Buy Cobalt Drill Bits Online in Australia
Cobalt Drill Bit Selection — Quick Reference
Cobalt drill bits (M35 + M42) — 5% / 8% cobalt PREMIUM HSS-Co drill bits for STAINLESS STEEL + tough alloys + work-hardening materials. Workshop + production + maintenance. Higher heat tolerance + edge retention than standard HSS. See cobalt drill bit guide.
| Cobalt Drill Bit Type | Best For |
|---|---|
| M35 (5% Cobalt) Standard | Workshop stainless + tough materials |
| M42 (8% Cobalt) Premium | Heavy stainless + work-hardened |
| HSS-Co Standard Length (Jobber) | Workshop standard depth |
| HSS-Co Long Series | Deep drilling |
| HSS-Co Stub (Short) | Workshop precision shallow |
| HSS-Co Step Drill | Sheet metal + variable diameter |
| Metric / Imperial Range | Workshop standard |
| Sutton AU Manufactured | Patriot + reliable |
Critical: Use cutting LUBRICANT — even Cobalt heats up. Don't WORK-HARDEN stainless — let bit cut, don't rub. Match speed + feed to material. See cobalt drill bit guide for full selection. Brands: Sutton Tools, P&N, Bordo. Companion: drill bits, long drill bits, metric jobber drill sets, cutting lubricants.
Cobalt drill bits are high-speed steel (HSS) drills with 5% or 8% cobalt alloyed into the steel — designated M35 (5% Co) and M42 (8% Co). The cobalt content raises the bit's red-hot hardness, which means it keeps its cutting edge in materials that would burn out an ordinary HSS bit: stainless steel, hardened tool steel, Inconel, titanium and high-tensile fasteners.
Cobalt vs standard HSS — when does it matter?
- Stainless steel work — cobalt's the right choice. 304 and 316 work-harden the moment a dull bit slips, so you need a bit that stays sharp.
- Hardened steel up to ~38 HRC — cobalt handles it. Above that, switch to carbide.
- Repetitive production drilling — cobalt's longer tool life pays for itself.
- Mild steel, aluminium, timber — standard HSS or HSS-TiN is plenty; you're paying for capability you won't use.
For deep technical context on choosing between HSS, cobalt and carbide drills, read our Cobalt Drill Bit Guide and Carbide vs HSS comparison.
Companion ranges: Drilling · Jobber Drills
People Also Ask — Cobalt Drill Bits
Q: M35 or M42 cobalt bits — what does the extra cobalt actually buy you?
M35 bits contain 5% cobalt and suit workshop stainless steel and general tough-material drilling. M42 bits contain 8% cobalt and are the premium option for heavy stainless steel and work-hardened materials, offering higher heat tolerance and edge retention again over the M35.
Q: When should I use cobalt drill bits instead of standard HSS?
Cobalt is the right call for stainless steel work — 304 and 316 work-harden the moment a dull bit slips, so you need a bit that stays sharp — and for hardened steel up to around 38 HRC (above that, switch to carbide) and repetitive production drilling, where the longer tool life pays for itself. For mild steel, aluminium or timber, standard HSS or HSS-TiN is plenty; cobalt is capability you won't use there.
Q: How do I stop a cobalt drill bit overheating in stainless steel?
Use cutting lubricant — even cobalt bits heat up in stainless. Just as importantly, don't work-harden the material: let the bit cut rather than rubbing against the surface, and match your speed and feed to the material.
Q: What length options are cobalt drill bits available in?
Standard-length (jobber) for workshop-standard depth, long series for deep drilling, and stub (short) for precision shallow work. A step drill format is also available for sheet metal and variable-diameter holes.
Q: Which brands of cobalt drill bits does AIMS stock?
Sutton Tools (Australian manufactured), P&N and Bordo.