When you need to drill through hardened steel, choose cobalt or M35 HSS drill bits designed for high heat and tough materials. This guide compares five high-performing sets, highlighting who each product is best for, and why they stand out. Whether you’re a do-it-yourselfer, a professional fabricator, or a hobbyist tackling heavy metal, these picks help you minimize effort and maximize precision.
Product Comparison at a Glance
| Product | Best For | Key Benefit |
|---|---|---|
| MACXCOIP Cobalt Drill Bit Set | General hardened metals, stainless steel, cast iron | Broad size range with robust M35 cobalt for fast cutting |
| Sinyeenglon Hex Shank Cobalt Drill Bit Set | Impact-rated drilling with hex shank | Solid bonding and high torque stability |
| Crosstar M35 Cobalt Drill Bit Set | Hard metals and stainless steel | TiAlN coating plus three-flute design for cool, clean holes |
| Pro Edge Technology 13pcs Cobalt Bit Set | Value-focused hardened metal projects | Cost-effective with 13 sizes and 135° split point |
| ForgeWorx 1/4 Inch Cobalt Drill Bits | Heavy-duty steel, titanium alloys | TiAlN-coated, durable M35 cobalt, 1/4″ hex shank |
MACXCOIP Cobalt Drill Bit Set, 13Pcs
The MACXCOIP 13-piece set uses M35 cobalt for faster cutting in hardened metals and plastics. The bits range from 1/16″ to 1/4″ to cover common drilling tasks. The 135-degree point helps the bit center quickly, reducing wandering. Best for: general-purpose drilling in stainless steel, cast iron, and other hard materials, plus wood and plastic as a lighter use case. Caution: sporadic cutting on extremely hard alloys may require pre-drilling or lubrication to extend bit life.
Sinyeenglon Hex Shank Cobalt Drill Bit Set
This 13-piece M35 cobalt set features a solid bonding 1/4 hex shank to resist loosening under heavy torque, making it well-suited for impact drivers. The design aims to minimize radial runout and improve concentricity, boosting accuracy on tough materials. Best for: use with impact drivers when drilling through hardened metals. Caution: the hex shank design, while secure, may require compatible chucks in some older tools.
Crosstar M35 Cobalt Drill Bit Set (21pcs)
Designed for hardened metals, these 21 bits feature a TiAlN coating that resists heat up to 800°C, enabling longer life under heavy use. The triple-flute geometry improves chip ejection and hole quality, with better wall finish and reduced bit walk. Best for: precision drilling in stainless steel, hardened cast iron, and other hard materials. Caution: TiAlN coating can wear with extremely abrasive materials; avoid overheating without proper feed rate.
ZELCAN 10 Sizes Titanium Step Drill Bit
Although a step drill rather than a traditional twist drill, this set covers many sheet metal tasks with 10 step sizes from 1/4″ to 1-3/8″. The tri-flatted shank helps prevent slipping in chucks. Best for: electricians and DIYers drilling holes in sheet metal quickly. Caution: step bits can dull if used on hardened steel; use for appropriate materials only.
Pro Edge Technology 13pcs Cobalt Drill Bits
This 13-piece set emphasizes cost efficiency with cobalt HSS and M35 material, featuring 1/16″ to 1/4″ sizes and a 135° split point for self-centering drilling. Best for: projects needing multiple common sizes without paying a premium. Limitation: price-per-bit advantage varies with market; ensure the set matches your exact size needs before purchasing.
ForgeWorx 1/4 Inch Cobalt Drill Bits
The ForgeWorx set includes two 1/4″ cobalt drill bits with a TiAlN coating, designed for hard metals and high heat environments. The heavy-duty M35 cobalt construction aids durability and performance in steel, cast iron, and titanium alloys. Best for: quick, durable drilling through tough metals. Caution: these are larger bits; ensure your tool can accommodate a 1/4″ hex shank and length requirements.
Buying Guide
What should you consider when buying drill bits for hardened steel?
- Material: M35 cobalt (5% cobalt) provides higher heat resistance and wear life than standard HSS. This is essential for through-hardened steel applications.
- Coating: TiAlN coatings can dramatically extend bit life by resisting heat and reducing friction, especially at higher speeds.
- Tip geometry: A 135-degree split point helps with self-centering and reduces walking in hard metals.
- Shank style: Hex shanks resist slipping under high torque; ensure your drill chuck supports the shank size.
- Flute design: More flutes (like three-flute designs) improve chip ejection and reduce heat buildup.
- Size range: A set that covers common sizes (1/16″ to 1/4″ or larger) saves time switching bits.
- Application fit: For extremely hard alloys, consider specialized cobalt sets or step bits for sheet metal tasks.
FAQ
- Q: Can normal HSS bits cut through hardened steel? A: Not efficiently. Hardened steel requires cobalt or specially coated HSS bits for heat resistance and wear life.
- Q: Are hex shanks necessary for impact drivers? A: Hex shanks reduce slippage under high torque, making them preferable with impact mechanisms.
- Q: Do step drill bits work on hardened steel? A: Step bits are best for sheet metal; use traditional twist bits for through-hardened blocks.
- Q: How should I prevent bit wandering? A: Choose a bit with a split-point design and ensure proper centering before drilling.
- Q: Do coatings affect drilling speed? A: Coatings reduce heat buildup, which can maintain faster cutting over longer periods, especially on hard metals.