Best Drill Bits for Stainless Steel (Cobalt Picks + Buying Guide)

Stainless steel is one of the hardest common metals to drill. It work-hardens the moment a dull bit rubs instead of cuts, it holds heat in the cutting zone, and it will turn an ordinary hardware-store bit blue in seconds. The fix is simple: use cobalt drill bits (M35 or M42) with a 135° split point, run them slowly, and keep them cool.

We compared the most popular cobalt bits and sets on Amazon by alloy grade, point geometry, size range, case quality and long-term owner feedback. Here are the ones worth buying, plus a buying guide so you can pick the right bit for your own work.

Comparison Table

Drill bit set	Material	Point	Pieces / range	Best for
Drill America Cobalt Jobber Set	M35 cobalt	135° split	29 pcs, 1/16–1/2 in	Shop and serious DIY use
Bosch CO21B	M42 cobalt	135° split	21 pcs, 1/16–3/8 in	Hardest stainless and alloy steels
DEWALT Cobalt Pilot Point	Cobalt (M35 class)	Pilot Point split	Small set, common sizes	Cordless drills, jobsite
Milwaukee Red Helix Cobalt	Cobalt	135° split, variable helix	Multiple set sizes	Fast chip removal, long life
COMOWARE Cobalt Set	M35 cobalt	135° split	15 pcs, 1/16–1/2 in	Occasional stainless jobs

Note: product specifications can change between production runs. Always confirm the alloy grade and size list on the current Amazon listing before you buy.

1. Drill America 29-Piece Cobalt (M35) Jobber Set: Best Overall

Drill America is a favorite among machinists for one reason: the bits are made to industrial standards but priced for home shops. This set is M35 cobalt (about 5% cobalt), which means the hardness runs all the way through the bit rather than living in a thin coating. You can re-sharpen these bits many times and they still cut like cobalt.

The 135° split point starts without a center punch on flat stock and doesn’t skate across polished stainless. The 29 sizes run from 1/16 to 1/2 in in 1/64 in steps, which covers nearly every tap drill and clearance hole you’ll need.

• Pros: true M35 cobalt, full 1/64 in size range, re-sharpenable, sturdy metal index
• Cons: larger bits have full-size shanks, so 1/2 in needs a 1/2 in chuck

2. Bosch CO21B 21-Piece Cobalt (M42) Set: Best for Professionals

M42 cobalt has around 8% cobalt and is a step harder and more heat-resistant than M35. That matters when you are drilling thick 304 or 316 stainless, hardened bolts or tool steel all day. The Bosch set covers the most-used sizes from 1/16 to 3/8 in, and the 135° split point is ground cleanly.

• Pros: M42 grade for the hardest jobs, excellent heat resistance, good case
• Cons: M42 is slightly more brittle, so avoid side-loading small bits by hand

3. DEWALT Cobalt Pilot Point Set: Best for Cordless Drills

DEWALT’s Pilot Point tip is designed to start on contact and resist walking, which is exactly what you want when you’re holding a cordless drill against a stainless sink, rail or panel. The bits are a good match for 20V drills running in low gear, and the case is easy to keep in a work truck.

• Pros: very easy starts, tough jobsite case, widely available replacement bits
• Cons: fewer sizes than a full machinist set

4. Milwaukee Red Helix Cobalt Set: Best Long-Life Bits

Milwaukee uses a variable-helix flute that pulls chips out of the hole faster. With stainless, getting the chips and heat out is half the battle, so these bits tend to last longer in deep holes. The 135° split point and cobalt alloy make them a strong all-round choice.

• Pros: fast chip evacuation, good durability, available in several set sizes
• Cons: costs more than budget cobalt sets

5. COMOWARE 15-Piece Cobalt (M35) Set: Best Budget Pick

If you only drill stainless a few times a year, such as for a boat fitting, a kitchen backsplash or an exhaust bracket, an affordable M35 set like this one gets the job done. It covers 1/16 to 1/2 in in 15 common sizes and comes in a metal case.

• Pros: low price for real M35 cobalt, wide size range
• Cons: quality control is less consistent than premium brands

Buying Guide: How to Choose Drill Bits for Stainless Steel

Material: cobalt vs. titanium vs. carbide

• Cobalt (M35/M42): the best choice for most people. The cobalt is alloyed into the steel, so the bit stays hard at high temperatures and can be re-sharpened.
• Titanium-coated HSS: the gold coating reduces friction, but the core is regular HSS. Once the coating wears off the tip (often after a few stainless holes), it performs like a plain bit.
• Solid carbide: the fastest option in a rigid CNC machine or drill press, but brittle. In a handheld drill it will chip or snap.
• Plain HSS / black oxide: fine for mild steel and aluminum, but not a good choice for stainless.

Point angle: 135° split point

A 135° point is flatter than the common 118° point, which spreads the cutting load and stays sharp longer in hard metal. The “split” in the tip lets the bit start cutting immediately without walking, so you don’t need a pilot hole for small sizes.

Length: jobber vs. stub (screw machine)

Shorter bits flex less. If you’re drilling holes under 1/2 in deep in stainless, stub-length cobalt bits are stiffer and less likely to break. Jobber length is the standard all-purpose length found in most sets.

Size range

A 29-piece fractional set (1/64 in steps) covers almost everything. If you tap threads often, add a number or letter set, or buy individual tap drills such as a #7 for 1/4-20 threads.

How to Make Your Bits Last in Stainless

• Go slow: roughly 300–800 RPM for 1/4 in bits; slower for larger sizes.
• Push hard and steady: the bit must cut continuously. If it rubs, the stainless work-hardens.
• Use cutting oil on every hole.
• Never let the bit dwell in the hole without feeding.

For the full process, see our step-by-step guide on how to drill stainless steel.

Frequently Asked Questions

What is the best drill bit for stainless steel?

A cobalt drill bit (M35 or M42) with a 135° split point. It handles the heat that stainless generates and starts cleanly without walking.

Is M35 or M42 better for stainless steel?

M42 is harder and resists heat slightly better, so it lasts longer in thick or hardened stainless. M35 is a bit tougher and more forgiving in a handheld drill. For most DIY and general shop work, M35 is enough.

Can titanium drill bits drill stainless steel?

They can drill a few holes in thin stainless, but the titanium nitride coating wears off quickly. Cobalt bits last much longer.

Why do my drill bits keep going dull on stainless?

Usually the speed is too high or the pressure too light. Stainless needs low speed and firm feed. Without cutting oil, heat builds up and destroys the edge.

Can I sharpen cobalt drill bits?

Yes. Because cobalt bits are hard all the way through, they can be re-sharpened on a bench grinder or a drill bit sharpener and still cut like new.