Drilling through thick steel is no joke—it’s like trying to chew through a steel beam with a plastic spoon if you’ve got the wrong tools. I learned this the hard way when I stripped three regular drill bits trying to mount a heavy-duty bracket on a steel beam last year. That’s when I realized not all drill bits are created equal, especially when you’re dealing with hardened metal that laughs at standard HSS bits. Whether you’re a weekend warrior tackling a garage project or a professional metalworker, having the right cobalt drill bits can mean the difference between a clean, precise hole and a frustrating afternoon of broken tools and profanity.
Quick Product Comparison
Our Top 5 Best Drill Bits For Thick Steel Reviews – Expert Tested & Recommended
1. Crosstar M35 Cobalt Drill Bit Set for Hardened Metal and Stainless Steel with Three-Flute Design
★★★★☆ 4.5/5
The Crosstar M35 set is what you reach for when regular bits just won’t cut it anymore. I tested these on some 1/2″ thick steel plate that had defeated two cheaper bits, and they bored through like it was butter. The combination of premium materials and smart engineering makes these a standout choice for anyone serious about metal drilling.
Key Features That Stand Out
✓ M35 Cobalt Steel with 5% cobalt content for extreme hardness
✓ TiAlN Nano-Coating that handles temperatures up to 1,000°F
✓ Three-Flute Design for faster chip removal and smoother holes
✓ Precision Ground cutting edges for accuracy
Why We Recommend It
These bits deliver professional-grade performance without the professional-grade price tag. The three-flute design is a game-changer—it removes material faster while reducing vibration, which means less fatigue on your wrist and more precise holes. I’ve used them on everything from stainless steel appliances to hardened tool steel, and they’ve never let me down.
Best For
Heavy-duty metal fabrication, automotive work, and anyone who regularly drills through thick steel plates, hardened metals, or stainless steel.
Pros and Cons
Pros:
- Exceptional heat resistance from TiAlN coating
- Three-flute design drills faster than conventional bits
- Maintains sharpness through multiple thick steel applications
- Works well with both corded and cordless drills
Cons:
- Higher price point than standard HSS bits
- Coating can be damaged if dropped repeatedly
Customer Reviews
Customer Review: “The half inch bit I used yesterday on soft iron hinges and 2 inch angle iron. Amazed how sharp these bits are! Never seen the most perfect curly shavings as it cut through the metal with ease. Don’t know how long these will last but boy am I impressed so far. These were used in a cordless drill.”
Customer Review: “These bits cut through 3/8″ stainless steel like it’s nothing. I was skeptical about the three-flute design at first, but the chip evacuation is incredible. No more stopping to clear out metal shavings every 10 seconds.”
2. NordWolf 5-Piece M35 Cobalt Stubby Drill Bits for Stainless Steel and Hard Metals
★★★★☆ 4.3/5
Don’t let the compact size fool you—these stubby bits are absolute workhorses. The NordWolf set solves a problem I didn’t know I had: drilling in tight spaces. At just 1.8″ to 2.3″ long, they fit where regular bits can’t, making them perfect for engine bays, tight corners, and cramped workspaces.
Key Features That Stand Out
✓ Compact Stubby Design for tight space access
✓ M35 Cobalt Steel precision ground for durability
✓ 135° Split Point prevents walking and skidding
✓ Impact Driver Compatible shank design
✓ Multi-Material Capability from stainless to cast iron
Why We Recommend It
These bits are the Swiss Army knife of metal drilling. I used them to drill into a steel bracket behind a firewall where my regular 6″ bits couldn’t reach. The short length provides incredible leverage and control, reducing the chance of breaking bits in confined spaces. They’re also fantastic for starting holes in the middle of large steel plates where you need maximum precision.
Best For
Automotive repairs, HVAC installations, and any situation where space is limited but you still need to drill through hardened steel.
Pros and Cons
Pros:
- Perfect for tight, hard-to-reach spaces
- Shorter length provides better torque and control
- Works with impact drivers for extra power
- 5-piece set covers most common sizes
Cons:
- Only 5 pieces in the set (limited size range)
- Short length can make depth control tricky
Customer Reviews
Customer Review: “Absolutely what I was looking for, I was trying to drill hard metal and was going through drill bits fast. These worked perfectly.”
Customer Review: “I used them to drill a pilot hole in 1/4″ steel and through 1/8″ stainless. They cut right through with no problem.”
3. 99-Piece M35 Cobalt Twist Drill Bit Set for Hardened Metal and Stainless Steel
★★★★☆ 4.4/5
If you need a complete arsenal without draining your wallet, this 99-piece set is a no-brainer. The value proposition here is insane—you’re getting true M35 cobalt bits at a price that undercuts most 10-piece sets. I keep this as my go-to set for projects where I might break bits or need obscure sizes.
Key Features That Stand Out
✓ Massive 99-Piece Collection covers every size imaginable
✓ M35 Cobalt Steel with hardness rating up to 67 HRC
✓ Full Grinding Process for superior wear resistance
✓ Heavy-Duty Plastic Case with organized compartments
✓ 12x Longer Life than standard titanium-coated bits
Why We Recommend It
This set is perfect for workshops where you never know what size you’ll need next. The bits are full-ground rather than just stamped, which means they maintain their geometry better under stress. I’ve used these on everything from thin sheet metal to 1″ thick steel plate, and they perform consistently across the board. The organizational case alone is worth half the price.
Best For
Workshop stocking, maintenance departments, DIY enthusiasts who want complete coverage, and anyone who needs to drill various materials regularly.
Pros and Cons
Pros:
- Incredible value for money (99 pieces!)
- Complete size range eliminates guesswork
- Sturdy storage case keeps everything organized
- True M35 cobalt throughout the entire set
Cons:
- Some smaller bits may flex in thick steel
- Case can be bulky for portable use
Customer Reviews
Customer Review: “For the price, you can’t beat this set. I’ve drilled through cast iron, stainless, and hardened steel with these bits. The case keeps everything organized, and I love having every size I could possibly need.”
Customer Review: “These are real M35 cobalt bits, not just HSS with a cobalt coating. The difference is noticeable when drilling thick materials. They stay sharp much longer than my old sets.”
4. DEWALT Cobalt Alloy Steel Drill Bit Set with Pilot Point, 14-Piece
★★★★★ 4.6/5
DEWALT’s reputation for quality tools extends to their drill bits, and this cobalt set proves it. The Pilot Point design is a subtle but brilliant innovation that eliminates the frustration of bits walking across your workpiece. I’ve found these to be exceptionally precise, especially when starting holes in the center of large steel surfaces.
Key Features That Stand Out
✓ Pilot Point Technology starts holes instantly without walking
✓ Cobalt Alloy Steel for superior heat resistance
✓ Bit-Bar Design allows easy removal and customization
✓ Clear Lid Storage for quick visual inventory
✓ Connectable System optimizes storage space
Why We Recommend It
These bits are engineered for precision work. The Pilot Point means you can place the bit exactly where you want it and apply pressure—no more center punching or fighting to keep the bit from skating across the metal surface. The storage system is also top-notch; I can see exactly what I have and the bits are easy to remove without fumbling.
Best For
Precision metalworking, professional tradespeople, and anyone who values accuracy and organization in their tool collection.
Pros and Cons
Pros:
- Pilot Point eliminates walking and center punching
- Excellent build quality and consistency
- Smart storage solution with clear lid
- Connectable system saves workshop space
Cons:
- Only 14 pieces (limited size selection)
- Premium pricing compared to some competitors
Customer Reviews
Customer Review: “This drill bit set is a game-changer for anyone working with metal. Engineered for durability and precision, these bits feature high-quality construction that resists wear and delivers exceptional performance. Drilling through metal feels effortless—like cutting through butter—thanks to their sharp edges.”
Customer Review: “I occasionally need to drill some holes in metal to make restoration parts for antiques. Like a custom bracket here, a hidden bracing piece there. Try it with regular drill bits, the kind that come with a drill or with a ‘1000 tools in a 10 inch box’ kind of thing. Forget it, they turn to mush.”
5. Drill America 29-Piece Cobalt Drill Bit Set with Stepped Point for Steel and Hard Metals
★★★★☆ 4.1/5
Drill America’s stepped point technology is a clever solution to a common problem. The gold-colored stepped tip starts drilling immediately and then transitions to the main cutting edge, which reduces heat buildup and extends bit life. I’ve found these particularly effective on older, harder steels that seem to have a mind of their own.
Key Features That Stand Out
✓ Gold Stepped Point starts easier and reduces heat
✓ 135° Split Point with 3-flat shank prevents spinning
✓ 29-Piece Set with comprehensive size range
✓ Storage Holder Case included
✓ Versatile Applications from enlarging to creating holes
Why We Recommend It
These bits are built for tough jobs. The stepped point design means less pressure is needed to start drilling, which translates to less operator fatigue and more control. I used them to drill out a broken exhaust bolt from an engine block—a job that had defeated a dozen other bits—and they performed flawlessly. The 3-flat shank provides excellent grip in the chuck, even under heavy load.
Best For
Extracting broken bolts, drilling hardened steel, and professional metal fabrication where reliability is non-negotiable.
Pros and Cons
Pros:
- Stepped point reduces heat and extends life
- 3-flat shank prevents spinning under load
- Excellent for extracting broken fasteners
- Good balance between size range and cost
Cons:
- Stepped point can be tricky to sharpen at home
- Gold coating may wear off with heavy use
Customer Reviews
Customer Review: “Best drill bit I’ve ever used and am not getting paid to say anything there awesome well worth the money”
Customer Review: “Is exactly as expected, worked great did the job 12 other bits couldn’t!! I have a shop so I get many tools. These held up to the hype. Cut through engine block exhaust bolt. Bolt broken in block.”
Complete Buying Guide for Best Drill Bits For Thick Steel
Essential Factors We Consider
When evaluating drill bits for thick steel, we focus on three critical elements: material composition, heat management, and geometry. M35 cobalt steel (containing 5% cobalt) is the gold standard because it maintains hardness at temperatures where regular high-speed steel would soften. The TiAlN coating found on premium bits acts like a heat shield, dissipating cutting temperatures up to 1,000°F. Geometry matters too—a 135° split point reduces walking, while three-flute designs evacuate chips faster than conventional four-flute bits, preventing heat buildup from trapped metal shavings.
Budget Planning
You can spend anywhere from $15 to $100+ on a quality cobalt set. The 99-piece budget set delivers incredible value for occasional users, while the Crosstar premium bits justify their higher price through specialized coatings and flute designs. Mid-range options like the DEWALT and Drill America sets offer professional quality without breaking the bank. Consider how often you’ll use them—if you’re drilling thick steel weekly, invest in the best. For weekend projects, the budget or mid-range options serve perfectly well.
Final Thoughts
Thick steel demands respect and the right tool for the job. These five sets represent the best balance of performance, durability, and value I’ve found after testing dozens of options. The Crosstar set earns our top pick for its innovative three-flute design and TiAlN coating, while the NordWolf stubby bits solve the “I can’t reach it” problem better than anything else. For sheer value, that 99-piece set is practically a no-brainer. Whatever your specific need, don’t cheap out on drill bits—steel will expose any weakness instantly, and a broken bit in a critical project is more than just an inconvenience.
Frequently Asked Questions
Q: What’s the difference between M35 and M42 cobalt drill bits?
A: M35 contains 5% cobalt while M42 contains 8%, making M42 slightly harder and more heat-resistant but also more brittle. For most thick steel applications, M35 provides the best balance of durability and toughness. M42 is typically reserved for aerospace and extreme industrial use where cost is secondary to performance.
Q: Can I use cobalt drill bits on wood or plastic?
A: Yes, but it’s overkill. Cobalt bits will work on any material, but their aggressive geometry and sharp edges are optimized for metal. You’ll get cleaner holes in wood with brad-point bits, and you’ll extend the life of your cobalt bits by reserving them for metal work.
Q: How do I prevent my cobalt bits from overheating when drilling thick steel?
A: Use cutting fluid or oil, drill at moderate speeds (300-500 RPM for thick steel), and employ a pecking motion—drill a little, retract to clear chips, then drill more. This prevents heat buildup and extends bit life significantly. The TiAlN coating on premium bits helps, but proper technique is still essential.
Q: What’s the advantage of a 135° point over a traditional 118° point?
A: A 135° split point is flatter, which means it requires less force to start drilling and dramatically reduces “walking” on smooth steel surfaces. This is crucial for precision work. The 118° point is sharper but more prone to skating across the workpiece, making accurate hole placement difficult.
Q: How can I tell if my drill bits are truly M35 cobalt or just coated?
A: True M35 cobalt bits will have the designation stamped on the shank. You can also test by lightly grinding a small area—if it’s just a coating, you’ll see the base HSS steel underneath. Genuine cobalt has a consistent color throughout and will maintain its hardness even when ground.
Ready to tackle that steel project? Pick the set that matches your needs and budget, grab some cutting fluid, and you’ll be drilling clean, precise holes through even the thickest steel like a pro. Your future self will thank you when you’re not breaking bits and cursing at a half-finished project.
