Best Drill Bits for Thick Metal: Top M35 Cobalt and Titanium-Coated Sets
Thick metal drilling demands tools that resist heat, stay sharp, and deliver clean holes. The five picks below blend cobalt alloys (M35 or M42) with advanced coatings like Titanium Nitride (TiN) or Titanium Aluminum Nitride (TiAlN) to extend life and reduce wandering in steel, stainless steel, cast iron, and other hard metals. Each kit is evaluated for edge retention, ease of use, and size range to help professionals and DIYers choose the right set for automotive, fabrication, and heavy-duty projects. Compare material, coatings, and features to guide your purchase.
| Product | Core / Coating | Best For Thick Metal | Set Size |
|---|---|---|---|
| DEWALT DW1361 Titanium Nitride Drill Bits | Titanium Nitride coating; Pilot Point | General metal and thick metal drilling | 21-Piece |
| Bosch CO14B Cobalt M42 Drill Bits | Cobalt M42 alloy | Hardened metal and stainless steel | 14-Piece |
| Crosstar M35 Cobalt Drill Bit Set | M35 cobalt; TiAlN coating | Hardened steel and stainless steel | 21-Piece |
| M35 cobalt | Wide-range heavy-duty metal drilling | 99-Piece | |
| WildBossy M35 Cobalt Drill Bit Set (20Pcs) | M35 cobalt; Ti coating | Highly hardened metal and deep holes | 20-Piece |
DEWALT DW1361 Titanium Nitride Drill Bits
DEWALT’s 21-piece DW1361 set emphasizes durability and precision for metal work. The titanium nitride coating reduces friction, extending bit life under high-speed metal drilling. A Pilot Point design helps start holes on contact, producing cleaner entries and reducing wander on tough surfaces. The bits feature no-spin shanks to ease chuck changes and minimize deflection during aggressive cuts. This combination is particularly effective when drilling through thick steel and iron where edge wear and heat buildup are common concerns. The kit covers a broad range of standard sizes for common metal applications.
- Titanium Nitride coating for longer life
- Pilot Point design for cleaner holes and easier starts
- No spin shanks for smoother, faster changes
When using on thick metal, maintain steady cutting speed and consider lubrication or coolant to extract heat and maximize edge retention across multiple passes.
Bosch CO14B Cobalt M42 Drill Bits
Bosch CO14B brings Cobalt M42 alloy to the fore, delivering exceptional wear resistance for hardened metals. The set is designed for stainless steel, cast iron, titanium, and other tough alloys encountered in metal fabrication and automotive work. The 8% cobalt content translates to significantly longer life under high heat, while the three-flat shank improves torque transfer and reduces cam-out. This combination makes CO14B well suited for drilling thick metal sections where consistent performance and longevity matter more than raw speed. The included case helps with organization and transport on job sites.
- Cobalt M42 alloy for high heat resistance
- 8% cobalt content; longer life vs standard bits
- Three-flat shank for secure torque transfer
For thick metal, use appropriate drill speeds and gradual pecking to manage chip removal and heat, maximizing the life of these high-hardness bits.
Crosstar M35 Cobalt Drill Bit Set (TiAlN, 21Pcs)
The Crosstar M35 set is built for hardened metal and stainless steel with a TiAlN coating that enhances heat resistance and reduces friction. The bit design employs a 3-flute configuration for faster chip removal and less clogging in deep holes, making it suitable for automotive projects and heavy-duty fabrication. Its 5% cobalt core provides excellent hardness, helping maintain sharpness through repeated passes in tough alloys. A self-centering 135-degree tip minimizes wandering and accelerates drilling with minimal pilot holes.
- M35 cobalt alloy with 5% cobalt core
- TiAlN coating extends life under heat
- Triple-flute design for efficient chip removal
When drilling thick metal, pair these bits with steady feeds and consider lubrication to further improve hole quality and extend tool life during long sessions.
Sinyeenglon Cobalt Drill Bit Set (99Pcs)
The Sinyeenglon 99-piece kit provides an extensive range of M35 cobalt bits for hardened metal drilling. The material offers high hardness and wear resistance, with a 67 HRC rating described in product notes, enabling faster cutting in stainless steel, cast iron, zinc alloys, and other tough metals. The full grinding process enhances wear resistance and edge retention. The kit arrives in a sturdy plastic storage case, helping users keep sizes organized for quick access on demanding jobs or in shop environments.
- M35 cobalt with strong wear resistance
- Hardness up to 67 HRC; full grinding process
- Large 99-piece assortment in a sturdy case
For thick-metal work, rely on the wide size range to select the closest pilot sizes and then progress to larger diameters as needed, maintaining steady feeds to preserve tool life.
WildBossy M35 Cobalt Drill Bit Set (20Pcs)
The WildBossy 20-piece set targets tough metals with a 5% M35 cobalt composition, offering notably long life compared with standard HSS bits. Sizes range from 1/16″ to 1/2″, covering common needs for thick-metal drilling across automotive, HVAC, and fabrication tasks. The bits feature Ti surface treatment and a 135-degree self-centering point to minimize wandering, while the 3-flat shank improves grip and reduces slipping in high-torque applications. These features collectively support reliable deep-hole drilling in hardened alloys.
- 5% cobalt alloy; long wear life
- Sizes from 1/16″ to 1/2″
- 135° self-centering tip; 3-flat shank
For best results on very thick metal, use proper feeds and speeds, avoid overheating, and consider stepping up in diameter gradually to reduce stress on the bit during deep drilling.
Buying Guide
Key purchase considerations for drilling thick metal include material and coating, set range, shank design, point geometry, and storage. Coatings such as TiN and TiAlN reduce friction and heat buildup, extending bit life under demanding conditions. Cobalt alloys (M35 or M42) deliver superior hardness and wear resistance compared with standard high-speed steel, making them essential for stainless steel, cast iron, and other tough materials. A broader size range helps handle varied hole diameters without swapping bits mid-project. Look for sets with organized storage and secure shanks to minimize wobble and improve accuracy in deep holes.
Material and coating decisions create different performance profiles. TiN-coated bits like DEWALT DW1361 excel in metal with cleaner starts, while TiAlN-coated options such as Crosstar provide extra heat resistance for prolonged use in hard alloys. M42 cobalt (Bosch CO14B) offers maximum durability under high temperatures, particularly in hardened steel. For very large or precise task lists, Sinyeenglon’s 99-piece kit covers a wider range, but the extra bits may be unnecessary for smaller jobs.
Hole quality and usability hinge on tip geometry and shank design. Self-centering 135-degree tips (as seen in Crosstar and WildBossy) reduce wandering and speed up entry into metals. Pilot Point tips (DEWALT) further promote clean starts, especially when drilling into thicker materials. Three-flat shanks (Bosch CO14B and some Crosstar sets) improve torque transfer and reduce bit slippage in high-torque drilling. When drilling thick metal, maintain steady feeds, consider lubrication, and choose a kit that aligns with your typical material and hole sizes to maximize long-term efficiency and bit life.
| Aspect | Why It Matters | Best Examples |
|---|---|---|
| Coating & Material | Reduces friction and heat, extends life in hardened metals | TiN (DEWALT), TiAlN (Crosstar), M42 cobalt (Bosch), M35 cobalt (Sinyeenglon/WildBossy) |
| Set Size | Broader selections cover multiple hole sizes without changes | 99Pcs Sinyeenglon, 21Pcs Crosstar/WildBossy, 14Pcs Bosch |
| Tip Geometry | Prevents walking and improves entry into thick metal | Pilot Point (DEWALT), 135° self-centering (Crosstar/WildBossy) |
| Shank Design | Higher torque transfer; reduces slip in the chuck | Three-flat shank (Bosch), standard with others |
Selecting the right drill bit set for thick metal depends on the intended materials, typical hole sizes, and how often you expect to drill through hardened alloys. For routine work, a TiN-coated, pilot-point set with a moderate range may be sufficient. For high-heat, high-hardness environments, a full M35/M42 cobalt set with TiAlN coating and a robust case can maximize life and reduce downtime. Consider how you balance initial cost, storage, and the potential need for rare sizes when choosing among these five options.