Drilling stainless steel comes down to one core principle: keep the bit cutting, not rubbing. Stainless work-hardens quickly when a dull or fast-spinning bit slips instead of biting in, and once that happens the surface becomes genuinely harder to drill than it was a moment before. The fix is a sharp cobalt bit, slow speed, steady pressure, and constant lubrication — get those right and stainless drills more easily than its reputation suggests.
Why Stainless Steel Fights Back
Stainless steel isn’t inherently hard — most common grades start out relatively soft. The problem is work hardening: friction and heat from a slipping or dull bit transform the surface into a much harder state, and once that’s happened, continuing to push at the same settings just makes it worse. Drilling stainless successfully is really about avoiding that trigger in the first place, not overpowering the material.
What You Need
- Drill bit: cobalt HSS (M35/M42) for most jobs; a 135° split-point tip resists wandering better than the standard 118° point.
- Cutting fluid: dedicated cutting oil or tapping fluid — never drill dry.
- Center punch: to mark the hole and keep the bit from skating on the smooth surface.
- Clamp or vise: the workpiece must be secured, not hand-held.
- A drill or drill press with a slow-speed setting.
Step by Step
- Mark and center-punch the hole location so the bit seats immediately instead of wandering.
- Clamp the workpiece securely — vibration from an unsecured piece dulls the bit fast and increases the chance of slipping.
- Apply cutting fluid generously to the drill point before starting, and reapply as you go.
- Set a low speed — roughly half what you’d use on mild steel or wood. As a rough starting reference, a ¼” cobalt bit is commonly run in the 300–600 RPM range, but the right speed depends on bit diameter and equipment, so treat that as a starting point to adjust from, not a fixed number.
- Apply firm, continuous pressure so the bit produces a curled metal chip, not dust or a squeal. Dust or squealing means the bit is rubbing, not cutting — back off, add more fluid, and increase pressure rather than speed.
- Never let the bit spin in place against the metal. If you need to stop, retract the bit first rather than pausing mid-cut.
- On deep holes, retract periodically to clear chips and reapply cutting fluid.
Common Mistakes
- Using a standard (non-cobalt) bit at high speed
- Drilling dry
- Light pressure that polishes/hardens the surface instead of cutting it
- Letting a dull bit keep spinning and heat up instead of swapping it out
A Community Tip Worth Knowing (With a Caveat)
Some experienced fabricators on drilling forums report better results with a homemade lubricant — a spray bottle with a small amount of dish soap and a touch of bleach mixed with water — outperforming standard cutting oil in their own use. This is a shared personal technique from a machining community, not a manufacturer-recommended standard practice, so treat it as an option to experiment with rather than a replacement for proper cutting oil if you’re working to a specification.
If You’re Cutting Instead of Drilling
The same work-hardening principle applies to cutting stainless steel with a saw, grinder, or other tool — see our guide on how to cut stainless steel for method-specific technique.
Related reading: How to Cut Stainless Steel · How Do You Weld Stainless Steel?
