for production tapping — the steam oxide finish helps swarf release on steel. Tap: Sutton Spiral Point HSS taps (T1xx series) for through holes — fastest, swarf pushes ahead of the tap. For blind holes, switch to Spiral Flute (T2xx series) so swarf evacuates upward and out of the hole. Lubricant: Tap Magic Original or any general-purpose cutting fluid. Stainless steel (304, 316, 17-4 PH) Drill: Cobalt drill bit — Sutton D108 or D109 cobalt jobber. The 5% to 8% cobalt content lets the drill stay sharp through stainless's work-hardening tendency. HSS bright drills will glaze the hole surface, work-harden the steel, and snap on the next pass. Tap: Cobalt steel tap — Sutton Spiral Flute Premium HSS Cobalt or Sutton Premium HSS Tinite-coated. The cobalt grade survives the harder material; cheap HSS chrome taps will snap on the first thread. Lubricant: Tap Magic for Stainless Steel — specifically formulated. Don't skimp here. Aluminium, brass, copper, plastics Drill: Standard HSS Sutton D101 Silver Bullet is fine. Some users prefer a slightly higher helix angle drill for softer non-ferrous materials — Sutton's 130° or 140° point geometry options. Tap: Spiral Flute tap is excellent here — long stringy chips need to evacuate cleanly, and spiral flute pulls them up and out. Avoid spiral point in soft aluminium (it bunches chips inside the hole). Lubricant: Tap Magic Aluminium variant — formulated to prevent the gummy build-up that aluminium causes on standard cutting fluids. Cast iron (grey, ductile, malleable) Drill: HSS Sutton D102 Blue Bullet (steam-oxide). Cast iron is brittle and abrasive — the steam oxide finish helps prolong drill life. Tap: Straight Flute tap (T4xx series) or hand tap. Cast iron breaks into powder rather than chips, so spiral evacuation isn't needed — straight flute is more rigid and handles the abrasiveness better. Lubricant: Generally tapped DRY — no cutting fluid needed for cast iron because chips are powder, not strings. Hardened steel (above ~30 HRC) For anything above mild steel hardness — pre-hardened tool steels, heat-treated parts, hardfaced surfaces — call AIMS before you start drilling. Solid carbide drills + thread mills are the right answer here, not standard taps. Contact us or call (02) 9773 0122 — we'll save you broken taps and damaged workpieces. The AIMS workshop rule: The right cutting fluid is worth more than the right tap. Even a premium Sutton tap will fail prematurely if you're tapping stainless without proper lubrication. Tap Magic cutting fluid guide covers which formulation matches your material. BSP Tap Drill Size Chart (British Standard Pipe) BSP threads are used on pipe fittings, hydraulic connections, and pneumatic systems throughout Australia and the UK. Sizes refer to the nominal bore of the pipe — not the actual thread diameter, which is always larger. BSPP (parallel) and BSPT (taper) share the same thread form and the same tap drill size. Need help finding your size? Call AIMS on (02) 9773 0122 — the team can confirm stock and pick the right tap type for your job. Or browse all BSP taps and jobber drill bits. Nominal Size TPI Tap Drill (mm) Tap Drill (inch) 1/16" BSP 28 6.6 0.261" 1/8" BSP 28 8.8 0.347" 1/4" BSP 19 11.8 0.465" 3/8" BSP 19 15.0 0.590" 1/2" BSP 14 18.6 0.733" 3/4" BSP 14 24.3 0.956" 1" BSP 11 30.5 1.200" 1¼" BSP 11 39.2 1.544" 1½" BSP 11 45.1 1.776" 2" BSP 11 57.0 2.245" 2½" BSP 11 72.6 2.858" 3" BSP 11 87.8 3.457" The 1/4" BSP tap drill size (11.8mm) is one of the most commonly referenced in Australian trade and industrial work. If you're unsure whether your fitting is BSPP or BSPT, the tap drill size is the same for both — the distinction only matters when selecting the tap itself. UNC Tap Drill Size Chart (Unified National Coarse) UNC is the standard US coarse thread series. Common in imported machinery, agricultural equipment, and items manufactured to American standards. Identified by thread count in threads per inch (TPI). Need help finding your size? Call AIMS on (02) 9773 0122 — the team can confirm stock and pick the right tap type for your job. Or browse all UNC taps and jobber drill bits. Thread TPI Tap Drill (mm) Tap Drill (fractional inch) #4-40 40 2.4 3/32" #5-40 40 2.65 --- #6-32 32 2.8 7/64" #8-32 32 3.5 9/64" #10-24 24 3.9 5/32" 1/4"-20 20 5.1 13/64" 5/16"-18 18 6.9 17/64" 3/8"-16 16 7.9 5/16" 7/16"-14 14 9.4 3/8" 1/2"-13 13 10.7 27/64" 9/16"-12 12 12.3 31/64" 5/8"-11 11 13.5 17/32" 3/4"-10 10 16.7 21/32" 7/8"-9 9 19.4 49/64" 1"-8 8 22.2 7/8" 1-1/8"-7 7 25.4 1" 1-1/4"-7 7 28.6 1-1/8" 1-3/8"-6 6 31.0 1-7/32" 1-1/2"-6 6 34.1 1-11/32" UNF Tap Drill Size Chart (Unified National Fine) UNF has a finer pitch than UNC — more threads per inch, higher tensile strength, and better vibration resistance. Used in aerospace, precision equipment, and anywhere a finer thread is specified. When in doubt, check the thread count: more threads per inch means UNF. Need help finding your size? Call AIMS on (02) 9773 0122 — the team can confirm stock and pick the right tap type for your job. Or browse all UNF taps and jobber drill bits. Thread TPI Tap Drill (mm) Tap Drill (fractional inch) #4-48 48 2.3 3/32" #6-40 40 2.9 7/64" #8-36 36 3.5 9/64" #10-32 32 3.8 9/64" 1/4"-28 28 5.6 7/32" 5/16"-24 24 6.9 17/64" 3/8"-24 24 8.5 21/64" 7/16"-20 20 9.9 25/64" 1/2"-20 20 11.5 29/64" 9/16"-18 18 13.1 33/64" 5/8"-18 18 14.7 37/64" 3/4"-16 16 17.5 11/16" 7/8"-14 14 20.6 13/16" 1"-12 12 23.4 59/64" 1-1/8"-12 12 26.6 1-3/64" 1-1/4"-12 12 29.8 1-3/16" 1-3/8"-12 12 33.0 1-5/16" 1-1/2"-12 12 36.5 1-7/16" Related AIMS Selectors & Guides This page sits at the centre of AIMS's threading and drilling tool cluster. The related selectors and selection guides below go deeper on the choices around it: Tap & Die Selection Guide — what tap type for which material, hole type, and machine Drill Bit Selection Guide — HSS vs cobalt vs carbide, jobber vs stub vs reduced shank Cutting Speeds & Feeds Reference — Vc and feed rate by material and tool type Cutting Tool Materials — HSS, cobalt, carbide, PCBN, PCD compared Cutting Tool Coatings — TiN, TiAlN, AlCrN, when each matters Cutting Tool Troubleshooting — broken taps, walking drills, poor finish, oversize holes Metric / Imperial / Gauge Conversion Master Chart — full drill bit + thread size cross-reference Thread Standards: BSP vs NPT vs UNC — identify the thread system you're dealing with Or browse the full taps range + jobber drill bits + cobalt drill bits — Sutton primary stock, Bordo and P&N alternates, specialty brands available for next-day Australia-wide dispatch from our Milperra warehouse.Frequently Asked Questions What drill size for M3 tap? For M3 coarse thread (0.5mm pitch), use a 2.5mm tap drill. For M3 fine (0.35mm pitch), use a 2.65mm drill. Formula: 3 − 0.5 = 2.5mm. What drill size for M4 tap? For M4 coarse thread (0.7mm pitch), use a 3.3mm tap drill. For M4 fine (0.5mm pitch), use a 3.5mm drill. Formula: 4 − 0.7 = 3.3mm. What drill size for M5 tap? For M5 coarse thread (0.8mm pitch), use a 4.2mm tap drill. For M5 fine (0.5mm pitch), use a 4.5mm drill. Formula: 5 − 0.8 = 4.2mm. What drill size for M6 tap? For M6 coarse thread (1.0mm pitch), use a 5.0mm tap drill. For M6 fine (0.75mm pitch), use a 5.25mm drill. Formula: 6 − 1.0 = 5.0mm. What drill size for M8 tap? For M8 coarse thread (1.25mm pitch), use a 6.8mm tap drill. For M8 fine (1.0mm pitch), use a 7.0mm drill. Formula: 8 − 1.25 = 6.75mm, rounded to 6.8mm. What drill size for M10 tap? For M10 coarse thread (1.5mm pitch), use an 8.5mm tap drill. For M10 fine (1.25mm pitch), use 8.75mm; for M10 fine (1.0mm pitch), use 9.0mm. Formula: 10 − 1.5 = 8.5mm. What drill size for M12 tap? For M12 coarse thread (1.75mm pitch), use a 10.2mm tap drill. For M12 fine (1.5mm pitch), use 10.5mm; for M12 fine (1.25mm pitch), use 10.75mm. Formula: 12 − 1.75 = 10.25mm, rounded to 10.2mm. What drill size for M14 tap? For M14 coarse thread (2.0mm pitch), use a 12.0mm tap drill. For M14 fine (1.5mm pitch), use 12.5mm. Formula: 14 − 2.0 = 12.0mm. What drill size for M16 tap? For M16 coarse thread (2.0mm pitch), use a 14.0mm tap drill. For M16 fine (1.5mm pitch), use 14.5mm. Formula: 16 − 2.0 = 14.0mm. What drill size for M20 tap? For M20 coarse thread (2.5mm pitch), use a 17.5mm tap drill. For M20 fine (2.0mm pitch), use 18.0mm; for M20 fine (1.5mm pitch), use 18.5mm. Formula: 20 − 2.5 = 17.5mm. What drill size for 1/4 inch BSP tap? The recommended tap drill for 1/4 inch BSP (19 TPI) is 11.8mm, or 0.465 inches. This applies to both BSPP (parallel) and BSPT (taper) threads — the tap drill is the same. What drill size for 1/8 inch NPT tap? The recommended tap drill for 1/8 inch NPT (27 TPI) is 8.6mm, or 21/64 inch. NPT is a tapered thread used on American pipe fittings — distinct from BSP. What drill size for 1/4 inch UNC tap? For 1/4-20 UNC, use a 5.1mm tap drill (13/64 inch). UNC has 20 threads per inch and is the standard US coarse thread. How do I calculate tap drill size for metric threads? Tap drill size (mm) equals thread diameter minus thread pitch. Example: M10 × 1.5 = 10 − 1.5 = 8.5mm. This gives approximately 75% thread engagement, which is standard for most applications. What is a tap drill size? A tap drill size is the diameter of the hole you drill before cutting a thread with a tap. It must be smaller than the thread's outer diameter so the tap has material to cut the thread profile into. What is the difference between BSPP and BSPT? BSPP (British Standard Pipe Parallel) has straight threads and seals with an O-ring or washer. BSPT (British Standard Pipe Taper) has a tapered thread that seals as it tightens. Both share the same tap drill size for a given nominal size, but BSPT taps are designed to cut a taper. If a tap breaks during the threading process, see our guide on how to remove a broken tap — covering all six removal methods from tap extractors through to EDM. Ready to tap? Shop our full range of taps, dies & threading tools From metric hand taps to imperial die sets — AIMS Industrial stocks threading tools for every standard, ready to ship Australia-wide. Browse taps Talk to a specialist For the tap type that matches your hole and material, see our Tap Types Explained guide. For choosing the right cutting fluid for your material, see our Tap Magic cutting fluid guide. Need to identify a thread standard? Our Thread Standards Guide covers BSP, NPT, UNC, UNF, BSW and metric with identification tips. People Also Ask — Tap Drill Size Chart: Metric & Imperial Thread Sizes Q: What drill size do I use for an M10 tap? For M10 × 1.5 coarse thread, use an 8.5 mm pilot drill. For M10 × 1.25 fine thread, use a 8.75 mm drill (often rounded to 9.0 mm in practice). Using the correct pilot hole is critical — too small risks tap breakage; too large produces insufficient thread engagement and weak joints. Q: What is the difference between a taper tap and a plug tap? A taper tap has a long chamfer (8–10 threads) that guides it into the hole gradually — best for starting threads in blind or through holes. A plug tap (4–5 thread chamfer) picks up where the taper left off and is the most common general-purpose tap. A bottoming tap has just 1–2 threads of chamfer for cutting threads to the very bottom of a blind hole. Q: What is the difference between BSP and NPT threads? BSP (British Standard Pipe) uses a 55° thread angle and is the standard for most Australian, British, and European hydraulic and pneumatic fittings. NPT (National Pipe Taper) uses a 60° thread angle and is common on American equipment. The two are not interchangeable — mismatching causes leaks and can damage fittings even if they appear to thread together. Q: How do I know which tap size to buy? Match the tap to the bolt thread you need — an M6 × 1.0 tap cuts the thread for an M6 coarse bolt. Always pair taps with the correct pilot drill from a tap drill chart. For blind holes, buy a taper, plug, and bottoming tap set. For through holes, a plug tap alone is usually sufficient for most trade applications. For machining, see our machining range stocked across Australia. Looking for long drill bits? Our long drill bits range covers the common sizes and brands.
Read more
Weld Like A Pro With CRC Weld-Aid®
The new and improved Weld-Aid® product range is “engineered to improve your welding productivity”, so you can do easier and cleaner welds. They are specifically designed for MIG welding. Nozzle-Kleen Nozzle-Dip HD Nozzle-Kleen #2 Weld-Kleen Weld-Kleen HD Weld-Kleen Anti-Spatter 350 Lube-Matic Wire Kleener and Lubricant Kleener Pads (Red) Lube Pads (Black) Combo Pack (Red and Black) Nozzle-Kleen This product group consists of the Nozzle Dip HD and Nozzle Kleen #2. These are engineered to prevent, reduce and remove spatter build-up on your welder nozzles, tips and diffusers, so you can use them longer. Nozzle-Dip HD It will neither clog your torch, nor contaminate your weld like petroleum jelly (from which most conventional nozzle dips are made), thanks to its unique water-based gel formulation. More benefits: Effectively cools your nozzles and tips Reduces spatter build-up Works on both hot and cold torches Does not drift into the liner Water-based Biodegradable Non-flammable Non-hazardous Non-flashing Non-toxic Paintable Buy the CRC Nozzle-Dip HD. Nozzle-Kleen #2 All you need is a light spray of "the world’s best-selling anti-spatter aerosol” on the nozzle, and you can start welding right away. More benefits: Can be used even on surfaces to be welded Spatter can easily be wiped away No need to scrape or grind the finish Leaves less smoke and odor Dries quickly Does not contain fluorocarbons Non-flammable Paintable Buy the CRC Nozzle-Kleen #2. Weld-Kleen This product group consists of the Weld-Kleen HD and Weld-Kleen Anti-Spatter 350. Use them if you want to spend more time welding and less time on grinding and cleaning up spatter. Weld-Kleen HD It protects your welder’s parts as well as your clamps, tooling and other fixtures with its heavy-duty base metal treatment. More benefits: Accepts pre-heating Dries quickly Non-flammable Paintable Buy the CRC Weld-Kleen HD. Weld-Kleen Anti-Spatter 350 It has a “superior performance versus other water-based anti-spatters". More benefits: Available in non-pressurized and pressurized (aerosol) dispensers Spatter just wipes away (no need to scrape and grind) Effective for use in torch blow-down systems Ready to use, no need to mix Environmentally friendly Biodegradable Non-hazardous Non-toxic Paintable Buy the CRC Weld-Kleen Anti-Spatter 350. Lube-Matic This product group consists of the Wire Kleener and Lubricant and Kleener Pads. Use them if you want to improve the lifespan of your tips and liners for up to 300%. Wire Kleener and Lubricant This easy-to-use welding wire cleaner and lubricant is designed to promote smoother wire feeding (specifically, fabricated and mild steel wires) by reducing drag and friction from the feeder to your welder. It is applied to Kleener Pads as needed (see below). More benefits: Decreases downtime caused by wire jamming Helps feed fabricated and mild steel wires Reduces wire drag by up to 60% Removes dirt Cuts rusts Buy the CRC Wire Kleener and Lubricant. Kleener Pads (Red) and Lube Pads (Black) Applied with the Wire Kleener and Lubricant, these pads will help keep your wires thoroughly cleaned and lubricated to maximise your torch’s effectiveness and lifespan. You can buy them separately or as a bundle. More benefits of Kleener Pads (Red): Reduce burnback by up to 50% Effective for all wire types Excellent with aluminium Buy the CRC Kleener Pads (Red). More benefits of Lube Pads (Black): Effective pre-treatment for smoother feeding of wires with poor cast, helix and rust Good for long feed liners Best used for the pre-treatment of wires Can be used on all types of steel wires (but not recommended with aluminium) Buy the CRC Lube Pads (Black). *Need help with a purchase decision? Contact us directly via chat or send an email to sales@aimsindustrial.com.au or call us on (02) 9773 0122 Need welding gear? The AIMS Welding collection covers everything from entry-level inverters to multiprocess welders. AIMS stocks a comprehensive Lubrication collection — Loctite, Anglomoil, Macnaught, Triple7 and CRC products. Share: Share on Facebook Share on X Pin on Pinterest Previous Post Does CRC Evapo-Rust Actually Work? Next Post Choosing the Right Drive Size for Sockets Looking for butt weld fittings? Our butt weld fittings range covers the common sizes and brands. Related Posts bordo Reciprocating Saw Blade Guide: TPI Selection, Bi-Metal vs Carbide, Wood/Metal/Demolition Blade Choice May 11, 2026 AIMS Industrial bsp Grease Nipple & Zerk Fitting Guide: Thread Sizes, Types, BSP vs UNF & How to Identify May 11, 2026 AIMS Industrial bolt-extractor Bolt Extractor Guide: Easy-Outs, Spiral Flute, Multi-Spline & Bolt Extractor Sockets May 11, 2026 AIMS Industrial People Also Ask — Weld Aid Anti-Spatter Products Q: What does weld spatter protection spray do? Weld anti-spatter spray is applied to the workpiece and surrounding areas before welding to prevent molten metal droplets from adhering to the surface. After welding, spatter falls away cleanly instead of bonding to the steel, dramatically reducing post-weld clean-up time and protecting adjacent surfaces from surface contamination. Q: Can weld anti-spatter be used inside the MIG gun nozzle? Yes, nozzle-dip anti-spatter products are specifically formulated for applying to or dipping the MIG gun nozzle to prevent spatter build-up inside the nozzle and on the contact tip. This extends nozzle and tip life, maintains shielding gas flow and reduces downtime for nozzle cleaning during extended welding operations. Q: Is weld anti-spatter spray safe to use on stainless steel? Standard petroleum or silicone-based anti-spatter products should not be used on stainless steel that will be painted or coated afterward, as silicone contamination causes fish-eye defects in coatings. Water-based or silicone-free anti-spatter products are available specifically for stainless steel applications. Q: How should anti-spatter spray be applied for best results? Apply a thin, even coat to the workpiece surface before welding, allowing it to flash off briefly if specified by the manufacturer. Avoid spraying directly onto the weld zone or joint gap as this can contaminate the weld and cause porosity. Nozzle dip products should coat the inside of the nozzle without blocking the gas outlet holes.
Read more
Does the CRC Evapo-Rust Really Work
CRC Evapo-Rust is a best-seller for many reasons. In this article, we answer these questions: What’s your opinion about the product? Does the CRC Evapo-Rust really work? How does it work? How much do I need to use? Do I need to fully submerge the whole item, or just the rusted surfaces? Will it corrode the rusted metal and other non-metal components? How long do I need to soak the rusted metal in it? Do I need to sand or scrub the rusted item after soaking it in? Can I reuse the liquid solution? Is it flammable? Is it harmful, hazardous and toxic? Feedback from users in real-life applications Disclaimer: The information compiled here is based on actual experience and diligent research. Nevertheless, it should not be treated as professional advice. As always, read the label and proceed with caution. What’s your opinion about the product? One Friday afternoon, our Sales Manager, Sam, soaked a bunch of rusted sprockets in Evapo-Rust solution. He took photos of the progress of what happened after soaking them (1) after two hours and (2) over the weekend. (He also brought a pair of pliers riddled with saltwater rust, which we also covered further below.) Quick verdict: Evapo-Rust works! Rusts gone. Here are the rusted sprockets before soaking. As you can see, some of them are heavily rusted on the surface, while some are not: Here they are after being soaked in pure Evapo-Rust after two hours: Comparison of the “untreated” (top-half) and “treated” (bottom-half) after being soaked for two hours: Here they are after being soaked into pure Evapo-Rust over the weekend: Most came off visibly “rust-free” after some thorough wiping, although Sam had to lightly steel-brush a few ones “to speed up the process” and get the same rust-free result. According to Sam: “I used CRC Evapo-Rust with some great results. The photos are time-lapse as well to show the different results. In short, the longer we leave product in solution, the better the results.” “Rusty sprockets will pose a problem if they are installed as they are. They will work, but the addition of grease will contaminate the lubricant and add to chain and sprocket wear. The trick is to keep the lubricant clear of any contaminants and prolonging the life of all wearing parts. Rust also destroys surface hardness and will accelerate wear." Does the CRC Evapo-Rust really work? The quick answer is a yes. It is designed to do one job -- remove rust -- and it does it well, provided, of course, that you use it properly and according to instruction. Here’s the CRC Evapo-Rust in action: It “effectively removes even deep rust on all types of mild steels and iron”. According to the technical data sheet, you should use the product as follows: Pre-clean item to remove oil and dirt. Rinse item and immerse item fully in Evapo-Rust for 20 minutes. Check progress periodically. Once rust is removed, rinse the item with water. To prevent re-rusting, simply dip the item back in Evapo-Rust solution and allow it to dry. Note: Deeply rusted parts (5 mm or deeper) may require overnight soaking. Evapo-Rust can be used over and over until performance drops off. When ready to dispose of spent solution, only the iron content of the solution will dictate disposal method. In most cases, it can be safely put down the drain. How does it work? EVAPO-RUST® works through selective chelation. This is a process in which a large synthetic molecule forms a bond with metals and holds them in solution. Most chelating agents bind many different metals. The active ingredient in EVAPO-RUST® bonds to iron exclusively. It can remove iron from iron oxide but is too weak to remove iron from steel where the iron is held much more strongly. Once the chelating agent has removed the iron, a sulfur-bearing organic molecule pulls the iron away from the chelator and forms a ferric sulfate complex which remains water soluble. This frees the chelating agent to remove more iron from rust. More tips from the technical data sheet c/o crceurope.com: If EVAPO-RUST® is used below 15°C, cleaning times will be extended. Warmer temperatures will improve rust removal capabilities. Store cool (above 0°C) and dry. How much do I need to use? That depends a lot on: Which product you are using: the spray gel or the liquid solution How many items you want to de-rust How rusted are the items in question How long you "soak” the items in its chemical While both the spray gel and liquid solution basically have the same formulation, the spray gel “clings” to the surface of the item in question so there’s no need to soak it. If you have the liquid solution, use it pure and undiluted. It’s ready to use right off the bottle, and there is no need to mix with water. In Sam’s experiment, he took a 5-litre Evapo-Rust solution container to fully submerge around 100 kilograms of sprockets of various sizes. (Fun fact: According to Microsoft Word, 100 kilograms is around the weight of an average professional basketball player.) Sam said he was able to “salvage back in the container about ¾ of the Evapo-Rust solution”. Do I need to fully submerge the whole item, or just the rusted surfaces? You only need to submerge the rusted areas. If the whole item is badly rusted all over, then yes, you’ll want to submerge it altogether, especially if it’s badly eaten by rust just like the tools and components in this video by CRC NZ: Will it corrode the rusted metal and other non-metal components? EVAPO-RUST® is safe to use on (not harmful to): Aluminium Brass Copper Non-oxide-based paints Plastics PVCs Rubber Vinyl In fact, Sam has another example, this time with his rusty pliers -- that he uses for fishing, so it is riddled with saltwater rust -- that are seized up and wouldn't spring open. After soaking them in 're-used' EVAPO-RUST® solution for two hours a soaking and a some mild cleaning up with a wire brush, he was happy with the result: How long do I need to soak the rusted metal in it? That depends a lot on how badly rusted parts are. In Sam’s experiment, the sprockets’ surfaces were significantly “rust-free” after a two-hour soak in pure EVAPO-RUST® but note that they are not heavily rusted to begin with. (He waited it out for another two days.) Do I need to sand or scrub the rusted item after soaking it in? Sam had to lightly brush off a few sprockets to achieve the desired result. Can I reuse the liquid solution? According to CRC’s video above, the technical data sheet and Sam's pliers example, yes you can reuse the solution “until the performance drops off”. Is it flammable? It is “non-caustic”, “non-flammable” and “contains no flammable materials”. We reckon the same is true for the liquid solution. However, keep in mind that it’s still a chemical product best kept away from obvious heat sources and open flames. Is it harmful, hazardous and toxic? Please use common sense and observe safety precautions when using the product, but for the record: According to the backside label of both the spray gel and liquid solution, they are “not classified as toxic material”, do not contain “acids, alkalis and petroleum” and are not harmful to the user and the environment. According to the safety data sheets of both the spray gel and liquid solution, they are “not classified as hazardous” as per Safe Work Australia criteria. According to the technical data sheet, they are “safe to use” and contain “no acids, hazardous air pollutants (HAPs) and volatile organic compounds (VOCs)”. Both have no strong fumes and odours that can cause irritation under normal conditions. Of course, it’s always best to take extra precautions if you have relevant pre-existing allergies and respiratory conditions. It has no food safety certification, although you can use it on parts of food equipment as long as it doesn’t directly come into contact with the food itself. Make sure to wash it off and dry completely before use. Buy Evapo-Rust now. Feedback: Ken H from Perth shared his experience with the CRC Evapo-Rust: "I have used it on a couple of things, and have had brilliant results. I have just restored two old motorcycles to "as new" condition, and for most of the components a wire buff or grit blasting worked well. But there are a few components which were too delicate for that. One in particular was the tool box on my 1963 A10 BSA. The sheet steel it is made from is too old/delicate to use grit blasting. The corners and confines make the wire wheel either inaccessible, or dangerous, as it catches on edges. Any acidic medium (if left too long) would dissolve it. Now, these tool boxes are NO LONGER AVAILABLE. They make them in India, and they are either poor quality or just don't fit. Too hit and miss. A second hand one in terrible condition (worse than mine was) sells for $300 - $400 AUD. So I HAD to save mine. Evapo-Rust was safe, and can be left as long as you like, as it DOES NOT DISSOLVE BASE METAL. The greatest point to remember is that Evapo-Rust saturates during use, and it does not convect / self-circulate. So, it will turn black (in areas close to the rust surface) as it absorbs rust, and then stays there against the surface / will not absorb any more. Once saturated, it is no longer of any use = dispose of it. The best way is to either "stir / circulate" the liquid, or (in a corner where the liquid is "black" and thus saturated) drawn off with a syringe and disposed of / allow unsaturated liquid to continue to work. See the attached pictures. Before and after: That tool box had sat on that bike for 40 years and had bad chrome with rust pitting under it, rust inside. Evaopo-Rust cleaned it enough for priming and painting. I also used it on a Triumph Stag bumper (very hard to get, they make replacements which are nowhere near as good as the original) to remove rust from the rear of it before preservation. The outside is chrome, but the inside barely treated, so they rust. The Evapo-Rust removes the inside surface rust, with no damage to existing chrome. It is a brilliant product. Share: Share on Facebook Share on X Pin on Pinterest Previous Post Choosing the Right Tap for Your Drilling Application Next Post Weld Like A Pro With CRC Weld-Aid® Related Posts bordo Reciprocating Saw Blade Guide: TPI Selection, Bi-Metal vs Carbide, Wood/Metal/Demolition Blade Choice May 11, 2026 AIMS Industrial bsp Grease Nipple & Zerk Fitting Guide: Thread Sizes, Types, BSP vs UNF & How to Identify May 11, 2026 AIMS Industrial bolt-extractor Bolt Extractor Guide: Easy-Outs, Spiral Flute, Multi-Spline & Bolt Extractor Sockets May 11, 2026 AIMS Industrial People Also Ask — Does the CRC Evapo-Rust Really Work Q: How does Evapo-Rust work to remove rust? Evapo-Rust uses selective chelation — a process where chelating agents bond to iron oxide (rust) molecules and hold them in solution, lifting them off the base metal without attacking the underlying iron or steel. It is water-based, non-toxic, non-flammable, and biodegradable. Unlike acid-based rust removers, it does not etch bare metal, making it safer for use on precision parts. Q: How long should I soak parts in Evapo-Rust? Light rust (surface oxidation): 30 minutes to 2 hours. Moderate rust: 4–8 hours. Heavy rust with pitting: overnight or up to 24 hours. Agitation (brushing or sloshing every hour) speeds up the process. Parts must be fully submerged. The solution turns dark brown as it absorbs rust — it can be reused until it stops working effectively (typically after removing approximately 300 g of rust per litre). Q: What is the best CRC product for long-term rust protection? For long-term storage protection, CRC SP-400 or CRC Dry Film PTFE provide durable barrier protection. For active corrosion prevention in wet or marine environments, CRC SP-350 (a heavy wax-based inhibitor) is preferred. CRC 2-26 is excellent for moisture displacement and contact protection but provides limited long-term film durability — apply monthly in harsh environments. Q: Can I use Evapo-Rust on chrome or aluminium parts? Evapo-Rust is safe on steel and iron and will not damage chrome plating, aluminium, copper, brass, solder, or most plastics during normal soak times (up to 24 hours). However, it is not effective at removing rust from aluminium — aluminium forms aluminium oxide, not iron oxide, and the chelating agents in Evapo-Rust are selective to iron. For aluminium oxidation, use an aluminium-specific cleaner.
Read more
Tap Types Explained: Taper, Plug, Bottoming, Spiral Point & Flute
Choosing the right tap looks simple until you've snapped one off in a $400 casting. Then you find out the hard way that taper, plug, bottoming, spiral point and spiral flute taps aren't interchangeable — each does a specific job, and using the wrong one in the wrong hole is the fastest route to a broken tool. This guide walks you through every tap type Australian tradies and machinists actually use, with the forum-tested rules for matching the tap to the job. Tap Types — Quick Reference Tap Type Best For Chip Direction Hole Type Taper tap Starting threads by hand Sideways (straight flute) Through or blind (start only) Plug tap General-purpose threading Sideways (straight flute) Through holes Bottoming tap Full threads to base of blind hole Sideways (straight flute) Blind holes (after starter tap) Spiral point (gun) Production tapping in a machine Forward (ahead of tap) Through holes only Spiral flute Blind holes in tough materials Backward (out of hole) Blind holes only Forming (roll) tap Strongest threads, ductile materials No chips (cold-forms) Through or blind The single most common forum mistake: putting a spiral point (gun) tap in a blind hole. The chips have nowhere to go — they pack up at the bottom and snap the tap. Gun taps need somewhere for chips to exit ahead of the cutting flutes. For blind holes, use a spiral flute tap instead. For tap drill sizes, see our Tap Drill Size Chart. For thread standards (BSP, NPT, UNC, UNF, metric), see our Thread Standards Guide. What Is a Tap? A tap is a hardened cutting tool used to create internal threads in a pre-drilled hole. The tap is essentially a precision-ground threaded rod with cutting edges along its length. As you rotate it into a hole sized correctly for the tap, the cutting edges remove material to form the thread profile. Three things define every tap: Thread profile — metric M-series, UNC, UNF, BSW, BSP — must match the thread standard you want to cut. See our Thread Standards Guide for the differences. Chamfer length — the tapered cutting section at the start of the tap. Long chamfer (4–8 threads) for starting, short chamfer (1–2 threads) for cutting threads to the bottom of a blind hole. Flute design — straight, spiral point, or spiral flute. This determines where the chips go as you cut. Match all three to the job and you'll cut clean threads first time. Get one wrong and you'll likely break the tap, strip the thread, or get a hole you can't use. The Three Classical Hand Taps — Taper, Plug, Bottoming Most threading is still done with the traditional set of three straight-flute hand taps. The only difference between them is the length of the chamfered cutting section at the tip — the threads themselves are identical. Taper Tap (4–8 chamfered threads) The taper tap has the longest cutting chamfer — typically 7 to 10 threads of taper at the tip, gradually working up to full thread depth. The long taper does two things: Makes it easy to start the thread square to the hole by hand Distributes the cutting load across many threads, reducing torque and breakage risk Taper taps are the safest tap to start a thread with, especially for tradies tapping by hand without a guide. The trade-off is that you can't cut full threads to the bottom of a blind hole — the tapered tip means the last 7 threads at the bottom are progressively shallower. Plug Tap (3–5 chamfered threads) The plug tap (sometimes called the "second tap") has a shorter chamfer than the taper — usually 3 to 5 threads. It's the workhorse of hand tapping: For through holes, you can start and finish with just a plug tap For blind holes, use it as the second pass after the taper tap to deepen the threads For machine tapping straight-flute work, plug is typically the default If you're only going to buy one hand tap of a given size, make it a plug. Bottoming Tap (1–2 chamfered threads) The bottoming tap has almost no chamfer — usually just 1 to 2 threads of cutting taper at the tip. This lets it cut full threads right down to the bottom of a blind hole. Critical detail tradies often get wrong: a bottoming tap cannot start a thread on its own. With only 1–2 threads of chamfer, it doesn't have the lead-in to stay square in a hole. You must always start with a taper or plug tap first, then finish with the bottoming tap. If you put a bottoming tap into a fresh hole and try to cut threads with it from scratch, it will skate sideways, chip, or break. When to Use Each — Decision Logic Situation Sequence Through hole, easy material Plug tap only Through hole, tough material Taper → plug Blind hole, threads not needed at base Taper → plug Blind hole, full threads to base required Taper → plug → bottoming Hand tapping a sensitive material first time Always start with taper Hand tap sets sold in Australia typically come as a three-piece set (taper, plug, bottoming) in each thread size — see our Imperial Hand Taps and Tap and Die Sets collections. Spiral Point vs Spiral Flute — The #1 Confusion This is the question that breaks more taps than any other: spiral point and spiral flute taps look almost identical, and tradies who haven't worked with both can't tell them apart in a tool drawer. They are designed for opposite jobs. Get them mixed up and you'll snap a tap inside a workpiece. Spiral Point Tap (also called Gun Tap, Bull Nose Tap) A spiral point tap has straight flutes along its length, but the cutting chamfer at the tip is ground with a slight angled "point" geometry that pushes chips forward, ahead of the cutting edge. The chips clear out through the bottom of the hole. This makes spiral point taps brilliant for: Through holes — chips exit the bottom of the hole, never building up around the tap Production machine tapping — high speed, continuous rotation, no need to back off Soft and stringy materials like aluminium, brass and copper where chips tend to weld to a cutting tap Spiral point taps are also called "gun taps" because the chip-shooting action looks like a rifle barrel ejecting cartridges. Critical warning: NEVER use a spiral point tap in a blind hole. The chips have nowhere to go. They pack up at the bottom of the hole, the tap binds, and it snaps. This is the most common forum-reported broken-tap scenario. See our Metric Spiral Point Taps and Imperial Spiral Point Taps ranges. Spiral Flute Tap A spiral flute tap has helical flutes running along its length, similar to a drill bit. The helix direction pulls chips backward, out of the hole as the tap rotates. This makes spiral flute taps the right choice for: Blind holes — the upward chip flow keeps the bottom of the hole clear Tough materials like stainless steel, alloy steel, and titanium where good chip evacuation prevents work-hardening Deep threading where chips have a long way to travel before exiting Use a spiral flute tap in a through hole and you'll get a worse result than a plug — the helical chip flow pulls chips back through the cutting threads, sometimes re-cutting them. Spiral flute should mostly stay in blind-hole work. See our Metric Spiral Flute Taps and Imperial Spiral Flute Taps. How to Tell Spiral Point and Spiral Flute Apart Feature Spiral Point (Gun) Spiral Flute Flutes along body Straight (parallel to axis) Helical (twisted like a drill) Chamfer geometry Angled "point" at tip Standard cutting chamfer Chip direction Forward (out bottom) Backward (out top) Use in through holes ✓ Excellent ✗ Avoid Use in blind holes ✗ Will snap ✓ Excellent The visual giveaway is the flute geometry — if the flutes are straight (parallel to the tap axis), it's spiral point. If the flutes spiral around the tap like a drill bit, it's spiral flute. The chamfer geometry difference is harder to see without comparing two side by side. Hand Taps vs Machine Taps Hand taps and machine taps look similar but are engineered for different working conditions. Hand Taps Hand taps are designed for manual use with a tap wrench. They typically come as a three-piece set (taper, plug, bottoming) and have straight flutes for general-purpose threading. The expectation is that the user will rotate the tap forward 1/2 to 1 turn, then back off 1/4 to 1/2 turn to break the chip — this is essential for chip clearance with straight-flute geometry. Hand taps work fine in machine spindles too, especially for small-batch work. But for production tapping, machine taps cut faster and cleaner. Machine Taps Machine taps (also called CNC taps) are designed for continuous high-speed rotation in a tapping head, drill press, lathe, or CNC machine. They're typically: Spiral point or spiral flute (so they don't need backing off to break chips) Made from tougher materials (HSS-E cobalt, HSS-PM, or carbide) Often coated for higher cutting speeds Ground to tighter tolerances for repeatable thread quality If you're tapping the same thread hundreds of times a day, a machine tap pays for itself in cycle time and tool life. For one-off jobs or maintenance work, a hand tap set is more economical. Forming Taps (Roll Taps) — Cold-Forming Threads Forming taps (also called roll taps, fluteless taps or thread-rolling taps) are a fundamentally different way to make a thread. Instead of cutting and removing material, a forming tap displaces the workpiece material — it cold-forms the thread profile by pressing the metal into the thread shape. Forming taps have no flutes (no chip path is needed because there are no chips), no cutting edges, and a smooth polygonal cross-section that does the forming work. Advantages of forming taps: Stronger threads — the cold-worked metal grain follows the thread profile rather than being cut across it, increasing thread strength by 10–40% No chips — eliminates chip evacuation problems and chip welding in soft materials Longer tool life — no cutting edges to dull or break Higher feed rates — typically 30–50% faster than cutting taps Smaller tap drill — forming taps use a slightly larger pilot hole than cutting taps Strict limits — forming taps DON'T work on: Cast iron (brittle — will crack instead of forming) Hardened steel above ~30 HRC Most plastics (cold flow won't hold thread shape) Materials with less than ~5% elongation Forming taps are best suited to aluminium alloys, low-to-medium carbon steel, copper, brass (soft), and other ductile metals. See Metric Thread Forming Taps for our range. Tap Materials — HSS, HSS-E, HSS-PM, Solid Carbide The material the tap itself is made from determines its hardness, toughness, heat resistance, and price. Match the tap material to the workpiece material and the production rate. HSS (High-Speed Steel) HSS is the workhorse tap material. Tough, takes a sharp edge, holds up well to general-purpose threading in mild steel, aluminium, brass, plastics, and most workshop materials. M2 HSS is the most common grade. Affordable enough that breaking one isn't a disaster. Limitation: HSS softens at sustained cutting temperatures above ~600°C. Not the right pick for high-speed production work or work-hardening stainless steel. HSS-E (HSS-Co, Cobalt HSS) HSS-E adds 5–8% cobalt to HSS, increasing hot hardness — the ability to retain cutting hardness at high temperatures. This makes HSS-E better suited to: Stainless steel (which work-hardens and generates heat) Heat-resistant alloys Higher cutting speeds where HSS would soften Production tapping where consistent edge life matters HSS-E is typically 20–40% more expensive than plain HSS but lasts considerably longer in tough materials. HSS-PM (Powder Metallurgy HSS) HSS-PM is made by powder metallurgy rather than melted-and-rolled steel. The fine grain structure gives it better toughness than HSS-E with similar or higher hardness. Use cases: Very hard alloys Tool steel and die work High-precision tapping where edge consistency matters Bridge between cobalt HSS and solid carbide Premium price, but still tougher than carbide — won't shatter if you stall it. Solid Carbide Solid carbide taps are extremely hard and wear-resistant, designed for high-volume CNC tapping in difficult materials. They allow much higher cutting speeds than any HSS variant. The trade-off is brittleness — carbide will shatter if you stall it, side-load it, or hit a hard inclusion. Carbide taps need a rigid setup, precision-controlled feed, and a tap holder with sufficient tension/compression compensation. Not for hand tapping. Tap Coatings — Black Oxide, TiN, TiCN, TiAlN Surface coatings reduce friction, improve chip flow, and extend tap life. Common coatings you'll see on Australian shelves: Black oxide / steam tempered — a thin oxide layer that reduces galling in mild steel and improves lubricant retention. Cheap and reliable for general-purpose work. TiN (Titanium Nitride) — gold-coloured coating, ~2,300 HV hardness, good general-purpose coating that extends tap life in steel and stainless. TiCN (Titanium Carbonitride) — blue-grey or grey-purple, harder than TiN (~3,000 HV), good for cast iron and harder steels. TiAlN (Titanium Aluminium Nitride) — violet-grey or dark grey, very hard (~3,300 HV), excellent heat resistance — the premium choice for stainless, high-temp alloys, and hardened materials at high cutting speeds. For most workshop tapping, an uncoated or black-oxide HSS tap with proper cutting fluid is fine. Move up to TiN or TiAlN when you're tapping stainless, working at production rates, or running unattended CNC tapping cycles. How to Choose a Tap by Workpiece Material Material is the single biggest factor in tap selection. Get the material match right and you'll cut clean threads with a tap that lasts. Aluminium and Aluminium Alloys Aluminium tapping has one big problem: the chips weld to a hot HSS cutting tap and clog the flutes — known as "BUE" (built-up edge) on machinist forums. The result is a torn-looking thread with chunks of aluminium stuck to it. Fixes that work: Use a spiral point (gun) tap at higher cutting speed — gets chips out before they weld Use a forming tap — no chips at all, beautiful threads, ideal for aluminium Lubricate generously with kerosene, methylated spirits, or a dedicated aluminium-tapping fluid (see our Tap Magic cutting fluid guide for variant selection) — water-soluble coolants alone aren't enough Don't dwell — keep the tap moving so chips don't weld Mild Steel The easiest material to tap. HSS plug tap or spiral point (through holes), spiral flute (blind holes). General-purpose cutting fluid. Hand tapping or machine tapping both work well. This is what most workshop tapping looks like. Stainless Steel Stainless is the material that breaks more taps than any other — and forums are full of advice about it because most of that advice is wrong. The key facts: Stainless work-hardens. If the tap "rides" the surface without cutting (because it's dull, you're going too slow, or there's no cutting fluid), the surface hardens and the next tap breaks trying to cut into it. Use HSS-E (cobalt) or HSS-PM taps, not plain HSS. The hot hardness matters here. Use sulfurised cutting oil ("dark cutting oil") — water-based coolants alone aren't enough. The sulfur prevents chip welding. Spiral flute for blind holes, spiral point for through. Don't compromise here. Cutting speed: slower than you think. Roughly 1/3 to 1/2 the speed you'd use for mild steel. Engage the cutting edge immediately. Never let the tap idle on the surface. Cast Iron Cast iron tapping is the opposite of stainless — it cuts easily but throws abrasive dust instead of chips. Use: Straight-flute or spiral point HSS or HSS-E taps NO cutting fluid (cast iron is self-lubricating; fluid just turns dust to paste) Compressed air to clear chip dust Never use forming taps on cast iron — it's brittle and will crack instead of forming Brass and Bronze Brass is forgiving — almost anything works. Standard HSS plug tap, light cutting oil, moderate speed. Bronze is similar but harder, so prefer HSS-E for production work. Watch out for "gummy" brass alloys that grab the tap — back off frequently to break chips. Plastic For most plastics (acrylic, nylon, polycarbonate, ABS), use a sharp HSS tap with shallow chamfer, slow speed, and dry cutting. No forming taps (plastic creeps and won't hold a formed thread). For abrasive filled plastics (glass-filled nylon, carbon-filled), use a TiN-coated tap for better wear life. Why Taps Break — and How to Avoid It "Why do my taps keep breaking?" is the #1 forum question in tapping. The answer is almost always one of these: Wrong tap for the hole type. Spiral point in a blind hole = packed chips = broken tap. Bottoming tap as a starter = skating tap = broken tap. Wrong tap drill size. Too small a hole means the tap has to cut too much material per thread. Always verify against a Tap Drill Size Chart before drilling. No cutting fluid. Friction heat softens the tap, chips weld, breakage follows. Even on "easy" materials. Not backing off for chip break. Straight-flute hand taps need a 1/4 to 1/2 reverse turn for every 1 to 2 forward turns to break chips. Forget this and the chips pack up. Wrong material match. Plain HSS in stainless = work-hardened surface = broken tap on the next try. Use HSS-E or HSS-PM. Tap not square to the hole. Side-loading a tap as it cuts puts a bending stress that taps don't handle well. Use a tapping guide or set up in a machine. Forcing through resistance. If a tap suddenly gets harder to turn, STOP. Back it out, clear chips, check for binding, and continue. Don't crank harder. Riding the surface without cutting (stainless especially) — work-hardens the material and breaks the next tap. If you do break a tap, see our Screw Extractors for tap removal tools. Alternatives: EDM tap disintegration (specialist service), or carbide-burr the broken tap out (last resort, damages the thread). Tap Speed and Cutting Fluid Cutting speed for tapping is dramatically slower than for drilling. Approximate starting speeds for HSS hand taps: Material SFM Approx RPM for M10 Aluminium 50–100 500–1000 Brass / bronze 50–100 500–1000 Mild steel 30–60 300–600 Cast iron 20–40 200–400 Stainless steel 10–20 100–200 Tool steel (annealed) 10–20 100–200 HSS-E and HSS-PM taps can run 50–100% faster than these numbers. Solid carbide can run faster still, but only in rigid machine setups. Cutting fluid pairings: Mild steel, cast steel: standard tapping fluid or sulfurised cutting oil Stainless steel, alloy steel: sulfurised cutting oil ("dark oil") Aluminium: kerosene, methylated spirits, or dedicated aluminium-cutting fluid Brass, bronze: light mineral oil or dry Cast iron: dry (compressed air for chip removal) Plastic: dry, or water-based mist for filled plastics See Cutting Lubricants for our range. Sutton Tools — Australian-Made Cutting Tools Sutton Tools is Australia's largest manufacturer of HSS cutting tools, based in Thomastown, Victoria, and Australian-owned and operated since 1917. Their tap range is genuinely made in Australia (not just badged) — Sutton manufactures everything from the steel grinding through to coating in their Thomastown plant. The Sutton tap range covers: Premium HSS Blue series — bright, cobalt-tough, suited to mild steel, alloy steel and stainless Premium HSS Ni — for nickel alloys and tough stainless grades Tinite coated — TiN-coated for extended life R45 series — proprietary geometries for difficult materials (W, Al, VADH variants for steel, aluminium and high-strength materials) Spiral flute, spiral point and straight flute in metric (M3 to M30) and imperial (UNC, UNF, BSW, BSP) Sutton taps carry the Australian Made & Owned certification. For Australian Industry Capability (AIC), Buy Australian, mining local content and government procurement requirements, Sutton ticks every box. See our Sutton Tools collection or browse all our Taps. AIMS Tap Product Cross-Reference Sourcing taps and threading tools from AIMS Industrial by category: Hand taps (metric & imperial): Imperial Hand Taps Spiral point (gun) taps — metric: Metric Spiral Point Taps Spiral point (gun) taps — imperial: Imperial Spiral Point Taps Spiral flute taps — metric: Metric Spiral Flute Taps Spiral flute taps — imperial: Imperial Spiral Flute Taps Straight flute taps — metric: Metric Straight Flute Taps Straight flute taps — imperial: Imperial Straight Flute Taps Thread forming (roll) taps: Metric Thread Forming Taps Machine nut taps: Metric Machine Nut Taps | Imperial Machine Nut Taps Complete tap and die sets: Tap and Die Sets Thread identification gauges: Screw Pitch Gauges Tap extractors (broken tap removal): Screw Extractors Cutting fluids: Cutting Lubricants Full threading range: Threading Collection Related Reference Articles Tap Drill Size Chart — Metric & Imperial (drill size for every tap) Thread Standards Guide — BSP vs NPT vs UNC Tap Drill Diameters Explained — Major, Minor & Pitch Drill Bit Size Chart — Metric, Imperial, Fractional Repairing stripped threads rather than starting fresh? Our Stripped Threads Repair Guide walks the escalation ladder — re-tap, oversize, Helicoil, TimeSert and weld-up. Frequently Asked Questions What is the difference between a taper, plug and bottoming tap? The difference is the length of the chamfered cutting section at the tip. Taper taps have 7–10 chamfered threads (longest, easiest to start). Plug taps have 3–5 chamfered threads (most common general-purpose tap). Bottoming taps have only 1–2 chamfered threads, allowing them to cut full threads to the bottom of a blind hole — but they can't start a thread on their own; you must use a taper or plug first. What is the difference between a spiral point and a spiral flute tap? A spiral point (gun) tap pushes chips forward, ahead of the tap — use it in THROUGH holes only. A spiral flute tap pulls chips backward, up out of the hole — use it in BLIND holes only. The flute geometry on the tap body is the visual giveaway: straight along the axis = spiral point; helical like a drill bit = spiral flute. Using one in the wrong hole type is the #1 cause of broken taps. What is a gun tap? "Gun tap" is the common workshop name for a spiral point tap. The name comes from the way it ejects chips forward, ahead of the cutting edge, like a gun ejecting cartridges. Gun taps are ideal for through-hole production machine tapping. Never use them in blind holes — the chips will pack and snap the tap. Can a bottoming tap start a thread? No. A bottoming tap has only 1–2 threads of chamfer, which isn't enough lead-in to keep the tap square in a fresh hole. It will skate sideways, chip, or break. Always start the thread with a taper or plug tap first, then use the bottoming tap to finish the thread to the base of a blind hole. What tap should I use for aluminium? A spiral point (gun) tap for through holes, or a forming (roll) tap for either through or blind. Aluminium chips weld to a standard cutting tap as it heats up — gun taps clear chips fast enough to avoid this, and forming taps produce no chips at all. Use kerosene, methylated spirits, or a dedicated aluminium tapping fluid as lubricant. Never tap aluminium dry. What tap should I use for stainless steel? An HSS-E (cobalt HSS) or HSS-PM tap, ideally with TiAlN coating. Spiral flute for blind holes, spiral point for through. Use sulfurised cutting oil (dark cutting oil) — not water-based coolant alone. Cut at 1/3 to 1/2 the speed you'd use for mild steel, and never let the tap "ride" on the surface without cutting, or the stainless will work-harden and break your next tap. Why do my taps keep breaking? The most common causes are: spiral point tap in a blind hole (chips pack), wrong tap drill size (hole too small), no cutting fluid, not backing off chips with straight-flute hand taps, wrong material match (plain HSS in stainless), tap not square to the hole, or forcing through resistance. Stop the moment a tap suddenly gets harder to turn — clear chips, check alignment, and continue. Hand tap or machine tap — which do I need? For one-off jobs, maintenance work, and small production runs, hand taps (taper, plug, bottoming three-piece sets) used with a tap wrench or in a drill press are fine. For production tapping at high volume, machine taps (typically spiral point or spiral flute, HSS-E or coated) cut faster and don't require backing off. Hand taps work in machines too, just slower. What is a forming tap (roll tap)? A forming tap cold-forms the thread by displacing material — no cutting, no chips. The resulting thread is 10–40% stronger than a cut thread because the metal grain follows the thread profile. Forming taps work on ductile materials (aluminium, low-carbon steel, copper) but cannot be used on cast iron, hardened steel, brittle materials, or most plastics. They require a slightly larger pilot hole than cutting taps. What does HSS-E mean? HSS-E is high-speed steel alloyed with 5–8% cobalt (also called HSS-Co or "cobalt HSS"). The cobalt addition increases hot hardness — the tool's ability to retain hardness at elevated cutting temperatures. HSS-E taps last considerably longer than plain HSS in stainless steel, alloy steel and at higher cutting speeds. What is HSS-PM tap material? HSS-PM (Powder Metallurgy HSS) is high-speed steel made by powder metallurgy rather than melted-and-rolled steel. The fine, even grain structure gives it better toughness than cobalt HSS with similar or higher hardness. It sits between HSS-E and solid carbide in price and performance — used for tough materials, tool steel, and precision tapping where consistent edge life matters. What is the difference between a tap and a die? A tap cuts internal threads (in a hole). A die cuts external threads (on a rod or pipe). Tap-and-die sets pair both tools at matching thread sizes so you can create or repair both sides of a threaded joint. See our Tap and Die Sets for combined kits. Do I need cutting fluid when tapping? Yes — for almost every material except cast iron. Even on mild steel where the tap feels easy, cutting fluid extends tap life dramatically, improves thread surface finish, reduces breakage risk, and prevents chip welding. Cast iron is the exception — its graphite content makes it self-lubricating, and adding fluid turns the chip dust to abrasive paste. How fast should I tap? Tapping speed is much slower than drilling. As a starting point with HSS taps: aluminium and brass 50–100 SFM, mild steel 30–60 SFM, cast iron 20–40 SFM, stainless steel 10–20 SFM. HSS-E (cobalt) taps can run 50–100% faster. If a tap chatters, screams, or smokes, slow down and add cutting fluid. What does the "chamfer" of a tap mean? The chamfer is the tapered cutting section at the tip of the tap, where the cutting edges aren't yet at full thread depth. The chamfer length is what distinguishes taper taps (7–10 chamfered threads), plug taps (3–5), and bottoming taps (1–2). A longer chamfer is easier to start but can't cut threads near the bottom of a blind hole. People Also Ask — Tap Types Q: What are the three classical hand tap types and how do they differ? The three classical hand taps are taper, plug, and bottoming. A taper tap has the most chamfered lead threads, making it easiest to start but unable to cut to the bottom of a blind hole. A plug tap has fewer lead threads and is the most common general-purpose choice. A bottoming tap has just one or two lead threads and cuts threads to the very base of a blind hole. Q: What is the difference between a spiral point tap and a spiral flute tap? A spiral point (gun) tap pushes chips forward ahead of the cut and is used in through holes where chips can exit from the far end. A spiral flute tap pulls chips back up and out, suited to blind holes where chips cannot be pushed through. Using the wrong type in a blind hole is one of the most common causes of tap breakage. Q: What is a forming (roll) tap and when would you use it? A forming or roll tap displaces material to create threads rather than cutting them, producing no chips. This gives stronger threads and is well suited to ductile materials such as aluminium and low-carbon steel. Forming taps cannot be used in brittle materials, which will crack rather than form. Q: When should you use a machine tap rather than a hand tap? Machine taps are designed to run in a power tapping head, CNC machine, or cordless drill at controlled speed and feed. Hand taps are designed for manual use where the operator can feel resistance and reverse to break chips. Using a hand tap in a power machine without controlled feed typically results in tap breakage. Q: Why is starting with a taper tap important for hand tapping? The chamfered lead on a taper tap helps align the tap square to the hole before the cutting threads engage. Starting square is critical — a tap driven at an angle cuts a crooked thread and is prone to breakage, particularly in blind holes and harder materials. AIMS Industrial stocks machining — see the full range for trade and industrial use.
Read more
What's Inside the Fastener, Engineers and Electrical Black Books
In this article, we compiled: Contents of the Fastener Black Book (and metric-imperial specifics) Contents of the Engineers Black Book Contents of the Electrical Black Book Notes: The black books covered in this article are published by Pat Rapp Enterprises and exclusively distributed in Australia and New Zealand by Sutton Tools Pty Ltd. This compilation only provides a quick overview of information inside the books to help buyers decide which book(s) to buy. No copyright infringement is intended. Publisher's Note: "The content of the black books is for general informational use only and is not intended to be treated advice or opinion. Anyone using this document should rely on his or her own independent judgement or, as appropriate, seek the advice of a licensed competent professional in determining the exercise of reasonable care in any given circumstances." Contents of the Fastener Black Book The Fastener Black Book (First Edition) is a comprehensive reference guide for anyone who works with fasteners (engineers, designers, machinists etc). Here is a breakdown of the topics and information it contains: Basic fastener terminology: This includes definitions of common fastener components, types, and functions. Standards and specifications: You'll find explanations of thread forms, head and nut styles, along with various grading and marking systems used for fasteners. Material properties: The book covers common fastener materials like steel, aluminum, and plastic, along with their strengths and applications. Inch and metric equivalents: If you work with both inch-based and metric fasteners, this section will help you with conversions. Selection considerations: The Fastener Black Book provides information on factors to consider when choosing fasteners, such as thread fit, pre-load, and torque requirements. Special fasteners: There's also a section on self-tapping screws and other specialty fasteners. Identification tips: The book includes guidance on how to identify different fastener types and their properties. Visual aids: The Fastener Black Book may include charts, diagrams, and illustrations to aid understanding. This is the summary of contents of first edition for metric, which is still current: History of screw threads (that goes back to records from around 250 BC circa-Archimedes to the modern ISO standards we know today) Fastener Standards RoHS (Restriction of Certain Hazardous Substances) Introduction to threaded fasteners Basic fastener terminology (glossary) Basic fastener measurement Abbreviations for standard threads Common fastener thread forms, screw and bolt heads, head drives and features and thread points Common workshop bolts, nails, nuts, washers Self-drilling screw point selection guide Fastener materials (kinds of alloys and steels used) and mechanical properties Fastener corrosion, platings, coatings and finishes Fastener identification tips Fastener tensioning tips Common fastener failure (and how to avoid them) Comparison charts (tensile strength of steel vs alloy bolts, galvanic properties, hardness etc) Conversion charts (tightening torque values, PSI vs MPa, socket sizes, spanner selection, drill sizes) Counterboring, countersinking and clearance holes Conversion values (metric to inch/pound and vice versa) Fractional and decimal equivalents charts Tapping charts Also included as an accessory is a thread pitch identification gauge: Metric and imperial fastener specifics The Fastener Black Book colour-codes identifies measurements and sizes of metric fasteners in red and imperial fasteners in blue. Fastener specifications and cross-references: ANS (American National Standard) ISO (International Organization for Standardization) DIN (Deutsches Institut für Normung) (translates to German Institute for Standardization) *You might sometimes see DIN-ISO which refers to an ISO standard that has been adopted by Germany. Imperial fasteners cross-references: UNC (Unified National Coarse) UNRC (Unified National Round Coarse) UNF (Unified National Fine) UNRF (Unified National Round Fine) Most common kinds and types of fasteners are covered: Bolts Nuts Pins Rivets Screws (cap, machine, self-tapping, set, socket, tapping etc) Studs Washers It also provides comprehensive information on fastener properties: Stainless steel fasteners Aluminium fasteners Non-ferrous fasteners Plastic fasteners Contents of the Engineers Black Book The Engineer's Black Book (3rd Edition - Metric) is a comprehensive reference guide designed for engineers, machinists and other technical professionals. Here is a breakdown of the topics and information it contains: Conversion factors: These are essential for converting between different measurement systems, such as metric and imperial. Geometry formulas: A collection of formulas used in various geometrical calculations. Threads and feeds and speeds data: This section provides engineers with data on threads, including their dimensions and specifications, as well as recommended cutting speeds and feed rates for machining operations. Additional topics: Depending on the specific version, the Engineer's Black Book may also cover a broader range of topics, including: Materials science Welding Engineering drawing standards Tolerances Bolts and nuts Sharpening information Specific sections cover: Fundamentals and Reference Basic concepts: Brief history of engineering, common-sense safety at work; International System of Units (SI) and conversion factors; measurement and conversion tools (drills, spanners, sockets, torque); abbreviations, symbols and standards Mathematical and geometrical foundations: Trigonometry, geometry and algebra formulas; angles, radians and conversions; taper calculations and applications; coordinate systems and hole spacing Machining and Tooling Cutting tools and processes: Types, selection and applications of drills, reamers, end mills, hacksaw blades and bandsaw blades; drill point geometry, sharpening and speeds and feeds; coolants and lubricants; grinding wheels and mounted points Fasteners and joining: Types, sizes and properties of bolts, screws, nuts, washers and rivets; thread forms, tap types and tapping processes; retaining rings, O-rings and seals; welding and adhesive information (brief overview) Metrology and Quality Measurement and inspection: Measuring tools and techniques (sine bars, micrometers, calipers etc); tolerances, fits and surface finish; geometric dimensioning and tolerancing (GD&T) Materials and Metallurgy Material properties: Physical properties of metals, plastics and composites; material selection and comparison; heat treatment basics Tool materials: Tungsten carbide, ceramic, cermet, CBN and PCD cutting tool characteristics; coating technologies Mechanical Power Transmission Gears and gear trains: Gear geometry, calculations and standards; gear materials and manufacturing (brief) Bearings: Bearing types, selection and mounting Power Transmission Components: Belts, pulleys and shafts (basic concepts) Design and Drafting Engineering drawings: Basic drafting principles and standards; projection methods and dimensioning Design calculations: Formulas for areas, volumes and other geometric properties Note: This summary provides a general overview of the publication's content. Specific details and depth of coverage may vary. Contents of the Electrical Black Book The Electrical Black Book (2nd Edition) is a comprehensive reference guide designed for electricians, apprentices and anyone who wants to understand electrical systems better (or simply just anyone who wants to gain a better understanding of how electricity works). Here is an overview of the topics and information it contains: Electrical fundamentals: This includes the basic concepts of electricity, electrical safety principles, and electrical codes and standards. Electrical materials and equipment: You'll find information about conductors, conduits, transformers, motors, and other electrical components. Electrical calculations and formulas: The book provides formulas and conversion factors commonly used in electrical work. Electrical installations: This section covers electrical wiring methods, socket outlets, switches, and enclosures. Emerging technologies: The Electrical Black Book also touches on newer electrical technologies like LED lighting, fiber optics and data cabling. Specific sections cover: Introduction and Safety Historical overview: Brief history of electricity Safety practices: Electric shock prevention and first aid; personal protective equipment (PPE); electrical safety devices and workplace management; fire extinguisher types and usage Standards and Regulations Codes and standards: Overview of international and regional electrical standards (AS/NZS, NECA etc) Definitions and classifications: Electrical terminology, appliance classifications and plug/socket types Global standards: International voltages, frequencies and connector types Electrical Fundamentals Electricity generation: Methods of generating electricity Electrical systems: Single-phase and three-phase systems Basic concepts: Current, voltage, resistance, and electrical symbols Tools and testing: Common electrician's tools and multimeters Electrical laws: Ohm's Law, Kirchhoff's Laws and other fundamental principles Calculations and Formulas Electrical formulas: Equations for calculating power, voltage, current, resistance, impedance, reactance and other electrical parameters Motor calculations: Formulas for motor performance, power and speed Conversion factors: Unit conversions and reference data Electrical Components and Circuits Passive components: Resistors, inductors, capacitors and their characteristics Circuits: Series, parallel and combination circuits involving reactance Conductors and cables: Types, standards, selection and installation Wiring and Installations Wiring components: Plugs, sockets, switches and wiring diagrams Industrial applications: Industrial plug/socket configurations and switchgear Electrical plans: Symbols and layout Protection: Grounding, fuses and surge protection Lighting: Light bulb types, bases and LED technology Conduits, Fittings, and Bending Conduit systems: Types, materials and installation Conduit bending: Techniques and tools Emerging Technologies LED lighting: Characteristics, applications and precautions Fiber optics: Basics, termination and splicing Data cabling: RJ-45 wiring Electrical Equipment Transformers: Types, enclosures and voltage ratings Motors: Types, protection and connection diagrams Note: This summary provides a general overview of the publication's content. Specific details and depth of coverage may vary. More reasons why people love the Fasteners, Engineers and Electrical Black Books Their pocket-sized format allows you to carry them around. Their lay-flat binding and grease-proof pages make them practical for workshop environments. Their durable construction make it a practical tool for on-the-go and on-the-job reference. AIMS’ Note on Buying Industrial Supplies Breadth and depth of brands and categories: Go with a supplier that offers a wide range of reputable brands across multiple categories and sub-categories. Bulk purchase discounts: For large orders, check if you can take advantage of volume leverage. Some suppliers offer business accounts* that give you access to special pricing (volume discounts), preferential support and even credit eligibility (subject to supplier approval, terms and conditions). Product and service information: Evaluate the completeness and usefulness of data in their online product listings. Prudent suppliers will include as much useful information as possible to help you assess and compare products. In terms of service info, the supplier’s FAQs (if any) will give you a good idea of their standard policies*, processes and commitments. Promotions: Check for ongoing promotional campaigns so you can get the best prices. Many suppliers run regular discount-based promos. Some can point you to government-hosted rebate programmes like the SafeWork NSW $1000 Small Business Rebate. Safety compliance: Make sure the product in question meets Australian safety standards and regulations, especially if there are relevant compliance requirements or work health and safety (WHS) laws that apply to your business or state. Look for relevant certifications and markings where necessary. Supplier reliability: Choose reputable suppliers with a proven track record of delivering quality products and reliable customer service. Warranty and support: Check warranty terms and after-sales support* options, as this can be crucial in case of product defects or performance issues. Lead time and availability: Confirm product availability and estimated delivery times to avoid delays in your projects. Returns: Familiarise yourself with the suppliers returns and exchange policy in case you receive incorrect or damaged items. Delivery: Clarify delivery terms, including estimated delivery times, shipping costs and who handles insurance during transit (where applicable). *Need help with a purchase decision? Contact us directly via chat or send an email to sales@aimsindustrial.com.au. This blog's sub-topics People Also Ask — Engineer's Reference Black Books Q: What is the Engineer's Black Book? The Engineer's Black Book is a compact pocket reference guide widely used in machining, fabrication and maintenance workshops. It contains essential tables and data including drill and tap sizes, thread forms, cutting speeds, material hardness conversions, tolerances, surface finish grades and other workshop reference data compiled in a convenient field format. Q: Who should use an engineer's reference book on the job? Engineer's reference books are valuable for machinists, toolmakers, fitters, maintenance technicians and engineering apprentices who need quick access to standard reference data without consulting full engineering handbooks. They are particularly useful when selecting tap drill sizes, verifying thread standards, converting between metric and imperial measurements, or checking material properties at the machine. Q: What is the Electrical Engineer's Black Book? The Electrical Engineer's Black Book is a companion reference focused on electrical installation data, covering cable sizing, current ratings, conduit fill, voltage drop calculations, protection device ratings, Australian wiring rule references and other data relevant to electrical trades and engineering. Q: Are there Australian-specific editions of these reference books? Yes, Australian editions of engineering reference books are published to include Australian and New Zealand standards, metric SI units, and locally relevant data such as wiring rules references in the electrical edition. Using an Australian edition ensures the data aligns with local codes and the predominant metric measurement system used in Australian industry.
Read more
Choosing Between High-Speed Steel and Carbide Tools
(Taken from this post by Sutton Tools. Republished with permission. Edited for point of view, recency and relevance.) You may be wondering: “Should I use high-speed steel or carbide for my solid rotary tools, like endmills, drills and taps?” There’s no quick answer, because there are a lot of factors involved: Tool size Depth of cutting Required material removal rate Tool life Cycle time Cost Each type of component also presents different challenges, including design, size, batch quantity, material type and hardness. Sutton Tools General Manager, Jeff Boyd, discusses both to help us understand when to use which one. In this article, we discuss: Characteristics of HSS vs carbide HSS vs carbide for drilling HSS vs carbide for tapping HSS vs carbide for milling HSS powder metallurgy (HSS-PM) HSS versus carbide: General characteristics In general, the main characteristic of all high-speed steels is a high working hardness with excellent toughness. HSS tools also cost less than carbide tools and are often a good solution in ‘high-mix, low-volume’ applications. Carbide is much harder, so it has a longer tool life and faster cutting data than conventional HSS. The downside of that hardness is brittleness, so the cutting edge on carbide tools can quickly fracture or chip in certain situations. HSS can really excel over carbide due to its toughness in applications such as where: • The component to be machined is poorly clamped• Set-up is not rigid• The tool is a long-reach type with excessive overhang from the tool holder• Poor machine-spindle condition Let’s look at three common machining operations – drilling, tapping and milling – to gain a better understanding of when to use HSS or carbide tools. Drilling Carbide drills are generally used for high-volume hole production, where the higher tool cost can be justified on a cost-per-part basis. For deep high-volume holes, they are often available with internal coolant ducts, resulting in longer tool life and stable production. Use of through-the-spindle and high-pressure coolant offers excellent chip evacuation, particularly in deeper holes (>3xD), and is the most effective method for cooling the edge in cut. Carbide drilling is also the fastest way to produce holes in a wide range of metals, due to the higher cutting speeds and feeds possible. However, it’s important to know that in some higher Ni-Cr alloy steels (such as stainless steels), although the hole can be produced with high speeds, the condition of the walls of the hole can quickly work-harden. This can lead to other issues in the machining process, particularly if the hole is to be internally threaded; the tool life of the tap will be considerably shortened since it will be trying to cut through a hardened skin or surface. Importantly, carbide tools can be justified in low-volume production for their higher hardness because they enable harder materials to be machined, potentially up to 70+HRC. HSS drills have a very wide range of uses – from handheld applications to CNC machining in short batch runs – due to their toughness and lower cost. They are ideal for less rigid applications such as hand-held drilling, stack drilling and deep hole drilling where an internal coolant supply is not available. There are various geometries available for specific material grades to really cut through the material and leave it in its best annealed condition. Ideal for pre-tap drilling in stainless steel, HSS drills can really benefit the life of the tap when the right geometry is used to produce the hole! Tapping HSS tools are typically the first choice for tapping. They are by far the most common for internal thread production, with many HSS-PM versions available more recently for the various CNC machine tapping applications, different thread types and materials groups. Given their toughness, HSS tapping tools are also common in the Maintenance-Repair and Operations (MRO) industries, with hand taps or straight flute taps the most widely used. HSS taps are even used in large volume applications. In difficult-to-machine material applications, HSS-PM taps are still the first choice due to the process stability they offer. Carbide taps are not as popular due to the brittleness of carbide. It tends to chip in most tapping applications, particularly in blind holes. Carbide will fracture in steel applications at full depth, when the tap reverses and breaks the chips that were produced from the down cut in order to back out of the hole. As mentioned earlier, HSS has superior toughness over carbide, and in the tapping process this is very important. Due to the nature of tapping being a ‘slow speed, high feed’ type process, and with the spindle slowing-then reversing at the full thread depth and breaking the chip produced from the down stroke of the machine, it’s this action that the HSS toughness characteristic performs superior to carbide. That said, carbide taps can be used for some specific applications, including: • Tapping hardened steel, with a specific geometry that has negative cutting angles• Tapping high-silicon aluminium (AlSi), as the silicon content makes the material quite abrasive and carbide offers the best resistance• Some through-hole tapping applications in steel are possible, but only with specifically suitable geometry Carbide forming taps can also be justified in high-volume applications. Since there are no cutting edges, you can achieve long tool life without the possibility of chipping and thus justify the higher tool cost. They are quite popular in ADC12 (AlSi 8-12%) automotive aluminium applications. Milling Carbide endmills are by far the most popular because they offer the best Metal Removal Rates (MRR). Solid carbide endmills have become the first choice, given the variable helix designs combined with CAM packages that provide tool paths to suppress chatter from the natural vibration produced in a milling cut. Milling strategies such as trochoidal methods are now quite common. HSS endmills still have a place, such as for manual milling machines, smaller volumes, less rigid set-ups, and the like. HSS-PM: Best of both worlds? As noted, conventional grades of HSS have lower cutting speeds applied, but in recent times, HSS-PM (Powder Metallurgy) has been developed to bridge the gap between HSS and carbide tools. Simply put, HSS-PM is produced from a powder similar to carbide. This produces a finer grain structure which allows PM tools to reach a higher hardness than HSS, whilst still maintaining their excellent toughness. This means you can have a tool that will last longer than standard HSS and which can be used with high hardness materials, thereby closing the gap between the HSS and carbide tooling. There are also some needs in rough milling applications for HSS-PM due to the heavy style of cuts taken per pass. For example, when an aerospace component has a long cycle time, producers like to run their machines ‘lights-out’ overnight to do a lot of the roughing operations. They are not, however, confident to run with carbide endmills due to their brittleness, and this is where HSS-PM roughing endmills perform best. Whatever your application and operational considerations, it all comes down to finding the right solution. Shop for Sutton HSS and carbide tools now. AIMS' Note on Safe Use of Power Tools Inspection: Before using any tool, carefully inspect it for cracks, chips, loose handles, worn / mushroomed heads or any other signs of damage. Damaged or defective tools may cause harm! Ensure all guards are in place. Right tool for the job: Make sure you understand the intended purpose of each tool and choose the correct one for your specific job. Don't try to make a screwdriver work as a pry bar or a wrench as a hammer. Safe handling: Carry sharp tools pointed down and away from your body. Never carry tools in your pockets where they can cause injury. When passing a tool to someone, extend the handle first. PPE: Wear safety glasses or goggles to protect your eyes from flying debris. Consider gloves depending on the tool and task to prevent cuts or blisters but without compromising comfort, dexterity and protection. If working with noisy tools, wear ear protection. Maintenance: Keep your tools clean, sharp and properly maintained. Store them in a safe and organised place when not in use. During use: Maintain a firm grip and good balance while using the tool. Avoid distractions and focus on the task. Don't force the tool; let it work at its own pace. Keep cords clear of the cutting path and away from heat or sharp objects. Never leave a running tool unattended. When finished, turn the tool off, unplug it, and wait for any moving parts to stop completely before cleaning or making adjustments. This blog's sub-topics Our Tap Types guide covers every cutting and forming tap variant with material-specific selection rules. People Also Ask — HSS vs Carbide Cutting Tools Q: When should I choose HSS over carbide cutting tools? High-speed steel (HSS) is the better choice when: (1) using a hand drill, portable drill press, or any setup with significant runout or vibration — carbide is brittle and will chip under these conditions; (2) machining interrupted cuts such as keyways, splines, or cross-holes — HSS handles intermittent impact better than carbide; (3) the workpiece material is tough or stringy (e.g., copper alloys, some stainless grades) where HSS's toughness prevents chipping; (4) tooling cost per use matters more than tool life — HSS drills, taps, and endmills are significantly cheaper than carbide equivalents. Q: What is the speed advantage of carbide over HSS? Solid carbide tooling can typically run at 3–5× the cutting speed (Vc) of equivalent HSS tools in the same material. In mild steel (e.g., 250 MPa), an HSS endmill might run at 25–35 m/min while a carbide equivalent runs at 80–120 m/min. In aluminium, HSS runs at 60–90 m/min while carbide can exceed 300 m/min. This speed advantage translates directly to shorter cycle times and higher production output. The caveat is that realising carbide's speed potential requires a rigid machine tool with minimal vibration and accurate coolant delivery. Q: Can I use carbide drill bits in a hand drill? Solid carbide drill bits are generally not recommended for hand drills. Carbide is extremely hard but brittle — it is highly sensitive to the bending and shock loads that occur with the slight flex and misalignment inherent in hand drilling. A carbide drill subjected to lateral force during entry will chip or snap. Carbide-tipped masonry drills are designed for percussion drilling and are an exception. For hand drilling in steel, cobalt HSS (HSS-Co) is the better choice — nearly as hard as carbide in terms of heat resistance but much more tolerant of the conditions a hand drill creates. Q: Does HSS-Co 8% outperform HSS-Co 5% for stainless steel? HSS-Co 8% (M42 grade) offers higher hot hardness than HSS-Co 5% (M35 grade), making it more resistant to the heat generated when machining work-hardening materials like 304 and 316 stainless steel. In demanding stainless applications — deep holes, heavy feeds, or interrupted cuts — HSS-Co 8% will hold its edge longer and run at slightly higher speeds than HSS-Co 5%. However, HSS-Co 8% is also more brittle and more expensive. For most stainless steel drilling in fabrication workshops, HSS-Co 5% (such as Sutton Tools' Blue Bullet cobalt series) provides an excellent cost-performance balance. Q: What does TiAlN coating do for carbide and HSS tools? Titanium Aluminium Nitride (TiAlN) coating significantly increases the surface hardness and oxidation resistance of both carbide and HSS tools. It performs best in dry machining or high-speed machining with minimal coolant because TiAlN forms a hard aluminium oxide layer at high temperatures that acts as a thermal barrier, protecting the cutting edge. TiAlN is particularly effective on carbide endmills in steels, cast iron, and titanium alloys. Important caveat: TiAlN reacts chemically with aluminium workpieces — use an uncoated or TiN-coated tool for aluminium to prevent built-up edge and tool damage. Need key steel? Browse the AIMS range at key steel.
Read more
Clamping Made Easier and Faster with Lockjaw
(Taken from this post by Sutton Tools. Republished with permission. Edited for point of view, recency and relevance.) Over many years, Lockjaw pliers and clamps have gained a devoted following of tradespeople, weekend warriors and hobbyists. Quite simply, they are known to be much easier and more reliable to use than other brands. The key is the ability for users to set a pressure – from slight to extreme – via the unique Set and Forget™ adjustor. The plier or clamp will then hold this same pressure automatically, self-adjusting to grip the correct distance according to the thickness of the material. This feature is extremely useful when clamping different materials. For example, pine wood could be damaged at the pressure you’d use to hold a slab of Masonite, and Masonite could drop from the clamp at the pressure you’d use for a softwood. So, you want to set the pressure to suit the material, regardless of its thickness. Most importantly, the process of setting the pressure is by turning a screw mechanism embedded in the tool’s handle; so it’s a single-handed operation. This capability is critical for clamping, because you typically need the other hand to manipulate the material you are holding. Hence, the Lockjaw promise: 7x faster, 100% easier. In manufacturing, construction and similar industries involving regular clamping of materials, this time-saving ability can translate to thousands of dollars a year in process time savings. More stocks now available As a tool manufacturer and supplier, Sutton Tools is proud to be the official Australian distributor of Lockjaw products and has a reputation for maintaining ready-to-ship stocks of over 16,000 SKUs at adequate levels for their customers’ needs. However, due to the popularity of Lockjaw pliers and clamps, they have not always been able to prevent shortages and backorders. To address this, they have recently reorganised and streamlined their Lockjaw supply chain processes, which means stock availability should no longer be an issue. They’ve also improved the packaging, so it’s less likely to suffer damage in transit. Shop for Lockjaw pliers and clamps now. AIMS' Note on Safe Use of Hand Tools Inspection: Before using any tool, carefully inspect it for cracks, chips, loose handles, worn / mushroomed heads or any other signs of damage. Damaged or defective tools may cause harm! Ensure all guards are in place. Right tool for the job: Make sure you understand the intended purpose of each tool and choose the correct one for your specific job. Don't try to make a screwdriver work as a pry bar or a wrench as a hammer. Safe handling: Carry sharp tools pointed down and away from your body. Never carry tools in your pockets where they can cause injury. When passing a tool to someone, extend the handle first. PPE: Wear safety glasses or goggles to protect your eyes from flying debris. Consider gloves depending on the tool and task to prevent cuts or blisters but without compromising comfort, dexterity and protection. If working with noisy tools, wear ear protection. Maintenance: Keep your tools clean, sharp and properly maintained. Store them in a safe and organised place when not in use. People Also Ask — Locking Pliers & Clamps Q: What are locking pliers used for? Locking pliers — sometimes called by the trade as a self-grip or mole-type tool — clamp onto a workpiece and stay locked with strong, hands-free pressure until released. That makes them a cross between pliers and a clamp. Tradespeople use them to grip and turn rounded or damaged fasteners, hold parts together for welding or drilling, act as a temporary handle or clamp, and free seized nuts and bolts. Because the jaws lock under adjustable pressure, you can set them onto an item and let go, freeing both hands for other work. Their versatility is why they are a staple in automotive, fabrication and general maintenance kits. Q: How do you adjust and lock the pliers onto a workpiece? Locking pliers have an adjusting screw in the end of one handle that sets the jaw opening and clamping force. You turn the screw so the jaws are slightly smaller than the item, then squeeze the handles until they snap shut and lock with firm pressure. If they are too loose or too tight, you release and fine-tune the screw and try again. A release lever in the handle pops them open when you are done. The knack is setting the screw so the lock engages with a positive snap and real clamping force — too loose and they slip, too tight and they will not close. Q: What is the difference between locking pliers and a clamp? A standard clamp is purpose-built to hold work together with a fixed frame and a screw or lever, giving steady, distributed pressure for tasks like glue-ups and welding fit-up. Locking pliers are a portable, hand-sized tool that locks onto a point with concentrated jaw pressure, doubling as a gripping and turning tool as well as a temporary clamp. Locking clamps blend the two — locking-plier mechanisms fitted with clamp-style jaws (such as C-clamp or sheet-metal jaws) for holding fabrication work. Choose a clamp for steady holding over a wider area, and locking pliers where you need a quick, strong, portable grip or a turning tool. Q: What jaw shapes are available on locking pliers? Locking pliers come with several jaw styles for different jobs. Curved jaws are the general-purpose shape and grip round and hex items well. Straight or long-nose jaws reach into tight spots and grip small parts. Wide or sheet-metal jaws spread the clamping force to hold panels flat without marking, which suits fabrication. C-clamp jaws turn the tool into a deep-reach welding clamp. Chain and specialty versions grip large or awkward shapes. Matching the jaw shape to the task — gripping, turning, or clamping flat work — gets the best hold, so many workshops keep a few jaw styles on hand. Q: Can locking pliers damage the workpiece? They can, because they grip with concentrated, serrated jaw pressure that can mar soft surfaces, crush thin material or chew up the corners of a fastener if over-tightened. That is a fair trade-off when freeing a seized or already-damaged bolt, but on finished or soft parts it is worth protecting the surface — backing the jaws with cloth or soft pads, using smooth or wide jaws, or choosing a proper clamp instead. Set the clamping screw only as tight as the job needs rather than maximum. Used with that bit of judgement, locking pliers grip securely without leaving unnecessary damage. Need adjustable hand reamers? Browse the AIMS range at adjustable hand reamers.
Read more
Stripped Threads: Repair Options & Prevention Guide
Stripped threads are recoverable in most cases. The trick is reading the damage correctly before reaching for the drill — pick the wrong repair and you turn a fixable hole into a bin job. This guide walks through how to diagnose stripped threads, the full repair ladder from cheapest to most permanent, and the prevention habits that stop them happening again. For the step-by-step installation of Helicoil, Recoil, TimeSert and Keysert inserts, see our dedicated Stripped Thread Repair Guide. Quick Reference — Stripped Thread Repair Options Damage Severity Recommended Repair Cost Tier Skill Level Holds Original Bolt Size? Minor scoring, threads mostly intact Re-tap same size (chase the thread) $ Beginner Yes One or two stripped threads, geometry allows Tap oversize, use larger bolt $ Beginner No Stripped female thread in alloy/aluminium Helicoil or Recoil wire insert $$ Intermediate Yes High-load or repeated assembly TimeSert solid bushing $$$ Intermediate Yes Soft parent, anti-rotation needed Keensert / key-locking insert $$$ Intermediate Yes Spark plug thread in alloy head Spark plug-specific TimeSert or Helicoil kit $$$ Intermediate Yes Complete bore failure, no thread material left Weld up, re-drill, re-tap $$$$ Advanced Yes (if done well) Critical safety component, repeat failure Replace the part Varies — — Pick from the top down — start with the simplest repair the damage allows. Jumping straight to a Helicoil when a tap chase would do is wasted time and money. Why Threads Strip in the First Place Threads don't strip for no reason. Understanding the cause matters because if you repair the symptom without fixing the cause, you'll strip the new threads too. Over-torque — The most common cause. "Tight enough" by feel is unreliable. Aluminium and brass have a fraction of the tensile strength of steel; what feels firm in your wrist can be 30% past yield. Always torque to the manufacturer's spec with a calibrated wrench. Cross-threading on assembly — Starting a bolt at the wrong angle cuts new threads at the wrong pitch. Common when blind-feeding bolts overhead or into recesses. Once cross-threaded, the original threads are compromised regardless of how tight you get it. Mismatched fasteners — Metric bolt into imperial hole, or M10×1.25 into an M10×1.5 hole. The first turn or two will bite, then the threads tear. See our Threading Tap Metric & Imperial Size Chart if you're unsure about pitch. Soft parent material — Aluminium, magnesium alloy, plastic and brass all strip more easily than steel. Engine blocks, alloy castings and gearbox housings are common victims. Corrosion welding the bolt — Steel bolt in alloy or stainless host. Galvanic corrosion bonds the bolt to the hole. When you try to undo it, the bolt brings the female threads with it. For removal techniques first, see How to Deal with Stuck Bolts and Nuts. Dirt and swarf in the threads — Grit jams between thread peaks, jacks the bolt up off-axis, then the bolt strips a path through whatever material gives first. Repeated assembly cycles — Manifolds, sumps and inspection covers that get removed every service. Each cycle wears the female thread a little. Aluminium suffers the most. Impact drivers on soft material — Cordless impact wrenches in tradies' hands are torque monsters. Pulling a wheel nut down with one is fine; running a sump plug in with one will strip the alloy pan first time. Female vs Male Thread Stripping Knowing which side has failed changes the repair completely. Female (internal) thread stripped Most common scenario. The bolt comes out clean, the host material has the stripped threads. Telltale signs: Bolt threads in the relevant section look intact, possibly with a smear of aluminium or alloy stuck on them Bolt spins freely or feels "soft" when torqued You can see torn or smeared metal in the threaded hole The bolt may sit lower than before, or pull out under load This is the case the rest of the guide focuses on. All the repair options below — re-tap, oversize, Helicoil, TimeSert, Keensert — restore female threads. Male (external) thread stripped Less common but does happen, particularly with grade-5 bolts going into high-grade nuts, or older / worn bolts being re-used. Telltale signs: The female threads still look crisp inside the nut or hole The bolt threads in the relevant section look smeared, snapped or shortened The bolt feels rough through its travel Repair is simpler: replace the bolt. Match the original grade (8.8, 10.9, 12.9 — see our Bolt Grade Chart) and length. Don't downgrade — if a 10.9 bolt was specified, fit a 10.9, not an 8.8. Repair Option 1: Re-Tap Same Size (Thread Chasing) Cheapest and quickest repair. Suitable when: Threads have minor scoring or surface damage Most of the thread depth is intact The bolt still starts in the hole and gets at least a few turns in before binding The hole is in steel or cast iron (alloy/aluminium usually needs more) You're not cutting new threads — you're cleaning up the existing ones. Use a tap of the same size and pitch as the original thread, run by hand with a tap wrench. A thread file or thread chaser tool can also do the job for external bolt threads. Critical details: Use cutting fluid (Tap Magic or similar) — even on a clean-up pass Quarter turn forward, half turn back to clear swarf — same as cutting fresh threads Use a taper, plug or bottoming tap based on hole depth. Blind hole = bottoming tap for final pass. See our Tap Types Explained for help picking the right one If the tap binds hard halfway in, stop. The threads are too damaged for a re-tap; move to Option 2 or 3 Reassemble with new fasteners and torque to spec. If the bolt still feels soft when torqued, the threads were beyond chasing — escalate the repair. Repair Option 2: Tap Oversize to a Larger Bolt One step up. Drill the hole bigger, tap a new larger thread, fit a bigger bolt. Suitable when: The original threads are too damaged to chase Hole geometry allows a larger bolt — i.e. there's enough material around the hole that going up one size won't break through into a water jacket, oil gallery or the next bolt hole The mating part also has clearance for a larger bolt head and shank — or you can drill the mating clearance hole The application can tolerate non-original spec Typical step-ups: M6 → M8, M8 → M10, M10 → M12, ¼" → 5/16", 5/16" → 3/8". You'll need a drill bit matched to the new tap (refer to the tap drill chart), the new tap, and the new bolts. Watch-out: on critical applications — engine internals, suspension, lifting points — don't oversize without checking the engineering. The joint was designed for a particular bolt size to handle particular loads. Going bigger isn't always "stronger" if the bolt now bottoms in the hole or the mating component can't take it. Repair Option 3: Helicoil / Recoil Wire Thread Insert The workshop favourite for restoring original-size threads. A coiled stainless wire insert fits into an oversized tapped hole and presents the original thread spec to the bolt. Suitable when: You need to keep the original bolt size — common for spec components The parent material is soft (aluminium, alloy castings) and a re-tap won't hold The repair needs to handle service torque without further wear You want a repair that's stronger than the original female thread in soft material How it works (in summary — full step-by-step is in the Stripped Thread Repair Guide): Drill the damaged hole out to a Helicoil-specified oversize Tap with a Helicoil-specific tap (slightly different geometry to a standard tap) Wind the wire insert in using the supplied tang tool until it sits just below flush Snap off the installation tang with the break-off tool Brand notes: Helicoil — the original brand. Generally accepted as the benchmark; the name has become generic in workshops Recoil — Australian brand, widely available, generally accepted as equivalent quality. Same wire spec, same installation method Champion — sells thread repair kits aimed at the trade market. Good value for occasional use, kit usually includes drill, tap, tang tool and a range of insert lengths Browse our thread inserts range, or Champion thread repair kits for the all-in-one option. Helicoil and Recoil inserts use stainless steel wire of similar specification; treat as interchangeable for general workshop use. Specific aerospace or motorsport specs may call out one brand or the other — defer to the engineering drawing. If you are looking up an older Recoil part number from a 2007 or 2013 purchase order, our Recoil RC part number lookup maps every legacy code to the current 2023 RC kit number. Repair Option 4: TimeSert Solid Bushing Insert Step up from Helicoil. Instead of a coiled wire, TimeSert is a solid threaded bushing that's tapped into place and locked by a roller tool that expands the bottom of the insert into the parent material. Suitable when: The application is high-load or critical — cylinder heads, engine main caps, high-cycle fastenings A Helicoil has already been tried and pulled out The insert must positively lock against rotation under repeated assembly You need maximum strength in soft parent material The installation is more involved — drill, counterbore, tap, install with the supplied driver, then lock with a roller tool. Each TimeSert kit is dedicated to one thread size, so you buy by application (e.g. an M11 head bolt kit for a specific engine). Why workshops choose TimeSert over Helicoil: Solid wall — won't unspool or cross-thread on installation Locks mechanically into the parent — won't pull out Better for through-loading where the bolt may be cycled hundreds of times Standard choice for head bolt repairs in alloy engine blocks TimeSert is typically the recommended repair for stripped head bolt threads on modern alloy blocks. Brand-specific kits exist for common applications (e.g. Subaru head bolts, Audi head bolts). Confirm the correct kit for the engine before ordering. Repair Option 5: Keensert / Key-Locking Insert Designed for applications where the insert itself must not rotate in the parent material under repeated bolt assembly. After the insert is screwed in, small steel keys are driven down through pre-cut slots in the insert and into the parent material — mechanically locking the insert against rotation. Suitable when: The parent material is soft and a wire insert might back out over time The bolt will be assembled and disassembled many times in service (inspection covers, removable panels) Vibration is severe (military, mining haul truck, agricultural) The application is critical enough that "almost certainly won't rotate" isn't good enough Keenserts are more expensive per insert than Helicoils and add the installation step of driving the keys. For one-off repairs, Helicoil or TimeSert usually wins on cost and time. For production repair lines or known repeat-strip applications, Keensert is worth the spend. Repair Option 6: Weld Up, Re-Drill, Re-Tap Last resort before binning the component. Suitable when: The bore is completely destroyed — no thread material left, possibly oversized and damaged Inserts can't be used because the parent material is too thin or compromised The component is irreplaceable, expensive, or being restored The job: Drill out the existing hole to clean parent material Weld the hole closed (TIG is the cleanest choice on alloy or stainless) Allow to cool, dress the welded area flush Centre-punch and re-drill the new hole to the correct tap size Tap the new thread Watch-outs: Welding distorts surrounding material — check flatness on critical surfaces afterwards Welding alloy and aluminium changes the heat treatment locally — strength can drop near the weld If the component is a casting, weld porosity is a risk — pre-heat helps This is a machine-shop job for most workshops. Quote it out before committing. Spark Plug Thread Repair Worth a dedicated section because it's one of the most common stripped-thread repairs in Australia, and it has its own specialist kits. Why spark plug threads strip so often: Aluminium head, steel plug — soft female thread, hard male thread Plugs over-torqued by feel — anti-seize on the threads further confuses the feel Heat cycling between cold start and operating temperature wears the threads each cycle Plugs left in too long and seizing — then forced out, taking the threads with them The fix is usually a spark plug-specific Helicoil, Recoil or TimeSert kit. These kits are sized for the standard plug threads (M14×1.25, M12×1.25, 14mm taper-seat etc.) and include all the tools for an in-situ repair — most importantly, drill stops and tap collars to prevent metal swarf falling into the cylinder. A few practical points: Wind off-the-shelf wheel-bearing grease onto the drill flutes and tap to catch swarf Rotate the engine so the affected cylinder is BDC before drilling Vacuum or compressed-air the cylinder out before fitting the new plug Use the correct torque on the new plug — Denso/NGK spec 20-25 Nm for M14 gasket, 20-30 Nm for M14 taper seat, 15-20 Nm for M12. Don't rely on feel. Spark plug torque values vary by manufacturer, plug type (taper vs gasket seat) and thread size. Always confirm against the vehicle service manual or plug manufacturer specification. Material-Specific Notes Aluminium and alloy castings The most common stripped-thread material. Aluminium has roughly one-third the tensile strength of mild steel. Key points: Always torque to spec — never to feel. The yield point is much lower than steel Use anti-seize sparingly. Lubricated threads transmit more clamp force at the same torque — over-torque is easy. Reduce torque setting by 15–25% when using anti-seize (check your service manual) If a thread strips once in aluminium, fit an insert — chasing it back to spec will strip again within a few cycles For repeat-removal threads (sumps, manifolds), a Helicoil or TimeSert often outlasts the original aluminium thread Cast iron Tougher than aluminium but brittle. The thread cuts cleanly when fresh but can chip if shock-loaded. Cast iron threads handle re-tapping well; oversize works too. Watch for hidden porosity if you're welding for Option 6. Mild and medium-carbon steel The most forgiving substrate. Threads are tough, hold well, and respond well to chasing or re-tapping. If you've stripped a steel thread, the cause was usually over-torque or the wrong size bolt — not the steel. Stainless steel — galling risk Stainless-on-stainless threads can gall (cold-weld) during assembly, which presents like a stripped thread but is actually thread material being torn off and welded to the bolt. Prevention: anti-seize designed for stainless (nickel or copper-based), slow assembly speed, no impact tools. If galling has happened, the bolt usually has to be cut off, and the female thread often needs an insert to recover. Brass and bronze Soft, easily damaged. Common in plumbing and electrical hardware. Re-tap to original size if there's any meat left; otherwise step up or insert. Don't over-torque brass fittings — sealant or PTFE tape does most of the sealing work, not bolt tension. Preventing Recurrence A stripped thread is a symptom. The first time, you fix the symptom. After the repair, fix the cause. Torque to spec, every time — Use a calibrated torque wrench, not feel. The cost of a decent wrench is a fraction of the cost of one stripped thread on an alloy component Start every bolt by hand — At least two full turns by hand before any power tool. If it doesn't turn freely by hand, stop and find out why Clean threads before reassembly — Wire brush, compressed air, or a thread chaser. Dirt and swarf in the threads guarantee an off-axis start Anti-seize on threads that see corrosion or heat cycling — But adjust torque accordingly (see aluminium note above) Threadlocker on threads that vibrate loose — Loctite 243 for general medium-strength applications; pick from our Loctite range for high-strength or high-temp use Replace fasteners on critical assemblies — Head bolts, conrod bolts, suspension bolts: many manufacturers spec one-time-use stretch bolts. Don't re-use them, regardless of how good they look Don't impact-drive into soft material — Use a torque wrench or a hand spanner for sumps, manifolds and inspection covers in alloy or aluminium Check thread engagement length — The rule of thumb is at least 1× bolt diameter of engagement in steel, 1.5× in aluminium, 2× in plastic. Short engagement makes any minor over-torque a strip When to DIY vs Send Out to a Machine Shop Scenario DIY-friendly Machine shop Standard re-tap on workshop steel Yes — Step-up oversize in alloy Yes — Helicoil / Recoil into accessible hole Yes — TimeSert in non-critical area Maybe — Head bolt threads in alloy block — Yes — head off, line-bored, TimeSert installed Spark plug repair in-situ Yes — with the right kit — Welded repair on a casting — Yes — TIG and machining capability Critical lifting or structural component — Yes — and engineering sign-off AIMS' Note on Stripped Thread Repair AIMS supplies the consumables for stripped thread repair across the trade and industrial market: Thread inserts — Helicoil-compatible and equivalent wire inserts in common sizes Champion thread repair kits — drill, tap, tang tool and inserts in one box, sized for popular bolt sizes Taps — for chasing existing threads or cutting fresh oversize threads. Sutton Tools and Bordo for AU-made quality Cobalt drill bits — for drilling out broken bolts before tapping, and for harder materials Loctite threadlockers — to keep the repair from happening again Fasteners — replacement bolts in correct grade and length For the step-by-step installation procedures on Helicoil, Recoil, TimeSert and Keysert inserts, our Stripped Thread Repair Guide covers each system in detail with brand-specific notes. If you're not sure which repair option suits your application — or which kit covers the bolt size you need — ring us on (02) 9773 0122 or use the contact form. We'll point you at the right kit, or refer you to a local machine shop if the job's beyond a DIY repair. Frequently Asked Questions Can I just use a bigger bolt instead of doing a thread repair? Sometimes, yes — Option 2 in this guide. Step up one size (M8 → M10, ¼" → 5/16") if the hole geometry allows and the mating part can take it. The watch-out is critical applications where the original bolt size was engineered for a specific load. Don't oversize on safety-critical joints without checking the spec. Is a Helicoil as strong as the original thread? In aluminium or alloy parent material, a Helicoil insert is typically stronger than the original female thread. The wire insert spreads load across more thread engagement and presents a steel surface to the steel bolt. In steel parent material, a Helicoil is comparable to original — neither stronger nor weaker for most applications. What's the difference between Helicoil and Recoil? Practically, very little for general workshop use. Both are stainless wire thread inserts of similar specification. Helicoil is the US original and the name is often used generically. Recoil is an Australian brand, widely available locally, with similar quality. Specific aerospace or motorsport specs may call out one or the other — defer to the engineering drawing. When should I choose TimeSert over Helicoil? TimeSert is the better choice for high-load, high-cycle, or critical applications — cylinder heads, engine main caps, repeated-removal assemblies. The solid bushing won't unspool, locks mechanically into the parent, and is the standard repair for stripped head bolt threads in alloy engine blocks. Can I repair a stripped spark plug thread with the engine in the car? Yes — that's exactly what spark-plug-specific Helicoil and TimeSert kits are designed for. The kit includes drill stops and tap collars to prevent swarf falling into the cylinder. Rotate the engine to BDC on the affected cylinder, pack drill flutes with grease to catch chips, and vacuum the cylinder out before fitting the new plug. Why did my thread strip the first time I tightened it? Most likely causes: cross-threaded start (bolt entered at an angle), wrong bolt size (metric into imperial or wrong pitch), over-torque, or dirt in the threads. Stripping a fresh thread on the first assembly almost always means one of these — the threads themselves were fine. Do I need a special tap for a Helicoil repair? Yes. Helicoil and Recoil taps have slightly different geometry to a standard tap — they cut a thread profile that accepts the wire insert. Don't try to use a standard tap; the wire won't seat correctly. The taps are supplied in repair kits and also sold separately. What's the maximum number of times I can re-use a thread before it strips? There's no fixed number — it depends on parent material, torque each cycle, and how clean the assembly is. As a rough guide: steel threads will outlast most components. Aluminium threads in sump plugs, manifold studs and rocker covers typically last 3–10 service cycles before needing attention. If you're removing the same fastener regularly, fit an insert proactively. Can I use thread locker (Loctite) on a Helicoil repair? Yes — use threadlocker on the bolt going into the insert the same way you would on any thread. Don't use threadlocker on the insert itself going into the parent material — the supplied Helicoil insert is designed to grip the parent thread on its own. The bolt comes out with metal stuck to its threads. What does that tell me? The female thread is stripped — the parent material has welded or smeared onto the bolt threads. This is typical when alloy or aluminium threads strip. Clean the bolt with a wire brush to confirm; if the bolt threads themselves are intact under the smear, the repair is on the female side. Is there a way to test if a thread is good without trying it under torque? A simple feel-test: a healthy thread should start with the bolt by hand, run smoothly through the full engagement length, and only get firm in the last quarter turn. If it spins easily for the full travel and never builds resistance, the female threads are gone. If it binds halfway in, the threads are damaged but possibly chaseable. My head bolt threads are stripped in an alloy engine block. What's the standard repair? TimeSert is the trade-standard repair. Brand-specific kits exist for common engines (Subaru, Audi, Holden, Ford). The job is normally done with the head off — drill, counterbore, tap, install with the driver, lock with the roller tool. Many workshops will quote this as a discrete job; for a one-off DIY, the kit is a meaningful investment. Confirm the correct kit by engine code before ordering — head bolt sizes vary even within manufacturer ranges. Why did my thread strip with a torque wrench set correctly? A few possibilities: torque wrench out of calibration (test annually); lubricant on threads (anti-seize, oil, threadlocker) reducing friction so the same torque transmits more clamp force; bolt grade lower than spec (an 8.8 substituted for a 10.9); or the female thread was already partially damaged before this cycle. Calibrate your wrench, check the lube state, and verify the bolt grade against spec. Can I install a Helicoil in a through-hole? Yes — through-holes are easier than blind holes because you can clear swarf easily. Use a standard taper tap (Helicoil pattern) for the drilling pass. The only difference is you need to make sure the insert is positioned within the hole — not protruding either side. Pick an insert length that suits the available depth. Will a stripped thread repair fail an engineering inspection or certification? For most workshop applications, no — a properly installed TimeSert or Helicoil is accepted as a permanent repair. For aerospace, defence, structural or lifting-equipment certifications, the repair often needs to follow a specific approved procedure (kit brand, install method, sign-off). Check the relevant standard or engineering drawing before committing to a repair on certified equipment. Where can I get a thread repair done if I don't want to DIY? Most general engineering shops and automotive machine shops handle thread repair work. Engine machine shops specialise in head bolt repairs and spark plug repairs in-situ. For mining or industrial gear, mobile fitters often carry kits and can do the job on-site. AIMS doesn't run a workshop, but we supply the kits — give us a ring on (02) 9773 0122 if you need a referral to a local shop. People Also Ask — Stripped Thread Repair Q: What are the main options for repairing a stripped thread? The article outlines six options in escalating order of complexity and cost: re-tap the same size (thread chasing for minor damage), tap oversize to accept a larger bolt, Helicoil or Recoil wire thread insert, TimeSert solid bushing insert, Keensert key-locking insert, and weld up/re-drill/re-tap as a last resort. Q: When is a Helicoil or Recoil wire thread insert the best repair option? Wire thread inserts are the preferred repair for stripped female threads in aluminium and alloy materials — they restore the original bolt size, are widely available in metric and UNF sizes, and produce a thread that is typically stronger than the original tapped hole in soft parent material. Q: What is the practical difference between a TimeSert and a Helicoil? A TimeSert is a solid threaded bushing that locks mechanically into the parent material — it is preferred for high-load applications and connections that are assembled and disassembled frequently. A Helicoil is a coiled wire insert that is lighter and faster to install; TimeSerts are considered more robust for critical joints. Q: Why do threads strip in the first place? The most common causes are over-torquing beyond the material's thread strength, cross-threading (starting the fastener at an angle to the hole), corrosion that weakens the thread engagement over time, using the wrong thread pitch or type, and repeated assembly cycles in soft parent materials such as aluminium. Q: What is thread chasing and when is it appropriate? Thread chasing runs a tap through an existing thread to clean up minor damage — straightening slightly bent threads, removing corrosion, and restoring thread profile. It is appropriate when the thread geometry is largely intact. If threads are stripped or broken, a fuller repair method is required. Looking for metric thread forming taps? Our metric thread forming taps range covers the common sizes and brands.
Read more