Knurling Guide: Patterns, Pitches & Lathe Technique

Cross-reference our Pulley Speed Ratio guide for the V₂ = V₁ × (D₁ ÷ D₂) formula and worked examples.

Knurling looks simple — press a patterned wheel into a spinning workpiece, get a textured grip. In practice it's the metalworking operation most likely to humble a confident machinist. Diameter wrong by a few thou and the pattern double-cuts. Pitch wrong for the diameter and you get an uneven pattern that won't clean up. Wheels not perpendicular and you walk the tool along the work. RPM too high and you fling oil everywhere while the pattern loads up.

This guide covers what knurling is, the standard patterns under DIN 82 and ANSI B94.6, the cut-vs-form question that decides which tool you need, pitch selection, the workpiece diameter rule that prevents the most common failure mode, RPM and feed, technique step-by-step, troubleshooting, and the Maxigear range stocked at AIMS for Australian workshops.

What is knurling and what is it used for

Knurling is the process of impressing or cutting a pattern of small ridges onto the cylindrical surface of a workpiece — usually on a lathe, occasionally with a hand tool. The pattern provides grip, decoration, or a controlled interference fit when the knurled part is pressed into a hole.

The five common applications:

• Hand grip — tool handles, screwdriver bodies, calliper thumbwheels, knobs, jig handles. The knurl gives a positive grip with oily fingers.
• Decorative finish — barbell sleeves (the Olympic standard barbell knurl), camera bodies, watch crowns, premium hand-tool aesthetic.
• Interference fit — knurled inserts pressed into plastic, soft metal, or wood. The raised pattern bites in and resists pull-out and rotation.
• Diameter increase for repair — old machinist trick — knurl a worn shaft to lift the diameter for a press fit, though it's a workshop bodge, not engineering practice.
• Surface area — increasing the contact area for adhesives or coatings.

Knurling patterns under DIN 82 and ANSI B94.6

The international standard for knurling patterns is DIN 82 (Germany, also ISO 13444). The American equivalent is ANSI B94.6. Both define the same five geometric patterns, with different naming conventions.

The DIN 82 pattern codes:

In Australian workshop language, you'll usually hear:

• Straight — same as DIN 82 RAA
• Diagonal — DIN 82 RBL or RBR (specify direction)
• Diamond — usually means RGE (raised diamond, the most common pattern)

The DIN 82 designation includes the pitch — for example RGE 0.8 is a raised diamond knurl at 0.8 mm pitch. Always specify both pattern and pitch when ordering wheels or describing a knurl on a drawing.

Pitch selection

Pitch is the distance from one ridge crest to the next, measured perpendicular to the ridge. Standard metric pitches under DIN 82 are 0.5, 0.6, 0.8, 1.0, 1.2, 1.5, 1.6, and 2.0 mm. Imperial designations are TPI (teeth per inch) — common values are 14, 21, 25, 33, and 40 TPI.

Pitch selection is dominated by two factors: workpiece diameter and application.

The general rule: smaller diameter, finer pitch. A 1.5 mm pitch on a 10 mm shaft will only get a few ridges around the circumference and look terrible. A 0.5 mm pitch on a 50 mm shaft will be slippery and visually inconsistent.

Cut knurling vs form knurling — the critical distinction

Knurling tools come in two fundamental types and they work in completely different ways.

Form knurling is what most workshops do. The wheel doesn't remove material — it cold-forms the pattern by pressing the workpiece between the wheel and the resistance from below. Plastic deformation, not cutting. The metal flows into the gaps between the wheel teeth, and the workpiece grows in diameter.

Cut knurling uses an angled wheel that cuts chips like a fly cutter, producing a pattern by removing material rather than displacing it. Cut knurlers are common in production environments and on hard materials where form knurling would either fail or break the workpiece.

Knurling tool types

The five common tool styles you'll encounter:

For most Australian small-shop work — knobs, handles, repair work, occasional decorative knurls — a scissor (clamp) knurler is the best balance of price, ease of use, and result quality. A self-adjusting knurler (Maxigear sells one) is a step up.

AIMS Maxigear knurling range

AIMS stocks the Maxigear range of knurling tools and wheels — the Australian-distributed line covering hobby through to general workshop applications.

For diamond knurling you need a matched pair — one left-hand and one right-hand wheel of the same pitch. Single straight wheels for straight pattern only. View the full range at our knurling tools and accessories collection, or call the team on (02) 9773 0122 if you're not sure which combination suits your job.

Calculating workpiece diameter for a clean pattern

This is the rule that prevents the most common knurling failure: the double-cut or fuzzy pattern that won't clean up no matter how many passes you make.

For a clean, single-trace knurl, the workpiece circumference must be a whole-number multiple of the pitch. If the wheel has 25 teeth and the workpiece circumference is exactly 25 × pitch (or 50 × pitch, or 75 × pitch), each tooth lands in the same impression every revolution and the pattern reinforces itself. If the circumference is, say, 25.4 × pitch, the wheel skips between two patterns each revolution and you get the dreaded double-cut.

The formula:

Worked example: form knurling at 1.0 mm pitch.

If you want a 20 mm finished diameter at 1.0 mm pitch, turn the workpiece to 19.10 mm before knurling. Form knurling will lift the diameter by approximately 0.7 × pitch (~0.7 mm here), bringing the finished diameter close to 19.8 mm. Adjust your starting diameter to land where you want.

RPM, feed and cutting fluid

Knurling is a slow operation. Too fast and the wheel rolls instead of forming, the pattern loads up with displaced metal, and the heat builds up to the point of work-hardening the surface. Standard practice:

The forum-validated rule: low RPM, fast feed. 30–100 RPM, 20–30 thou per revolution. Most knurling failures come from operators running lathe-turning RPM (300+) and crawling the carriage along — exactly backwards. The pattern needs the wheel to roll over the work without overheating and the carriage to advance fast enough that you cover the knurl in a few revolutions.

Cutting fluid is mandatory on steel and stainless. The fluid keeps the chips and displaced metal flushed off the wheel, prevents loading, and keeps the workpiece cool enough to avoid surface work-hardening. Skipping fluid is the second most common cause of pattern flaking after running too fast.

Knurling technique step-by-step

The standard form-knurling sequence:

1. Calculate and turn the diameter. Use the formula above for clean pattern indexing. Aim for a whole-number multiple of pitch.
2. Mount the knurling tool. Set centre height — use the same height as the turning tool. Off-centre setup is the second most common cause of poor patterns.
3. Square the wheels to the work. Both wheels must be parallel to the workpiece axis. Use a small engineer's square or a scrap dial gauge to check before plunging. Misaligned wheels produce a barber-pole pattern that walks along the shaft.
4. Position the wheel near the tailstock end. Knurl from the right (tailstock) side toward the chuck — gives you visibility and a free run-off.
5. Set RPM low. 40–80 for steel at 25 mm diameter. If you're not sure, go lower.
6. Flood with cutting oil. Soluble for steel, kerosene for aluminium. Don't dry knurl steel.
7. Plunge to depth quickly. Drive the cross-slide in by hand — about 0.5 mm per side for a single-wheel, 0.5–0.8 mm per side for a scissor knurler. Plunge in one motion, not in stages. This synchronises the pattern.
8. Check the pattern after one revolution. Stop the lathe. Look at the impression. If it's a clean diamond (or straight), proceed. If it's fuzzy or double-cut, retract, re-check the diameter, and start again — don't try to "deepen" a bad pattern by pushing harder.
9. Engage power feed. 0.2–0.5 mm/rev. Travel the length of the knurl in one steady pass.
10. Reverse feed and run back. Often improves the pattern definition — second pass cleans up displaced metal.
11. Optional second plunge. If the pattern is light, retract, advance another 0.2–0.3 mm, and feed again. Form knurling builds the pattern over multiple passes — don't try to get full depth on the first plunge.
12. Retract and inspect. Brush off chips, wipe down with rag, check for flaking or splitting.

Common knurling problems and fixes

Hand knurling and small lathes

Not every knurl needs a lathe. A hand knurler — a squeeze-grip tool with two opposing wheels — can knurl small workpieces clamped in a vice. The pattern quality is entirely operator-dependent, but it's a perfectly serviceable technique for repair work, one-offs, or knurling something already installed (e.g. raising the diameter of a worn shaft for press-fit refitting).

The technique: clamp the workpiece firmly. Squeeze the knurler onto the surface with even pressure. Rotate the workpiece (or rotate the knurler around the work) by hand or with a slow drill chuck. Maintain even squeeze pressure throughout the rotation. The pattern won't be as crisp as a lathe knurl but it'll grip.

For small hobby lathes (Sieg, Optimum, mini-lathes), scissor knurlers are mandatory. A bump-style single-wheel knurler will overload the spindle bearings on anything under a 1.0 m centre lathe. The radial force from a 1.0 mm pitch bump knurl on 20 mm steel can exceed 3 kN — easily enough to push small spindle bearings out of preload and damage them permanently.

Knurling on CNC vs manual lathes

Form knurling translates straight to CNC — same RPM, feed, plunge depth, calculation rules. Most CNC shops use scissor or revolving knurlers in the turret because the radial-load issue applies even more on CNC turrets where the toolpost is rigid but the workholding may not be.

Cut knurling is more common on CNC — it scales, repeats reliably, and produces a consistent pattern across thousands of parts. The wheel angle and feed need careful programming but once dialled in, a cut knurler delivers production-grade results without the indexing dance form knurling demands.

One CNC-specific issue: the spindle won't slow down on its own. Make sure the program calls a low S-value before the knurling block, otherwise the previous turning RPM (often 1,500–2,500) will turn the knurl into a smear at first contact.

Material considerations

Not every material knurls well. Hard rules:

• Mild steel, free-machining steel: ideal. Forms cleanly, strong pattern.
• Aluminium 6061-T6: good with kerosene. Aluminium 2011 (lead-bearing free-machining) is exceptional.
• Brass, bronze: excellent — clean pattern, dry knurling acceptable.
• Stainless 304: work-hardens fast — requires sulphurised oil and slow RPM. Cobalt or carbide wheels recommended.
• Stainless 316: like 304 but worse. Cut knurl if possible.
• Hardened steel (above 30 HRC): can't form knurl. Cut knurl or skip and design around it.
• Cast iron: poor — brittle, chips out instead of forming. Use only with cut knurler.
• Plastics (acetal, nylon, PEEK): form knurling fine, cut knurling cleaner. Watch heat — plastics melt, not work-harden.
• Spring steel, tool steel (annealed): form knurl with light depth, multiple passes. Hardened — cut knurl only.

Standards reference

For an Australian shop reading mixed German, American, and Japanese drawings, DIN 82 is the dominant reference. ANSI B94.6 turns up on US-imported equipment and tooling. Most modern engineering drawings call out "m × pitch" with the DIN pattern code.

Safety and finishing

Knurling generates sharp pattern crests immediately after forming. The fresh ridges feel like a fine file — they'll cut skin readily. Standard practice: knurl, then deburr with a fine file (light strokes, not aggressive) or a quick pass with 400-grit emery on a backing block. The deburring softens the crest tips without losing the grip.

For decorative work — cosmetic knobs, presentation pieces — finish the knurl with a wire brush wheel or fine emery to give a uniform polished crest. For grip-critical work — tool handles, gym equipment — leave the crests sharp.

PPE: safety glasses (chips fly, especially on cut knurling). Sleeves rolled up — knurling tools spin chips around the post. No gloves on a running lathe — basic lathe safety applies.

Need help selecting a knurling tool or wheel set for your application? Browse the Maxigear knurling range, contact the AIMS team or call us on (02) 9773 0122 — happy to talk through pitch, pattern, and tool type for your job.

Frequently Asked Questions

What is knurling and what is it for?

Knurling is the process of impressing or cutting a pattern of small ridges on the cylindrical surface of a workpiece — usually on a lathe. The pattern provides grip on tool handles and knobs, decoration on premium hand tools and barbells, or a controlled interference fit when the knurled part is pressed into a hole. The five common patterns under DIN 82 are straight (RAA), diagonal left or right (RBL/RBR), raised diamond (RGE), and depressed diamond (RGV).

What's the difference between cut knurling and form knurling?

Form knurling presses the pattern into the workpiece by displacing metal — no chips, just plastic deformation. The workpiece grows in diameter by about 70% of the pitch. Cut knurling uses an angled wheel that cuts chips like a milling tool — it removes material rather than displacing it, the workpiece doesn't grow, and it works on hard materials that form knurling can't handle. Form knurling is what most workshops do; cut knurling is mainly used in production environments and on hardened steel.

What pitch should I use for my knurling job?

Pitch is selected by workpiece diameter and application. For workpieces under 10 mm, use 0.5–0.6 mm pitch. For 10–25 mm, 0.8 mm pitch. For 15–35 mm, 1.0 mm pitch is the general-purpose default. For 30–80 mm, 1.5–1.6 mm. For coarse decorative or grip on workpieces over 50 mm, 2.0 mm pitch. Match the wheel teeth count to the workpiece circumference using N = π × diameter ÷ pitch.

How do I calculate the workpiece diameter for a clean knurl?

The workpiece circumference must equal a whole-number multiple of the pitch — otherwise the wheel skips and you get a double-cut pattern. Formula: diameter = (N × pitch) ÷ π, where N is a whole number. Worked example at 1.0 mm pitch: diameters of 9.55 mm (N=30), 12.73 (N=40), 15.92 (N=50), 19.10 (N=60), 23.87 (N=75), 31.83 (N=100). Form knurling lifts the finished diameter by ~70% of pitch, so turn the workpiece slightly smaller than the target finished size.

What RPM should I run for knurling?

Knurling is a slow operation. For mild steel at 25 mm diameter, run 40–80 RPM. Aluminium and brass tolerate higher (80–150 RPM). Stainless 304/316 needs slower (30–60 RPM) plus heavy sulphurised oil. Tool steel annealed: 20–40 RPM. The general rule from forum consensus and practical experience: low RPM, fast feed. Most knurling failures come from operators running normal turning RPM (300+) and feeding too slowly — exactly backwards.

Should I use cutting oil when knurling?

Yes — flooded soluble oil for steel, sulphurised oil for stainless, kerosene for aluminium. Cutting fluid keeps displaced metal and chips off the wheel, prevents loading, and keeps the workpiece cool enough to avoid surface work-hardening. Skipping fluid is the second most common cause of pattern flaking after running too fast. Brass and plastics generally don't need fluid.

Why is my knurl coming out as a double-cut or fuzzy pattern?

The workpiece circumference isn't a whole-number multiple of the pitch, so each tooth lands in a different position every revolution and you see two overlapping patterns. Recalculate the diameter using diameter = (N × pitch) ÷ π. Plunge the wheel quickly to half-depth on the first contact rather than slowly creeping in — a fast plunge synchronises the pattern from the first revolution, while slow infeed gives the wheel time to skip onto the wrong indexing.

Can I knurl on a small or hobby lathe?

Yes, but only with a scissor (clamp) or self-adjusting two-wheel knurler — never a single-wheel bump knurler. The radial force from a 1.0 mm pitch bump knurl on 20 mm steel can exceed 3 kN — easily enough to push small spindle bearings out of preload and damage them permanently. Scissor knurlers grip the work between two opposing wheels and the forces cancel out, so the lathe sees zero net radial load.

What's the difference between straight and diamond knurl?

Straight knurl (DIN 82 RAA) has parallel ridges along the workpiece axis — used for push-pull grip, knobs, and decorative work. Diamond knurl (RGE for raised diamond) is produced by two opposing helical wheels (one left-hand, one right-hand) at the same pitch, forming a diamond pattern of raised pyramids. Diamond gives the strongest grip and is the most common pattern on tool handles. Straight is simpler — only one wheel needed.

Can I knurl stainless steel?

Yes, but it's the hardest common material to knurl. Stainless 304 and 316 work-harden under pressure, which causes the surface to flake or split as the pattern forms. Use slow RPM (30–60), heavy sulphurised cutting oil (mandatory), cobalt or carbide knurling wheels rather than HSS, and consider cut knurling rather than form knurling on the harder grades. If it must be form-knurled, build the pattern over 2–3 light passes rather than one deep plunge.

Can I knurl aluminium?

Aluminium knurls beautifully — 6061-T6 forms a crisp pattern, and 2011 (lead-bearing free-machining) is exceptional. Run higher RPM (80–150) and use kerosene or aluminium-specific cutting fluid (regular soluble oil tends to gum up). Watch for chip welding to the wheel — aluminium can cold-weld to HSS at low speeds, so flush continuously.

Why is my knurled pattern flaking off after I make it?

Three common causes: the material work-hardened from too much heat (RPM too high, no cutting fluid) — the surface goes brittle and the pattern crests crack off. Or one of the wheels was stuck on its pivot pin (rust, swarf, dry pivot) and was scraping rather than rolling. Or the workpiece is a brittle material like cast iron that can't form a clean pattern. Fix: reduce RPM, flood with appropriate cutting oil, strip and clean the wheel pivots, or switch to cut knurling on hard or brittle material.

What standards apply to knurling?

DIN 82 is the dominant international standard — defines the pattern codes (RAA, RBL, RBR, RGE, RGV, RKE, RKV) and dimensional tolerances. ISO 13444 covers the drafting symbols used on engineering drawings. ANSI B94.6 is the US equivalent for knurling tools — turns up on imported American equipment. JIS B 0951 is the Japanese drawing-symbol standard. For an Australian workshop reading mixed European, American, and Japanese drawings, DIN 82 is the most-cited reference.

Can I knurl by hand without a lathe?

Yes — with a hand knurler, which is a squeeze-grip tool with two opposing wheels. Clamp the workpiece in a vice, squeeze the knurler onto the surface with even pressure, and rotate the workpiece (by hand or with a drill) while maintaining squeeze. Pattern quality is entirely operator-dependent — won't be as crisp as a lathe knurl — but it's perfectly serviceable for repair work, one-offs, or knurling something already installed. Useful for raising the diameter of a worn shaft for a press-fit refitting.

How does knurling affect workpiece diameter?

Form knurling lifts the workpiece diameter by approximately 70% of the pitch — a 1.0 mm pitch knurl raises the diameter by about 0.7 mm overall (0.35 mm per side). Cut knurling has minimal effect — the workpiece may shrink slightly because chips are removed. If you need a specific finished diameter after knurling, turn the workpiece slightly smaller before knurling — for form knurling, target = finished diameter minus 0.7 × pitch.