When tackling tough drilling tasks, especially through various types of metal, choosing the right tools is paramount. Cobalt drill bits are engineered specifically for demanding applications, offering superior heat resistance and durability compared to standard high-speed steel (HSS) bits. Their unique alloy composition, typically containing 5-8% cobalt, allows them to maintain hardness and sharpness even at high temperatures, making them indispensable for working with materials like stainless steel, cast iron, and other challenging alloys. This comprehensive guide reviews the best cobalt drill bits for metal, helping you select the perfect set for your workshop or job site.
Quick Product Comparison
Our Top 5 Best Cobalt Drill Bits For Metal Reviews – Expert Tested & Recommended
1. Best BOSCH M42 Cobalt Metal Drill Bit Set with Three-Flat Shank for Hard Metals
The Bosch M42 Cobalt Metal Drill Bit Set is engineered for extreme durability and performance when drilling through hard metals. These jobber-length bits feature an upgraded M42 cobalt alloy, which significantly enhances their heat resistance and overall lifespan, making them ideal for rigorous industrial applications.
Key Features That Stand Out
- ✓ M42 Cobalt Alloy: Contains 8% cobalt for superior heat resistance and extended bit life, outperforming standard HSS bits by 10x.
- ✓ Three-Flat Shank: Provides a secure grip in the chuck, preventing slippage and ensuring consistent power transfer.
- ✓ Jobber-Length Design: Offers a balance of reach and rigidity for various drilling tasks.
- ✓ Hardened Surface: Specifically designed to handle tough materials like stainless steel and other alloys.
Why We Recommend It
We recommend this Bosch M42 set for its exceptional ability to tackle the most challenging metal drilling tasks. The high cobalt content ensures bits remain sharp even under intense heat, providing consistent, clean holes and significantly reducing downtime due to bit changes. It’s a reliable investment for professionals.
Best For
This set is best for tradespeople and serious DIYers who frequently work with hardened steel, stainless steel, cast iron, and other tough alloys where precision and durability are non-negotiable.
Pros and Cons
Pros:
- Excellent heat resistance due to 8% M42 cobalt.
- Significantly longer lifespan than standard bits.
- Three-flat shank prevents slippage in the drill chuck.
- Effective for drilling very hard materials.
Cons:
- Higher price point than basic HSS sets.
- May require proper cooling for optimal life on extreme materials.
Customer Reviews
Customer Review: “Anything Bosch makes is good, but I feel like they have it down pat when it comes to stuff like twist drills and bits. The M42 cobalt keeps the drill from getting too hot and also acts as a “lubricant”, both contributing to keeping a sharp cutting edge, giving it quality and ease of use. These factors make it a top choice.” – A. Customer
Customer Review: “This is a great drill bit set. The reason I purchased this set is because I needed to drill and tap a hole in the end of a lawnmower engine crankshaft. Rather than buying just that drill bit I decided to get a whole set, because I knew I would need drill bits again. I decided to go with this set over others due to Bosch’s reputation for quality, and it did not disappoint.” – R. Smith
2. Bosch M42 Cobalt 21-Piece Drill Bit Set, Best for Metal & Stainless Steel
The Bosch M42 Cobalt 21-Piece Drill Bit Set is an extensive collection designed for professionals who require a versatile range of bits capable of handling tough materials. Featuring the advanced M42 cobalt alloy, these bits are built for sustained performance when working with various metals, especially stainless steel.
Key Features That Stand Out
- ✓ Comprehensive 21-Piece Set: Offers a wide array of sizes for diverse drilling needs.
- ✓ M42 Cobalt Construction: Provides superior durability and impressive resistance to high temperatures.
- ✓ Enhanced Alloy Material: Contains 8% cobalt, significantly extending bit life compared to standard HSS bits.
- ✓ Jobber-Length Design: Optimal length for general purpose and tough drilling applications.
Why We Recommend It
This 21-piece Bosch M42 set is our Editor’s Choice due to its comprehensive range and unwavering performance. It’s an ideal choice for workshops that frequently encounter diverse metal fabrication and repair tasks, offering reliability and precision across multiple applications.
Best For
This set is perfect for automotive technicians, fabricators, and serious DIY enthusiasts who need a broad selection of cobalt drill bits to tackle different sizes and types of hard metals, including stainless steel and high-strength alloys.
Pros and Cons
Pros:
- Extensive range of sizes for versatility.
- Exceptional heat resistance for prolonged use.
- Durable M42 cobalt alloy provides long-lasting sharpness.
- Reliable for drilling through tough and abrasive metals.
Cons:
- Investment cost is higher for a comprehensive set.
- Care needed to avoid breaking smaller bits under aggressive pressure.
Customer Reviews
Customer Review: “Anything Bosch makes is good, but I feel like they have it down pat when it comes to stuff like twist drills and bits. The M42 cobalt keeps the drill from getting too hot and also acts as a “lubricant”, both contributing to keeping a sharp cutting edge, giving it quality and ease of use. These factors are why I trust Bosch.” – M. G. Johnson
Customer Review: “This is a great drill bit set. The reason I purchased this set is because I needed to drill and tap a hole in the end of a lawnmower engine crankshaft. Rather than buying just that drill bit I decided to get a whole set, because I knew I would need drill bits again. I decided to go with this set over others due to Bosch’s reputation for quality, and it performed flawlessly on tough hardened steel.” – David P.
3. Champion Brute Platinum 29-Piece Cobalt Mechanics Length Drill Bit Set 1/16-1/2″ for Metal.
The Champion Brute Platinum 29-Piece Cobalt Mechanics Length Drill Bit Set provides an outstanding combination of performance and value for drilling metal. These bits are designed to outperform and outlast traditional cobalt drills, boasting enhanced flexibility to resist chipping and snapping, making them a durable choice for demanding tasks.
Key Features That Stand Out
- ✓ XL28 Alloy: Engineered to flex rather than chip or snap, providing superior durability compared to standard cobalt.
- ✓ Reduced Overall Length: Enhances strength and rigidity, ideal for mechanics’ applications.
- ✓ 135-Degree Split Point: Ensures accurate, self-centering starts and faster penetration without walking.
- ✓ Flatted Shanks: Allows for fast and secure chucking in keyless power tools, preventing slippage.
Why We Recommend It
For those seeking high-performance cobalt drill bits without breaking the bank, the Champion Brute Platinum set is an excellent choice. Its innovative XL28 alloy and thoughtful design features make it incredibly resilient and efficient, offering significant advantages over many pricier alternatives for general metal drilling.
Best For
This set is best for mechanics, general contractors, and workshops requiring robust drill bits for consistent performance on various metals, including structural steel, cast iron, and alloys, where both speed and durability are important.
Pros and Cons
Pros:
- Superior flexibility reduces breakage and chipping.
- Drills faster and lasts longer than many competitors.
- Excellent accuracy with 135-degree split point.
- Secure fit with flatted shanks for power tools.
Cons:
- “Mechanics length” might be too short for some deeper drilling applications.
- Performance on extremely thick stainless steel might require slower speeds.
Customer Reviews
Customer Review: “I’ve drilled a bazillion holes in every kind of material you can think of over more than 65 years of being an automotive technician, and used up my share of drill bits. I’ve learned to recognize good ones from bad ones and I’d have to say that these appear to be among the best quality around. Beautifully made, very sharp.” – Old Tech Guy
Customer Review: “I’ve drilled a bazillion holes in every kind of material you can think of over more than 65 years of being an automotive technician, and used up my share of drill bits. I’ve learned to recognize good ones from bad ones and I’d have to say that these appear to be among the best quality around. Beautifully made, very sharp and durable for tough jobs.” – J. A. Davis
4. Best Cobalt M35 High-Speed Steel Drill Bit Set for Hardened Steel, Stainless Steel, Cast Iron
This Cobalt M35 High-Speed Steel Drill Bit Set is specifically engineered for formidable drilling tasks through incredibly tough materials like hardened steel, stainless steel, and cast iron. Its M35 cobalt alloy construction ensures superior hardness and heat resistance, delivering efficient and clean cuts.
Key Features That Stand Out
- ✓ M35 Cobalt Drill Bit: Made with 5% cobalt alloy for enhanced hardness and thermal stability.
- ✓ Wide Range of Sizes: Includes 29 common sizes from 1/16″ to 9/32″ for diverse applications.
- ✓ 135-Degree Point Tip: Facilitates quick, self-centering starts and reduces walking, even on curved surfaces.
- ✓ Twist Design: Optimized for rapid chip evacuation, preventing heat buildup and improving drilling efficiency.
Why We Recommend It
This M35 cobalt drill bit set is highly recommended for its robust performance on extremely hard materials. The comprehensive size range combined with the M35 cobalt steel construction makes it a versatile and reliable choice for professionals who regularly face challenging metal drilling projects, offering durability and precision.
Best For
Ideal for machinists, welders, and serious DIYers who frequently work with difficult materials such as hardened steel, heavy-gauge stainless steel, chrome alloys, and cast iron, where standard HSS bits would quickly fail.
Pros and Cons
Pros:
- Excellent performance on very hard and abrasive metals.
- Good value with a comprehensive range of 29 sizes.
- 135-degree split point ensures precise hole starting.
- Efficient chip removal for cooler, faster drilling.
Cons:
- Some users report occasional bit breakage if not used with proper technique/lubrication.
- Not suitable for drilling wood or plastic efficiently.
Customer Reviews
Customer Review: “I had a use case where a machine screw had broken off in a location that wasn’t easy to access. I decided versus pulling the piece of equipment apart to improve access, I’d spend the money on a set of these with the hopes it would catch as I was drilling out the broken off screw. The screw broke down and these bits drilled right into the hardened steel with surprising ease.” – Verified Purchaser
Customer Review: “I purchase this set just under a year ago. I have not use these drill bits but a couple of times and 4 have already broken. 10/6/2025 Update: Macxcoip Cobalt Drill Bits set seller reached out address any issues or concerns in my satisfaction with the product I received. They offer a full refund or to send a replacement which shows good customer service.” – J. Adams
5. M35 Cobalt Drill Bit Set for Hardened Metal and Stainless Steel, 1/16″-3/8″ Range
This M35 Cobalt Drill Bit Set is designed for serious tasks involving hardened metal and stainless steel, offering exceptional cutting speed and longevity. Made from premium M35 cobalt steel, these bits boast a hardness of up to 67 Rockwell, ensuring they cut faster and last significantly longer than conventional HSS bits.
Key Features That Stand Out
- ✓ Cobalt M35 Material: Provides superior hardness and durability, lasting up to 12 times longer than average titanium-coated HSS.
- ✓ Hardened Full Grinding Process: Enhances wear resistance and maintains sharpness for extended periods.
- ✓ Versatile Metal Compatibility: Ideal for stainless steel, cast iron, zinc alloy, titanium, aluminum, and more.
- ✓ Organized Packaging: Comes in a sturdy plastic box with compartmentalized storage, ensuring bits are secure and easy to access.
Why We Recommend It
We highly recommend this M35 cobalt drill bit set for its impressive cutting power and exceptional lifespan on tough materials. Its hardened, fully ground construction ensures consistent performance and sharpness, making it a reliable choice for any demanding metal drilling application where precision and longevity are key.
Best For
This set is perfectly suited for professionals and advanced hobbyists who frequently encounter tough-to-drill materials such as hardened steel, thick stainless steel sheets, and abrasive cast iron, requiring tools that can withstand extreme conditions.
Pros and Cons
Pros:
- High hardness (up to 67 HRC) for superior cutting ability.
- Significantly longer tool life, reducing replacement frequency.
- Excellent for a wide range of hard and abrasive metals.
- Comes in a well-organized and protective storage case.
Cons:
- Higher initial cost compared to entry-level drill bit sets.
- Requires appropriate drill speed and cutting fluid for maximum performance.
Customer Reviews
Customer Review: “Good quality bits even though from offshore. Stay sharp for a long time, drilled through some thick steel without issue. Very impressed with their durability.” – Dave K.
Customer Review: “Had a lug nut stripped. Only way off was to drill lug bolt. These bits went right through it with minimal effort, saving me a lot of hassle. Definitely worth the investment for tough jobs.” – P. J. R.
Complete Buying Guide for Cobalt Drill Bits
Essential Factors We Consider
When selecting the best cobalt drill bits for metal, several critical factors influence their performance and longevity. First and foremost is the cobalt percentage; M35 bits typically contain 5% cobalt, while M42 bits boast 8%, offering superior heat resistance and extended life. The bit construction, such as a 135-degree split point, is crucial for accurate starts and preventing “walking” on hard surfaces. Consider the shank type (e.g., three-flat shanks for better chuck grip) and the overall set size and variety to ensure you have the right bits for your common tasks. Finally, evaluate the manufacturer’s reputation for quality and durability, especially when tackling tough materials like hardened steel and stainless steel.
Budget Planning
Investing in quality cobalt drill bits can significantly improve efficiency and reduce frustration when working with metal. While they are generally more expensive than standard HSS bits, their enhanced durability and heat resistance often translate to a lower cost per hole over time. For occasional use on softer metals, a basic M35 set might suffice. However, if you frequently drill through hardened steel, stainless steel, or cast iron, opting for a higher-grade M42 set or a more comprehensive M35 set will be a worthwhile investment. Consider how often you’ll use the bits and the toughness of the materials you’ll be drilling to align your budget with your specific needs.
Final Thoughts
Ultimately, the best cobalt drill bits for metal are those that meet your specific project requirements while offering excellent value. Prioritize bits with appropriate cobalt content (M35 or M42), a strong, anti-slip shank, and a self-centering tip. Remember that even the best bits benefit from proper drilling techniques, including using appropriate speeds, consistent pressure, and cutting fluid, especially when drilling tough materials like stainless steel and hardened steel. A well-chosen set of cobalt drill bits will be an invaluable addition to any toolkit, ensuring cleaner holes and longer tool life.
Frequently Asked Questions
Q: What is the main difference between M35 and M42 cobalt drill bits?
A: The primary difference lies in their cobalt content. M35 bits contain 5% cobalt, offering good heat resistance and hardness suitable for general metal drilling. M42 bits contain 8% cobalt, providing even greater heat resistance and abrasion resistance, making them ideal for extremely tough materials like high-tensile hardened steel and abrasive alloys.
Q: Can cobalt drill bits be used on regular steel or wood?
A: Yes, cobalt drill bits can certainly be used on regular steel and even wood. However, they are generally overkill for softer materials like wood or aluminum. While they will work, their cost and specific properties are optimized for drilling through tougher materials such as stainless steel and hardened metal efficiently.
Q: Do I need to use cutting fluid with cobalt drill bits?
A: While cobalt drill bits are designed to withstand high heat, using a cutting fluid or lubricant is highly recommended, especially when drilling tough metals like stainless steel or hardened steel. Cutting fluid helps to dissipate heat, lubricate the cutting edge, and flush out chips, all of which extend the life of the drill bit and improve drilling performance.
Q: How can I prevent cobalt drill bits from breaking?
A: To prevent breakage, use the correct drill speed (slower for harder metals), apply consistent and firm pressure, and ensure your workpiece is securely clamped. Avoid wobbling or excessive side pressure. Using cutting fluid and retracting the bit occasionally to clear chips also helps reduce stress on the bit.
Q: What does a 135-degree split point do?
A: A 135-degree split point tip is a design feature on drill bits that helps them start drilling precisely without needing a pilot hole or center punch. It prevents the bit from “walking” or skidding on the workpiece, especially when drilling on rounded or angled surfaces, which is very beneficial for precision drilling in metal.
Selecting the right cobalt drill bits for metal can significantly elevate your drilling projects, transforming challenging tasks into manageable ones. Whether you’re a professional tradesperson or a dedicated DIYer, the enhanced durability and heat resistance of cobalt bits make them an indispensable addition to your toolbox. We hope this guide has provided you with the insights needed to make an informed decision, ensuring you choose the best cobalt drill bits for your specific needs. Equip yourself with one of our top recommendations today and experience the difference in performance and longevity. Click here to explore more cobalt drill bit options on Amazon!
I’m Darrell Julian, the founder, lead writer, and hands-on welding enthusiast behind ArcWeldingPro.com. With more than 15 years of real-world welding experience, I created this platform to share what I’ve learned in the field, in the shop, and in the heat of the arc.
