BOSCH CO14B 14-Piece Cobalt M42 Metal Drill Bit Set: Professional-Grade Drilling Power for the Toughest Materials

When we first unboxed the BOSCH CO14B 14-Piece Cobalt M42 Drill Bit Set, we knew we had something special in our hands. After putting these bits through rigorous testing on various hard metals—from stainless steel to cast iron—we can confidently say this set delivers the precision and durability that professionals and serious DIYers demand.

Price: $39.29
(as of May 01, 2026 04:47:29 UTC – Details)

Why the Bosch CO14B Outperforms Standard Drill Bits

During our hands-on testing, the difference between these cobalt bits and standard high-speed steel became immediately apparent. The M42 cobalt construction isn’t just marketing speak—we noticed significantly less heat buildup when drilling through 1/4-inch stainless steel plates, and the bits maintained their sharp cutting edges even after multiple applications.

The three-flat shank design proved invaluable during our testing phase. Unlike traditional round shanks that can slip under high torque, these bits locked firmly into our drill chuck, eliminating the frustration of bit slippage that we’ve experienced with lesser quality sets.

What’s Inside the BOSCH CO14B Set

The 14-piece assortment covers the most commonly needed sizes for metalworking projects:

• 1/16-inch bit (1 piece)
• 5/64-inch bit (1 piece)
• 3/32-inch bit (1 piece)
• 7/64-inch bit (1 piece)
• 1/8-inch bit (2 pieces)
• 9/64-inch bit (1 piece)
• 5/32-inch bit (1 piece)
• 11/64-inch bit (1 piece)
• 3/16-inch bit (2 pieces)
• 13/64-inch bit (1 piece)
• 7/32-inch bit (1 piece)
• 1/4-inch bit (2 pieces)

We particularly appreciated that Bosch included duplicate bits in the most commonly used sizes (1/8-inch, 3/16-inch, and 1/4-inch), as these tend to wear out faster with regular use.

Our Real-World Testing Experience

We subjected these cobalt bits to a variety of challenging materials to see how they truly performed:

Stainless Steel Performance

Drilling through 304 stainless steel can be a nightmare with inferior bits. We tested the 3/16-inch bit on a stainless steel kitchen backsplash mounting project, and the results impressed us. With proper cutting fluid and moderate pressure, the bit penetrated smoothly without chattering or wandering. The precision 135-degree split point started exactly where we marked, eliminating the need for center punching on most applications.

Cast Iron Applications

Working with cast iron requires bits that can handle abrasive material without dulling quickly. When we drilled mounting holes in a vintage cast iron machine base, the cobalt construction proved its worth. After creating over twenty holes, we examined the bit under magnification and found minimal wear on the cutting edges—a testament to the M42 cobalt’s exceptional hardness.

Titanium and Light-Gauge Metal

Though we primarily used these for heavier materials, we also tested them on 16-gauge aluminum and found they performed beautifully. The sharp cutting edges produced clean holes without grabbing or creating burrs. For titanium drilling (a notoriously difficult material), the 1/8-inch bit handled Grade 2 titanium sheet with appropriate cutting speeds and lubrication.

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Key Features That Make a Difference

M42 Cobalt Construction

The 8% cobalt content in these bits provides exceptional heat resistance and hardness. During extended drilling sessions, we measured surface temperatures and found these bits stayed noticeably cooler than conventional HSS bits, which translates to longer bit life and faster drilling speeds.

Three-Flat Shank Design

This feature became one of our favorites during testing. The three flat surfaces on the shank create a positive grip that prevents slipping, especially important when drilling through tough materials that create high torque resistance. We never experienced a single instance of the bit spinning in the chuck, even without over-tightening.

135-Degree Split Point

The precision-ground split point geometry serves two critical functions we observed: it starts on contact without walking across the surface, and it generates less heat and friction than standard 118-degree points. This design feature particularly shined when working on curved or angled surfaces where bit wandering typically causes problems.

Included Storage Case

The molded case isn’t just a throwaway container—it’s a genuinely useful organizational tool. Each bit has its designated slot, clearly marked with size information. After months of use in our workshop, the case has protected the bits from damage and kept them organized. The transparent lid lets us quickly identify the size we need without opening the case.

What We Loved Most

After extensive use, several aspects of this drill bit set stood out:

**Longevity**: Even after dozens of holes in hardened materials, the cutting edges remained sharp. We compared wear patterns against premium individual bits costing significantly more and found comparable performance.

**Versatility**: While marketed for metal applications, we found these bits excelled in wood and plastic as well, making them a truly universal option for the workshop.

**Professional Results**: The clean, precise holes these bits produce rival those from industrial-grade equipment. Burr formation was minimal, and hole diameter accuracy remained consistent throughout our testing.

**Value Proposition**: Considering the quality and performance, this 14-piece set costs less than purchasing just three or four premium individual cobalt bits from other manufacturers.

Honest Assessment: What Could Be Better

In the interest of providing a balanced review, we did identify a few minor considerations:

The smallest bits (1/16-inch and 5/64-inch) require careful handling, as the cobalt material, while hard, is also somewhat brittle. We recommend avoiding side pressure and ensuring proper chuck alignment to prevent breakage.

For ultra-precision applications requiring tolerances within 0.001 inches, you might need to finish with a reamer, though this is true of virtually all twist drills and not specific to this set.

The case, while functional, lacks a locking mechanism. If you’re transporting the set in a toolbox where it might get jostled, you’ll want to secure it with a rubber band or keep it in a protected compartment.

Customer Reviews Analysis: What Other Users Are Saying

We didn’t just rely on our own testing—we analyzed hundreds of customer reviews to see how the BOSCH CO14B 14-Pc Cobalt M42 Drill Bit Set for Metal & Steel performs in diverse real-world applications.

Professional fabricators consistently praise the set’s durability, with several reviewers reporting successful drilling through materials like hardened steel bolts and thick stainless steel plates. One HVAC technician mentioned using the set daily for three years with minimal bit replacement needed.

Home workshop users particularly appreciate the value, noting that the performance rivals individual bits costing $15-20 each