6 Best Drill Bits For Hardened Metal in 2026
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For drilling into hardened steel, stainless steel, or cast iron, you need a drill bit made of tougher stuff. Our top pick is the Bosch CO14B Cobalt Drill Bit Set, which wins for its excellent balance of heat resistance, durability, and a practical size range.
Other solid choices include the IRWIN M35 for maximum heat resistance and the Makita Impact Gold for use with an impact driver. Hardened metal can quickly ruin standard bits, so selecting the right material and geometry is critical for both success and bit longevity. This guide draws on specifications, expert analysis, and owner feedback patterns to help you choose the right bit set for your specific project needs.
Top 6 Drill Bits For Hardened Metal in the Market
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The Best Drill Bits For Hardened Metal, Reviewed
Bosch CO14B Cobalt Drill Bit Set
What We Like
- M42 cobalt alloy provides 10x life vs. standard bits
- Thick web-helix design adds stability in tough materials
- High heat resistance for extended drilling sessions
- Versatile size range covers 1/16-inch to 1/2-inch needs
Trade-offs
- 14-piece set offers fewer bits than some 29-piece competitors
The 8% cobalt M42 alloy is the key here, delivering a claimed tenfold lifespan over standard bits and the heat resistance needed to bore into stainless steel or cast iron without immediately dulling. This 14-piece set hits a practical sweet spot for a workshop, providing a solid range from 1/16-inch to 1/2-inch. The thick web-helix design gives these bits extra backbone, reducing deflection and chatter when you’re putting pressure on hardened metal. For the tradesperson or serious DIYer who regularly encounters tough materials, this set builds its reputation on durability and consistent performance.
You are getting a focused, quality assortment rather than a massive count. Compared to a bulkier 29-piece set like the Milwaukee Red Helix, the Bosch CO14B’s more compact 14-piece lineup and smaller case are easier to organize in a packed toolbox. The research and owner feedback highlight the value: you get the premium M42 cobalt material and a wider maximum size than some other sets, for only a modest cost increase. It’s a set built for the job, not just to fill a case.
IRWIN M35 Cobalt Drill Bit Set
What We Like
- 5% cobalt for high heat resistance
- 135-degree split point minimizes walking
- Heavy-duty web construction for durability
- Comprehensive 29-piece size range
Trade-offs
- Case dimensions are large at 12.3 inches wide
- No weight listed, suggesting a lighter-duty case
- Jobber-length bits limit depth in thick material
The 5% cobalt alloy steel is the key here, giving these bits a serious advantage when drilling into hardened steel where friction builds intense heat. This composition lets you push harder for longer before the bit loses its temper, making it a solid choice for repetitive metal fabrication or repair jobs. The 135-degree split point starts cleanly on curved surfaces, so you spend less time center-punching and more time making holes.
The trade-off is the jobber length and the sizable plastic case. You won’t be drilling deep into I-beams, and the case takes up a real chunk of bench space. For a more compact, workshop-friendly kit with similar heat resistance, compare the footprint to the Bosch CO14B set. If your primary concern is beating the heat on thick, hard metal, this IRWIN set’s material specification delivers.
Makita Impact Gold Titanium Drill Bit Set
What We Like
- TiN coating lasts 2.5x longer than non-coated bits
- Split point geometry reduces walking for faster starts
- Impact-rated for use in 1/4" hex impact drivers
- Drills a wide range of materials including hardened metal
Trade-offs
- At 14 pieces, the set has fewer bits than many cobalt sets
- Hex shank limits use to impact drivers and compatible chucks
- Compact 1.1 lb case suggests a smaller, job-site focused assortment
A titanium nitride coating makes these bits last 2.5 times longer than uncoated ones, so they can handle repeated drilling in tough materials without wearing out quickly. This durability is key for tradespeople who rely on an impact driver to punch holes in metal, wood, or plastic on the job. The geometry of its 135-degree split point allows for faster starts and less walking, which saves time when drilling on curved or uneven surfaces. It’s a focused set for mechanics or installers who prioritize long-lasting performance and efficient starts over having a wide range of sizes.
With 14 pieces, this is a compact, job-site set rather than a comprehensive workshop collection. For drilling exclusively in hardened metals with a standard drill press or cordless drill, a dedicated cobalt set like the **Bosch CO14B** offers a different approach with a traditional round shank. The Makita’s brilliance is its impact rating; it turns your impact driver into a capable metal drill, saving you from switching tools. Just know you’re buying a specialized, hard-wearing solution, not a full size library.
OSTTE M35 Cobalt TiAlN Drill Bit Set
What We Like
- TiAlN coating for extreme hardness and heat resistance
- Self-centering bullet point tip for reduced wandering
- M35 cobalt alloy maintains edge under high temperatures
- Organized case with laser-etched size labels
Trade-offs
- Smaller bits (1/16" to 7/64") use a standard, not bullet, tip
- 14-piece set has fewer total bits than some 29-piece competitors
- Bullet point design is most beneficial on larger hole sizes
The TiAlN coating is the star here, pushing surface hardness to 89HRC and offering a multi-fold increase in usable life over standard bits. That coating, paired with the M35 cobalt steel, means these bits can take the heat and stay sharp when working on hardened metal or stainless steel. The sharp, self-centering bullet point tip on the larger sizes is what makes this set stand out for precision; it bites in fast with less pressure and reduces wandering, so you get cleaner, more accurate holes with less burr. This is the set for a fabricator or serious DIYer who needs to drill exact holes in tough materials without constantly resharpening or replacing bits.
Note that bits under 1/8-inch use a standard tip, so you don’t get the bullet point’s self-centering advantage for pilot holes in your toughest projects. If your work demands a comprehensive set of exclusively bullet-point bits in finer increments, you might look at a larger kit like the **Milwaukee Red Helix**. But for the core sizes you’ll use most on hardened stock, the OSTTE set’s combination of advanced coating and precision point engineering delivers a focused, long-lasting performance that justifies its premium positioning.
RCINDUS M35 Cobalt Drill Bit Pack
What We Like
- Large 20-piece pack of a single size
- M35 cobalt construction for hardened metals
- 135° split-point prevents walking on hard surfaces
- Comes in a plastic storage case
Trade-offs
- Only one drill bit diameter (3/16 inch) included
- Lacks the size range of a multi-piece set
- Case design is basic for bulk storage
Twenty identical M35 cobalt bits in a single pack makes this a bulk supply solution. For a contractor or shop that burns through 3/16-inch bits drilling stainless steel or hardened steel, this pack means you can swap in a fresh, sharp bit without halting the job to hunt for a replacement. Its 135-degree split-point geometry helps the bit bite right where you want it on curved or hard surfaces. Factory-direct control over the M35 material suggests a focus on consistent hardness. This is strictly for the user who needs depth in one specific size, not variety.
The clear trade-off is the lack of any other sizes. You’re getting efficiency and redundancy for one common task, not versatility. For a comprehensive workshop set covering a range of holes, a kit like the Drill America DWD29J-CO-PC with 29 sizes is the logical alternative. The RCINDUS pack serves a specific, high-wear scenario perfectly, but it demands you already own a broader set for other drilling needs.
Product photos
Bosch TI5IM Impact Tough Drill Bit Set
What We Like
- Impact-rated shank for high-torque drill/drivers
- Titanium coating reduces friction and wear
- No skate tip design for accurate starts
- Long flutes for effective chip removal
Trade-offs
- Only 5 pieces limits hole size range
- Short 5.2-inch length restricts deep drilling
- Set lacks a storage case for organization
An impact-rated shank means these bits are built to handle the hammering action and high torque of modern cordless impact drivers. This is a serious advantage when drilling into hardened metal where other bits snap. The titanium nitride coating isn’t just for looks; it significantly reduces friction, so the bit stays cooler and cuts longer in heavy-gauge and high-carbon steel. This set is for the mechanic or metal fabricator who needs to make precise, clean holes in tough materials with an impact driver. They can rely on the no-skate tip to stay on target and the long flutes to clear stubborn chips.
The clear trade-off is in the limited scope. With only five bits, you’re covered for common fastener pilot holes but not for a wide range of fabrication tasks. For a more comprehensive kit dedicated to a drill press or standard drill, a larger cobalt set like the Bosch CO14B offers many more sizes. The Bosch TI5IM excels in its specific, rugged niche: turning your impact driver into a capable metal drilling tool without the bit failure that usually comes with that job.
Product photos
How We Evaluated Drill Bits For Hardened Metal
Our evaluation focused on researching manufacturer specifications, materials science, and patterns in owner experiences. We prioritized three key criteria: the bit material and its ability to withstand heat and abrasion, the point geometry for accurate and efficient starts, and the overall set composition for practical workshop use. We examined detailed specifications for cobalt content, coatings like TiN or TiAlN, and whether bits were rated for use in high-torque impact drivers.
Our comparison of HSS and cobalt drill bits confirms why HSS often falls short for hardened metals, steering our focus toward cobalt and carbide options. We also reviewed the design differences between jobber-length and longer bits, and between standard round shanks and impact-rated hex shanks. Because this was a research-based evaluation, we cannot verify individual claims about exact longevity multipliers, but we relied on consistent reporting across expert round-ups and user reviews to identify reliable performance trends.
What To Look For In Drill Bits For Hardened Metal
Choosing a drill bit for hardened steel or stainless steel requires paying attention to the alloy, the tip design, and the tool you’ll be using. A bit that works great in a drill press might fail in a handheld impact driver.
Focus on the core material (cobalt is standard; carbide is for extreme hardness), point geometry to prevent “walking,” and shank compatibility with your drill or driver. A good set for hardened metal should offer heat resistance first and foremost.
Material And Coating
The bit’s material is the most critical factor. For hardened metals, you generally move beyond standard High-Speed Steel (HSS). Cobalt steel alloys, often labeled M35 (with 5% cobalt) or M42 (with 8% cobalt), are the workhorse choice.
They retain their cutting edge at the high temperatures generated by drilling hard metals. Some bits add a surface coating like Titanium Nitride (TiN) or Titanium Aluminum Nitride (TiAlN) for extra hardness and reduced friction. For the absolute hardest materials, like hardened tool steel, solid carbide drill bits are the specialist’s choice, though they are more brittle and expensive.
Point Geometry
The shape of the drill point determines how accurately it starts a hole and how efficiently it cuts. A 135-degree split point is common in cobalt drill bits for metal; the split helps the bit ‘bite’ immediately, reducing the chance it will skate or ‘walk’ across a hard surface. Some specialized bits feature a self-centering bullet point for even greater precision on larger holes, which is ideal for a stable setup on a drill press. A standard point with a wider angle is more prone to wandering on hardened surfaces.
Shank Type & Set Composition
Consider what tool you’ll use. A standard round shank fits any drill chuck. A 1/4-inch hex shank is designed for quick-change chucks, particularly in impact drivers, and these bits must be explicitly rated for impact use to handle the higher torque. When evaluating a set, look beyond the piece count. Check if the included sizes (e.g., 1/16-inch to 1/2-inch) match your common tasks. A bulky case might be fine for a shop but impractical for a service tech’s pouch.
- Verify the shank type matches your drill or impact driver’s chuck.
- Look for clear size markings on the bits or in a labeled case for quick selection.
- Consider if you need jobber-length bits for most work or longer bits for deeper holes.
For most DIYers and pros working on hardened steel, a cobalt bit set with a split point offers the best combination of performance and value.
Drill Bits For Hardened Metal Compared
For a quick glance at how our picks compare in material, key features, and best-use cases, see the table below.
| Product | Material/Coating | Point Angle/Design | Piece Count |
|---|---|---|---|
| Bosch CO14B Cobalt Drill Bit Set | M42 alloy with 8% cobalt | Surface-hardened tip | 14-piece set |
| IRWIN M35 Cobalt Drill Bit Set | M35 cobalt alloy steel | 135-degree split point | 29-Piece |
| Makita Impact Gold Titanium Drill Bit Set | Titanium nitride (TiN) | 135 degree split point | 14 pieces |
| OSTTE M35 Cobalt TiAlN Drill Bit Set | M35 cobalt steel with 5% cobalt, TiAlN | Precision bullet point tip, 135° split | 14 pieces |
| RCINDUS M35 Cobalt Drill Bit Pack | M35 Cobalt HSS (5% Cobalt) | 135 degree split-point | 20 pieces |
| Bosch TI5IM Impact Tough Drill Bit Set | Titanium Nitride | No skate tip | 5 pieces |
Frequently Asked Questions
What brand of drill bit is best for hardened steel?
There is no single “best” brand, as different manufacturers excel with specific material formulas or set configurations. Our research points to brands like Bosch, IRWIN, and specialized makers of cobalt or carbide drill bits as consistently reliable for hardened steel. The best choice depends more on the bit’s cobalt content (M35 or M42), its point geometry, and whether it meets your specific need for heat resistance or impact-driver compatibility.
What is the best drill bit for very hard metal?
For very hard metal like hardened tool steel or stainless steel, cobalt drill bits for hardened steel are the most common and effective choice. For the hardest applications, such as materials with a very high Rockwell C hardness, solid carbide drill bits are necessary, though they require careful, rigid use to prevent breaking. The choice between them hinges on the exact material hardness and your drilling setup.
What type of drill bit is best for drilling through hardened steel?
A cobalt steel drill bit is the best general-purpose type for drilling through hardened steel. Within that category, look for bits with a 135-degree split point to prevent walking and a higher cobalt percentage (M42) for greater heat resistance during extended drilling sessions. Coated bits, like those with a TiAlN layer, can offer additional longevity.
What will cut through hardened steel?
Specialized drill bits made from cobalt steel alloys or solid carbide will cut through hardened steel. The cutting action generates intense heat, so the bit material must retain its hardness at high temperatures. For non-drilling tasks, abrasive methods like grinding with a cutoff wheel or using a carbide burr in a rotary tool are alternatives.
Can you use an impact driver to drill hardened steel?
Yes, but you must use drill bits specifically rated for impact drivers, like our “Best Impact Driver Bits” pick, the Makita Impact Gold set. These bits have a 1/4-inch hex shank and are constructed to withstand the jarring hammering action and high torque of an impact driver, which can break standard bits not designed for it.
The Bottom Line
For a durable, heat-resistant set that handles frequent work on stainless steel and cast iron, the Bosch CO14B Cobalt Drill Bit Set is our best overall pick. If your budget is tighter or you drill very high volumes, consider the heat-resistant IRWIN M35 Cobalt Drill Bit Set. For mechanics who live with an impact driver in hand, the Makita Impact Gold Titanium Drill Bit Set is the clear choice.
When selecting bits for hardened metal, the core material is non-negotiable. Investing in a quality cobalt or carbide bit made for the task will save you from frustration, broken bits, and ruined workpieces.
