How to Choose a Cobalt Drill Bit Set for Metal
By Drill Hog® | Published: 2026-10-19
Category: Product Reviews
Learn how to pick the right cobalt drill bit set for metal. Compare M42 cobalt vs HSS, understand sizing, and find the best set for your shop.
Quick answer
For drilling hardened steel, stainless, or other tough metals, choose a solid M42 cobalt drill bit set like the Drill Hog® Super Cobalt M42+ sets. They outlast HSS bits and resist heat better, making them the right choice for metalworkers who need consistent performance.
Cobalt vs HSS: What actually changes
High-speed steel (HSS) bits work fine for soft metals like aluminum or brass, but they lose hardness quickly when drilling stainless or hardened steel. Cobalt bits—especially M42 grade—add cobalt to the steel alloy, letting the bit stay sharp at higher temperatures. That heat resistance is the main reason you pay more for cobalt.
The trade-off: cobalt bits are more brittle than HSS. Dropping one on a concrete floor can chip the cutting edge. If you mostly drill wood or plastic, stick with HSS and save money.
What M42 means and why it matters
M42 is a specific cobalt steel alloy that contains about 8% cobalt. It holds a cutting edge at red heat (around 1100°F), which is exactly what you need when drilling stainless or titanium. Standard M2 cobalt bits have less cobalt and soften sooner.
When a set says "M42+" like the Drill Hog® Super Cobalt sets, it usually means the alloy meets or exceeds M42 specs. That translates to longer run times between sharpenings for production work.
Fractional sizing: What you get in a 29-piece set
A 29-piece fractional set covers 1/16" to 1/2" in 1/64" increments. That range handles most common bolt and screw clearance holes, plus many pilot holes for tapping. You don't get metric sizes or larger diameters above 1/2", so if you regularly drill 5/8" holes, you'll need individual bits or a separate set.
The convenience of a complete indexed case—like the orange round case with belt clip on the Drill Hog® sets—keeps sizes organized and prevents losing the small bits on a job site.
Decision rules for choosing a cobalt drill bit set
- 1. Match the alloy to the metal: Use M42 cobalt bits for stainless steel, hardened steel, titanium, and cast iron. Use standard HSS or black oxide bits for mild steel, aluminum, brass, wood, and plastic. If you drill mostly stainless or hardened steel, go with M42 cobalt.
- 2. Choose the right size range: A 29-piece fractional set (1/16" to 1/2") covers most maintenance and fabrication work. If you need metric sizes or bits over 1/2", buy individual bits or a separate larger set. Check your most common hole sizes before buying.
- 3. Prioritize case quality: An indexed case with clear size markings and a secure latch keeps bits organized and prevents loss. Look for a case that fits in a tool belt or pouch if you work on site. A good case saves more time than the bits themselves.
- 4. Compare price per bit, not set price: Divide the set price by the number of bits. Premium M42 sets cost more per bit than HSS, but they last 3–5× longer in hard metals. That makes them cheaper per hole over time. Calculate cost per hole, not cost per set.
Product facts
- 29 Pc Cobalt Drill Bit Set Super Cobalt M42+ Plus Series Drill Hog® Special: 29 fractional sizes from 1/16" to 1/2" by 1/64ths, solid M42+ cobalt, orange round case with belt clip. You get every common fractional size in one organized case, so you don't waste time hunting for the right bit when drilling stainless or hardened steel.
29 Pc Cobalt Drill Bit Set Super Cobalt M42+ Plus Series Drill Hog® Special - 29 Pc Cobalt Drill Bit Set Super Cobalt M42+ Plus Series Drill Hog®: Same 29-piece M42+ set with identical size range and case design. This is the same core set—choose whichever listing fits your cart or budget; the bits and case are identical for metal drilling.
29 Pc Cobalt Drill Bit Set Super Cobalt M42+ Plus Series Drill Hog®
Who should buy a cobalt drill bit set
Best for
- Metal fabricators and machinists drilling stainless or hardened steel regularly
- Maintenance technicians who need one set that handles tough alloys without frequent resharpening
- DIY enthusiasts working on automotive or heavy equipment repairs involving hardened metal
Not for
- Woodworkers or drywall installers who rarely drill metal
- Anyone who needs metric sizes or bits larger than 1/2" in the same set
- Budget-focused buyers who only drill mild steel and aluminum occasionally
