What a Hole Saw Actually Is — Technical Definition
A hole saw is a cylindrical drilling tool that cuts a circular hole by sawing the perimeter rather than removing all the material in the hole. The cup-shaped saw has cutting teeth around its open mouth and a centre pilot drill that locates the cut. As the tool spins, the teeth saw a circular kerf around the circumference; the material inside the kerf — the "core" or "slug" — comes out intact when the cut breaks through. The cut diameter equals the hole saw's outside diameter, less the kerf thickness (typically 1.5–2 mm).
Compared to a twist drill bit cutting the same diameter:
- Far less material removed — only the kerf is cut, not the entire hole volume. A 75 mm hole saw removes about 5% of the material a 75 mm twist drill would.
- Lower power required — sawing a thin kerf needs a fraction of the torque that drilling the full diameter would.
- Larger diameters practical — 50–200 mm holes that would be impractical with twist drills are routine with hole saws. For the comparison across all drill bit types and applications, see our Drill Bit Types Guide.
- Limited depth — cut depth is limited to the cup's internal length (typically 38–50 mm). Deeper holes need step-cutting or annular cutters.
Hole saws span four main types defined by the cutting tooth material — bi-metal HSS, tungsten carbide-tipped (TCT), diamond grit, and tungsten masonry. Each type has a defined material range, cutting speed envelope, and service life. Mismatching the hole saw type to the material is the most common cause of premature tooth wear and the second most common cause of "the hole saw didn't work" complaints (the first being wrong RPM, covered later).
This guide is written for trade and industrial users — electricians, plumbers, fabricators, sheet-metal workers, and maintenance technicians cutting holes in metal, plastic, wood, and masonry as part of their daily work. The principles apply equally to DIY use; the brand and grade recommendations skew toward professional-grade tools that survive repeated use.
Hole Saw Types — Bi-Metal, TCT, Diamond, Masonry
Four core types cover the full range of materials a hole saw realistically cuts.
Bi-metal HSS hole saws (the workshop default)
Bi-metal hole saws have a body of low-carbon spring steel with high-speed steel (HSS) teeth electron-beam-welded to the cutting edge. Cobalt content (typically 8% in M42 grade HSS) increases hardness and heat resistance. Properties:
- Cuts: wood, plasterboard, plastic, mild steel up to ~6 mm, stainless steel (with reduced speed), aluminium, copper, brass
- Doesn't cut: hardened steel, cast iron above 200 HB, masonry, tile, glass, ceramic
- Service life: hundreds of holes in mild steel; thousands in plasterboard or wood
- Cost: mid-range — typical 60 mm bi-metal $30–60 trade price
Bi-metal is the AU workshop default. The Sutton H125 series (cobalt bi-metal) stocked at AIMS is a representative professional-grade range covering 14–127 mm diameters.
Tungsten carbide-tipped (TCT) hole saws
TCT hole saws have hardened tungsten carbide cutting edges brazed onto the saw body. The carbide is significantly harder than HSS and survives in materials that would dull bi-metal teeth quickly. Properties:
- Cuts: stainless steel (any grade), hardened steel, cast iron, fibre cement (Hardiplank, Villaboard), abrasive composites, multi-purpose use across mixed materials
- Doesn't cut: wood at high speed (TCT teeth are brittle and chip on impact), masonry (different carbide grade and tip geometry needed)
- Service life: 3–5× bi-metal in stainless steel and abrasive materials
- Cost: 2–3× bi-metal price for the same diameter
TCT is specified when bi-metal won't cut the material (stainless, hard steel, fibre cement) or when the application is high-volume production cutting where the longer life pays back the higher cost.
Diamond grit hole saws
Diamond hole saws have a steel body with industrial diamond grit bonded to the cutting edge — no individual teeth. The diamonds abrade the material rather than sawing it. Properties:
- Cuts: ceramic tile, porcelain, glass, stone, marble, fibreglass, ceramic-composite materials
- Doesn't cut: metal (diamonds graphitise on iron at cutting temperature), wood (cutting action is wrong)
- Critical requirement: water cooling. Diamond hole saws must be flooded with water during cutting to prevent diamond loss and substrate cracking. Dry cutting destroys the saw in minutes.
- Service life: 30–80 holes in tile depending on tile hardness
- Cost: mid-to-high; small diamond hole saws are inexpensive but wear fast
Tungsten carbide masonry hole saws
Distinct from TCT metal hole saws — masonry hole saws use a different tungsten carbide grade (toughness optimised over hardness) and a hammer-action cutting geometry. Properties:
- Cuts: brick, concrete, mortar, blockwork, cement render
- Doesn't cut: reinforcing steel within the masonry — hits rebar and stops; need a metal hole saw to clear it
- Drilling mode: hammer drill or rotary hammer required; standard rotary drill not enough
- Cost: mid-range; comparable to TCT
| Material | Right hole saw | Tool / cooling |
|---|---|---|
| Wood, plasterboard | Bi-metal HSS | Standard rotary drill, dry |
| Mild steel up to 6 mm | Bi-metal HSS | Cutting fluid, slow speed |
| Stainless steel | TCT | Cutting fluid, very slow speed |
| Cast iron, hardened steel | TCT | Cutting fluid, very slow speed |
| Fibre cement (Hardiplank) | TCT (multi-purpose) | Standard drill, dust mask, dry |
| Aluminium, brass, copper | Bi-metal HSS | Cutting fluid optional, moderate speed |
| Tile, porcelain, glass | Diamond grit | Water cooling mandatory, slow speed |
| Brick, concrete, blockwork | Masonry tungsten carbide | Hammer drill, dry |
Cutting Speed (RPM) — The Most-Missed Specification
Hole saw RPM is the single biggest factor in cut quality, tooth life, and successful completion. Wrong RPM kills hole saws. Cuts come from each tooth taking a controlled bite of material — too fast and the teeth skate on heated chips; too slow and the teeth grind without cutting. The relationship between hole saw diameter and target RPM is inverse: larger diameter = slower RPM.
Why RPM matters
Hole saws are specified by surface cutting speed (SFM in imperial, m/min in metric) — the speed of the cutting edge measured at the tooth tip. Bi-metal hole saws cut mild steel at approximately 25 m/min surface speed. A 25 mm bi-metal cutting at 25 m/min calculates to 318 RPM; a 100 mm bi-metal at the same surface speed calculates to 80 RPM. Same surface speed, very different drill RPM. For the broader cutting speed reference covering drill bits, taps, and lathe operations across HSS, cobalt and carbide tools, see our Drill Speed Chart and Cutting Speeds Reference.
| Hole saw diameter | Mild steel (bi-metal) | Stainless steel (TCT) | Wood (bi-metal) |
|---|---|---|---|
| 20 mm | ~400 RPM | ~150 RPM | ~1500 RPM |
| 30 mm | ~270 RPM | ~100 RPM | ~1000 RPM |
| 50 mm | ~160 RPM | ~60 RPM | ~600 RPM |
| 75 mm | ~110 RPM | ~40 RPM | ~400 RPM |
| 100 mm | ~80 RPM | ~30 RPM | ~300 RPM |
| 150 mm | ~50 RPM | ~20 RPM | ~200 RPM |
These are starting figures; refer to the specific hole saw manufacturer's data sheet for the cutting saw being used. The trend matters more than the exact numbers — most users run hole saws far too fast.
Variable-speed drills with electronic speed control hold the lower RPM under load. Fixed-speed drills don't — for serious metal cutting, a low-RPM drill press or a drill with a 2-speed gearbox in low gear is the right tool.
Common Hole Saw Sizes and What They're Used For
Hole saws come in graduated diameters; certain sizes are far more common than others because they match standard fittings, fixtures, and openings.
| Diameter | Common application |
|---|---|
| 17–25 mm | Conduit entries (20 mm conduit), cable glands, small electrical fittings |
| 25–32 mm | Cable glands (25 mm), Cat6 wall plates, small downlights |
| 32–40 mm | Larger conduit, electrical socket boxes, plumbing pipe entries |
| 40–54 mm | Door lock cylinder bores, pipe through-holes, small recessed lights |
| 54–70 mm | Door knob latches (54 mm bore + 25 mm latch), exhaust fan openings |
| 70–80 mm | Standard downlight openings (70 mm and 76 mm AU standard sizes) |
| 80–92 mm | Larger downlights, sub-floor vents, switchboard cable entries |
| 92–100 mm | Recessed light fittings, vent ducts, conduit entries |
| 100–127 mm | Large vents, range hood ducting (100 mm), spa pipe through-holes |
| 127–200 mm | Large duct work, industrial pipe through-holes, specialty applications |
The downlight standard
Australian recessed downlight fittings standardise on a small set of cut-out sizes — predominantly 70 mm and 76 mm for residential downlights, with 90 mm and 92 mm common in commercial. Electricians fit-out new homes cutting hundreds of these holes; specifying the downlight before specifying the hole saw is faster than the reverse.
Conduit-to-hole-saw sizing for electricians
The hole-saw size for an AU electrical conduit is not simply the conduit diameter — gland nuts and conduit fittings need clearance. Common AU electrical conduit sizes and the matching hole-saw diameter:
| Conduit nominal size | Conduit OD (mm) | Hole-saw diameter |
|---|---|---|
| 16 mm | ~16 | 20 mm |
| 20 mm | ~20 | 25 mm |
| 25 mm | ~25 | 32 mm |
| 32 mm | ~32 | 40 mm |
| 40 mm | ~40 | 50 mm |
| 50 mm | ~50 | 60 mm |
The hole-saw size matches the gland-nut OD plus small clearance, not the conduit OD. Always confirm against the specific gland-nut manufacturer data sheet — a few millimetres difference between brands is common.
Selecting a Hole Saw for Your Material
The four-factor selection process:
- Identify the material exactly. "Steel" isn't enough. Mild steel, stainless 304, stainless 316, hardened tool steel, cast iron, and Galvalume all need different hole saws or speeds. "Wood" isn't enough either — softwood, hardwood, treated pine, MDF, and plywood respond differently.
- Identify the material thickness. Hole saw cup depth (typically 38–50 mm) limits the maximum cut depth. Thicker material requires multi-step cutting from both sides or a different tool (annular cutter, plasma).
- Match hole saw type to material. Use the table earlier: bi-metal for wood/mild steel, TCT for stainless and hard steel, diamond for tile/glass, masonry-grade for brick/concrete.
- Specify the diameter. Match the application — fitting standard, fixture standard, or mating part dimension.
For mixed-material applications (multi-purpose TCT), pick the hardest material in the mix as the limiting factor. A TCT multi-purpose hole saw handles wood, fibre cement, and stainless in succession; a bi-metal would dull on the stainless cut.
Hole Saw Arbors and Mandrels
The hole saw itself doesn't fit a drill chuck — it threads onto an arbor (also called a mandrel) which holds the pilot drill and connects to the drill chuck. The arbor is often forgotten in first-time hole saw purchases.
Arbor types and compatibility
- Universal arbor — fits a range of hole saw sizes via a threaded back. Sutton's H112UA2 universal arbor at AIMS fits hole saws 32–54 mm; smaller arbors handle 14–30 mm; larger arbors above 54 mm. Most users own two arbors covering the small and large size ranges.
- Quick-change / quick-fit arbor — proprietary connection allowing fast hole saw swapping without unthreading. Convenient for high-volume work; locks the user into one brand's hole saw range.
- Hex shank / SDS arbor — for use in impact drivers (hex) or rotary hammers (SDS). Less common; check drill compatibility first.
Pilot drill
The pilot drill in the arbor centre locates the hole saw cut and prevents the saw from "walking" across the surface before the teeth engage. Standard pilot drills are HSS twist drills 6–10 mm diameter. They wear out with heavy use; replacement pilot drills are available separately.
Use a short pilot drill — screw-machine-length or stub-length, not a standard jobber-length. Long pilot drills wander off-centre as the saw begins cutting, especially in cordless drills with hand-held alignment. Short pilots stay rigid and on-mark. For production-volume work, drill-guide bushings (a hardened steel sleeve clamped to the workpiece, pilot drill running through the sleeve) eliminate wander entirely — the right setup for cutting hundreds of identical holes.
Cutting Technique — Pilot Drill, Pressure, Cooling
A correctly-specified hole saw cuts cleanly when used correctly. Common technique steps:
Step 1 — Mark the centre and pilot
Mark the cut centre with a punch (centre punch on metal, awl on wood, marking pen on tile). Position the pilot drill on the mark. Confirm the hole saw is square to the surface.
Step 2 — Start at low RPM
Begin cutting at the slowest reasonable RPM — pilot drill engages, hole saw teeth start kerf. Once the kerf is established (visible groove), maintain that RPM through the cut. Don't speed up.
Step 3 — Apply moderate, steady pressure
Push hard enough that each tooth takes a chip. Too light = teeth skate, glazing the cut. Too heavy = teeth break or the drill stalls. The right pressure makes a steady cutting noise (sawing sound, not whine, not chatter).
Step 4 — Cool the cut on metal
For mild steel, stainless, and aluminium, apply cutting fluid (CRC Tap-X, Trefolex, or equivalent) directly into the kerf. The fluid cools the teeth, lubricates the chip, and prevents tooth glazing. For diamond hole saws on tile, water cooling is mandatory — flooding the cut.
Counter-intuitive on stainless: stainless steel needs FIRM feed pressure despite the slow RPM. Light pressure on stainless lets the hard chromium-bearing surface work-harden under the tooth tips, glazing both the workpiece and the saw. Push enough to keep each tooth biting fresh material; the cut should produce continuous chips, not glittery dust.
Step 5 — Clear chips regularly
Withdraw the saw every few millimetres of cut depth to clear chips from the kerf. Trapped chips cause heat build-up, glazing, and slug-jamming inside the cup. On metal, chip clearing every 30 seconds is reasonable.
Step 6 — Slow down at break-through
As the saw approaches the back surface, reduce pressure. Punching through at full pressure causes burr-out on the exit side and risk of breaking the pilot drill or rim teeth.
Step 7 — Eject the slug
The cut "slug" is held inside the saw cup. Eject through the saw's slot or with a punch through the rear hole; never with a hammer on the saw teeth.
Common Failure Modes — and How to Avoid Them
Glazed teeth (smooth, polished, won't cut)
Cause: too high RPM, insufficient cutting pressure, no cutting fluid on metal. Once teeth glaze, the saw is finished — re-sharpening hole saws isn't economic. Fix: replace the saw; for the next cut, slow the RPM, increase pressure, and apply cutting fluid.
Broken teeth (chunks missing from rim)
Cause: too high cutting pressure, hitting embedded fastener or rebar mid-cut, dropping the saw. Fix: replace the saw; check the cut path for hidden fasteners or hardened inclusions; reduce pressure if drill is stalling.
Slug stuck in the cup
Cause: heat-welded, swarf-jammed, or normal interference fit on a clean cut. Three removal techniques in order of preference: (1) run the drill briefly in reverse — half a second of reverse rotation often breaks the slug free without any other intervention; (2) tap with a punch through the rear hole on the arbor — for hot-stuck slugs (welded), let cool first then tap; (3) for repeat sticking on the same job, install a slug-ejection spring inside the cup — pushes the slug out automatically as the saw withdraws.
Walking / pilot drill skipping
Cause: pilot drill blunt or worn; surface too smooth (polished steel, glazed tile); insufficient centre punch. Fix: replace pilot drill; punch a deeper centre dimple before cutting; use a bushing jig for production work.
Smoke and burning at cut
Cause: temperature too high — usually wrong RPM (too fast) or no cooling fluid. Fix: stop, let the saw cool, slow the RPM, apply cutting fluid before resuming.
When NOT to Use a Hole Saw
An honest specification guide should call out where hole saws are the wrong tool. Six situations where another method is correct:
- Material thicker than the cup depth (typically >50 mm). Hole saws can't cut deeper than their internal cup length. For deeper holes, use an annular cutter (purpose-built for thicker steel up to 100 mm) or step-cut from both sides.
- Production-volume metal cutting. Annular cutters are 3–5× faster than hole saws in steel and last longer. For high-volume hole drilling on the same machine, annular cutters with magnetic-base drill rigs are the right tool.
- Holes smaller than 14 mm. Small hole saws exist but twist drill bits are simpler, faster, and longer-lasting at small diameters. For graduated 4 mm to 35 mm holes in thin sheet metal, step drill bits are usually the right tool — see our Step Drill Bit Guide.
- Holes in living rebar-reinforced concrete. Diamond core drills with water cooling, or impact-rated SDS bits with hammer action, handle reinforced concrete. Masonry hole saws stop at the rebar.
- Cutting holes in safety glass, tempered glass, or laminated glass. These materials shatter or delaminate under hole saw pressure. Specify a glass-specific drill or have the holes cut by the glass supplier before tempering.
- Cutting through electrical cables, water pipes, or unknown services within walls/floors. Use a stud finder, wire detector, or cable scanner first. Hole saws cut blind into services with serious consequences — flooded floors, electrocution risk.
Hole Saw Brands in Australia
The AU hole saw market spans four broad tiers. Match the brand to the use intensity.
| Tier | Brands | Best for |
|---|---|---|
| Premium engineered | Starrett, Lenox, Milwaukee Hole Dozer, Bosch Pro | High-volume professional work; specialist applications (extremely hard steel, exotic materials) |
| Industrial / trade | Sutton (AU brand), Irwin, DeWalt, Makita | Daily trade and workshop use — electricians, plumbers, fabricators |
| Mid-range / DIY | Toolpro, Tactix, house brands | Occasional DIY use, light renovations |
| Consumer / supermarket | Generic imports | Single-use applications; one-off home jobs |
Sutton Tools is an Australian-manufactured cutting tool brand based in Melbourne — bi-metal cobalt hole saws (the H125 series) are stocked across the AU industrial supply chain and are the trade default for electricians, plumbers, and HVAC fitters. The Australian manufacture means consistent metallurgy, short supply chain, and AU-standard sizing.
Premium brands (Starrett, Lenox, Milwaukee) earn their price in high-volume professional work — site-installation crews cutting hundreds of downlight openings per week, or fabricators in heavy stainless. For mid-volume trade work, Sutton or equivalent industrial-grade is the right balance.
AIMS Industrial Hole Saw Range
AIMS stocks hole saws and accessories across the Sutton bi-metal cobalt range plus arbors and pilot drill replacements. The full range — H125 series in 14–127 mm diameters, universal arbors, accessories — is in the Hole Saws & Accessories collection. For sourcing larger diameters, TCT or diamond grit hole saws not in stock, or arbors matched to specific drill chucks, contact the AIMS team.
Companion guides: for the broader drill bit range and selection, see our Drill Bit Types Guide; for graduated sheet-metal holes in 4–35 mm sizes, see the Step Drill Bit Guide; for cutting speed and feed reference across drill bits, taps and lathe operations, see the Drill Speed Chart; for drill bit sizing in metric and imperial, see the Drill Bit Size Chart.
Frequently Asked Questions
What is a hole saw?
A hole saw is a cylindrical drilling tool that cuts a circular hole by sawing the perimeter rather than removing all the material in the hole. The cup-shaped saw has cutting teeth around its open mouth and a centre pilot drill that locates the cut. As the tool spins, the teeth cut a circular kerf; the material inside the kerf — the core or slug — comes out intact when the cut breaks through. Hole saws cut diameters from 14 mm to 200+ mm in materials including wood, mild steel, stainless steel, aluminium, plastic, fibre cement, tile, glass, and masonry — using different cutting tooth materials (bi-metal HSS, tungsten carbide, diamond grit, masonry carbide) matched to the substrate.
What's the difference between a bi-metal and a carbide hole saw?
Bi-metal hole saws have HSS teeth on a spring-steel body — the workshop default for wood, plasterboard, mild steel up to 6 mm, aluminium, and brass. Tungsten carbide-tipped (TCT) hole saws have hardened carbide cutting edges brazed to the saw body — used for stainless steel, hardened steel, cast iron, fibre cement, and abrasive composites where bi-metal teeth dull quickly. TCT costs 2–3× bi-metal but lasts 3–5× longer in stainless and abrasive materials. Choose bi-metal for general workshop and trade use; specify TCT when bi-metal can't cut the material or when production volume justifies the longer life.
What RPM should I run a hole saw at?
Hole saw RPM is inversely proportional to diameter — bigger diameter, slower RPM. Bi-metal in mild steel: 20 mm = ~400 RPM, 50 mm = ~160 RPM, 100 mm = ~80 RPM, 150 mm = ~50 RPM. Stainless steel TCT: roughly half those RPMs (slower for harder material). Wood with bi-metal: roughly 4× the steel RPMs (faster for softer material). The single most common mistake is running a hole saw at full drill speed regardless of diameter — a 75 mm hole saw at 2000 RPM glazes its teeth in 30 seconds. Slow the drill; the cut should sound like sawing, not whining.
What hole saw cuts stainless steel?
Stainless steel needs tungsten carbide-tipped (TCT) hole saws — bi-metal HSS teeth dull on stainless within a few cuts. Use cutting fluid (CRC Tap-X, Trefolex, or equivalent) directly in the kerf for cooling and lubrication. Run very slow RPM — for a 50 mm hole in stainless, 50–60 RPM is the right range. Apply firm steady pressure (light pressure causes glazing on stainless). Withdraw to clear chips every few millimetres of cut depth. The same TCT hole saws that work on stainless also handle mild steel and aluminium — over-spec but no performance penalty.
What hole saw cuts tile?
Diamond grit hole saws cut ceramic tile, porcelain, glass, and stone. The diamond grit abrades the material rather than sawing it. Critical: diamond hole saws must be flooded with water during cutting — dry cutting destroys the saw within minutes by causing diamond loss and substrate cracking. Run slow RPM (typically 200–600 RPM depending on diameter and material). Use light pressure — let the diamond grit do the work. Tile cuts can be made dry with very small diameter saws and short cuts but professional tile work flood-cools every cut.
How long does a hole saw last?
Service life varies enormously by hole saw type, material being cut, and operator technique. Bi-metal hole saws in plasterboard or wood: thousands of cuts. Bi-metal in mild steel: 100–500 cuts depending on grade. Bi-metal in stainless: 5–20 cuts before glazing. TCT in stainless: 50–200 cuts. Diamond in tile: 30–80 cuts depending on tile hardness. Operator technique (correct RPM, cutting fluid, chip clearing) can double or triple these figures; running too fast or dry can cut them by 90%. Budget plan: bi-metal as service item replaced at noticeable performance drop; TCT and diamond as longer-lived but specialist tools.
Can I cut concrete with a hole saw?
Yes — with a tungsten carbide masonry hole saw and a hammer drill or rotary hammer. Standard rotary drills don't have enough impact action to cut masonry effectively; the drill must hammer as it rotates. Masonry hole saws are distinct from TCT metal hole saws — different carbide grade, different tip geometry. They cut brick, concrete, and blockwork but stop at reinforcing steel — hitting rebar requires a separate metal hole saw to clear. For deep holes through reinforced concrete, diamond core drills with water cooling are the professional answer.
What size hole saw for a downlight?
Australian recessed downlight fittings standardise on a small set of cut-out sizes — predominantly 70 mm and 76 mm for residential downlights, with 90 mm and 92 mm common in commercial fittings. Always confirm the cut-out size from the specific downlight manufacturer's data sheet before cutting — wrong size means the fitting either falls through or doesn't fit. Most electricians keep a Sutton or equivalent bi-metal hole saw in 70 mm, 76 mm, 90 mm, and 92 mm in their van for residential and commercial fit-outs.
What is a pilot drill on a hole saw?
The pilot drill is the small twist drill bit at the centre of the hole saw arbor. It locates the hole saw cut on the surface and prevents the saw from "walking" across the surface before the teeth engage. Standard pilot drills are HSS 6–10 mm diameter; they cut a small centre hole that the hole saw teeth then enlarge to full diameter. Pilot drills wear out with heavy use — replacement pilot drills fit standard arbors. Without a working pilot drill, the hole saw drifts off-centre at start; the resulting hole isn't where the centre punch was.
What is a hole saw arbor?
The arbor (also called a mandrel) is the connector between the drill chuck and the hole saw — the saw threads onto the arbor at one end, and the arbor's hex shank fits the drill chuck at the other end. The pilot drill mounts in the arbor centre. Universal arbors fit a range of hole saw sizes via standard threads; quick-change arbors use proprietary connections for fast swapping. Arbors are sized for hole saw diameter ranges — small (14–30 mm), medium (30–54 mm), and large (54+ mm) typical. Most workshops own two or three arbors covering the diameter ranges they use; buying a hole saw without checking arbor compatibility is a common first-time purchase mistake.
Why does my hole saw smoke / burn?
Smoke from a hole saw means temperature too high — usually wrong RPM (running too fast for the diameter) or no cooling fluid on metal cuts. Stop immediately, let the saw cool, slow the drill speed, and apply cutting fluid (CRC Tap-X or equivalent) before resuming. Continued cutting with a smoking saw glazes the teeth (smooth polished cutting edges that won't cut) — once glazed, the saw is finished. The cut should sound like steady sawing, not whining; smell the cut — burning smell means something is wrong.
Why is my hole saw stuck — slug won't come out?
The cut slug stuck in the saw cup is normal — interference fit on a clean cut, swarf-jammed on metal, or heat-welded on hot cuts. Eject through the rear hole on the arbor with a punch tap (tap, don't hammer hard, against the slug from behind). For hot-welded slugs, let cool fully first; trying to eject a hot slug warps the saw cup. For repeat sticking on the same job, install a slug-ejection spring inside the cup — pushes the slug out automatically as the saw withdraws.
Can I sharpen a hole saw?
Bi-metal hole saws can technically be sharpened on a tooth grinder, but it's rarely economic — the labour to sharpen a 60 mm bi-metal hole saw professionally costs more than a new one. TCT hole saws can be re-tipped at specialist tool sharpening services; only justified for premium-grade saws used in specialist applications. Diamond hole saws aren't sharpened — when the diamond grit is worn, the saw is replaced. For the vast majority of hole saw users, replacement at end-of-life is faster and cheaper than re-sharpening.
What's the difference between a hole saw and an annular cutter?
Both cut circular holes by sawing the perimeter. Hole saws use teeth all around the cup mouth; annular cutters have a different tooth geometry (chip-clearing slots and a precise rim) plus a coolant-fed centre. Annular cutters cut faster in steel (3–5× a hole saw), produce a cleaner edge, last 10–20× longer, and handle thicker material (up to 100 mm depth versus hole saw's 50 mm limit). Trade-offs: annular cutters need a stronger drill (typically a magnetic-base drill rig), cost more per cutter, and aren't suitable for wood. For high-volume metal cutting, annular cutters; for general workshop and trade use, hole saws.
Where can I buy hole saws in Australia?
AIMS Industrial stocks the Sutton (Australian-manufactured) bi-metal cobalt hole saw range across 14–127 mm diameters, plus universal arbors and accessories. The dedicated Hole Saws & Accessories collection covers the full Sutton range. For premium brands (Starrett, Lenox, Milwaukee) specialist tool retailers and Total Tools / Sydney Tools stock the range. For consumer DIY use, Bunnings and similar carry house-brand and Toolpro / Tactix grade saws. Match the brand tier to the use intensity — daily trade and workshop use justifies the Sutton industrial tier; one-off home jobs are fine on consumer-grade.