A studio photograph of the Bosch CO21B 21-piece cobalt drill bit set in its original retail packaging, featuring a clear-faced plastic case that shows the assorted bits and 10X life branding.
A studio photograph displaying the full 21-piece assortment of gold-colored cobalt M42 twist drill bits, arranged by size from largest to smallest to show the variety of diameters.
A close-up studio photograph of a single cobalt drill bit with callouts identifying the split point on bits 1/8 inch and larger, the surface-hardened tip, thick web-helix design, and the three-flat shank.
An action photograph showing a Bosch cobalt drill bit penetrating a thick metal plate, creating long metal shavings to demonstrate its high-speed material removal.
An action photograph of a cobalt drill bit being used to drill into a clamped metal workpiece, demonstrating the durability of the bit in a workshop setting.
An instructional graphic displaying five materials the bits are best suited for: cast iron, titanium, aluminum, stainless steel, and light-gauge metal.
An action photograph showing a Bosch drill equipped with a cobalt M42 bit drilling into a metal surface covered in shavings, with the storage case visible in the foreground.
A studio photograph of the Bosch CO21B 21-piece cobalt drill bit set in its original retail packaging, featuring a clear-faced plastic case that shows the assorted bits and 10X life branding.
A studio photograph displaying the full 21-piece assortment of gold-colored cobalt M42 twist drill bits, arranged by size from largest to smallest to show the variety of diameters.
A close-up studio photograph of a single cobalt drill bit with callouts identifying the split point on bits 1/8 inch and larger, the surface-hardened tip, thick web-helix design, and the three-flat shank.
An action photograph showing a Bosch cobalt drill bit penetrating a thick metal plate, creating long metal shavings to demonstrate its high-speed material removal.
An action photograph of a cobalt drill bit being used to drill into a clamped metal workpiece, demonstrating the durability of the bit in a workshop setting.
An instructional graphic displaying five materials the bits are best suited for: cast iron, titanium, aluminum, stainless steel, and light-gauge metal.
An action photograph showing a Bosch drill equipped with a cobalt M42 bit drilling into a metal surface covered in shavings, with the storage case visible in the foreground.
BOSCH

Bosch CO21B 21 Piece Cobalt M42 Metal Drill Bit Set for Stainless Steel Cast Iron and Titanium High Heat Resistant 135 Degree Split Point

In stock
SKU: CO21B
$70.79

Description

Unrivaled Durability in Hard Metals: Engineered with 8% Cobalt for 10X Longer Life

The Bosch CO21B 21-Piece Cobalt M42 Drill Bit Set is the definitive choice for professionals facing the toughest drilling challenges. Engineered with an upgraded M42 alloy containing 8% cobalt, these "hard-core" bits are specifically designed to deliver 10X the service life of standard bits while withstanding extreme heat in high-temperature applications. Whether you are drilling through stainless steel, cast iron, or titanium, the thick web-helix design provides superior stability and rapid material removal, ensuring precision and efficiency on every job.

Designed for maximum jobsite performance, these bits feature a specialized 135-degree split point on all sizes 1/8" and larger, allowing for immediate, "no-skate" starts without the need for a center punch. To further increase productivity, bits 3/16" and larger are equipped with a three-flat shank that provides a secure grip in the drill chuck, effectively eliminating bit slippage during high-torque tasks. From light-gauge aluminum to abrasive hardened metals, this comprehensive set provides the specialized tip geometry and heat resistance required for professional-grade results.

Key Features

  • Upgraded M42 Alloy: Formulated with 8% cobalt to provide 10X life versus standard drill bits.
  • Extreme Heat Resistance: Engineered to withstand high-temperature applications for extended periods without dulling.
  • Thick Web-Helix Design: Increases structural stability and provides fast material removal in tough materials.
  • No-Skate Split Point: Bits 1/8" and larger feature a split point for accurate starts without a center punch.
  • Secure Three-Flat Shank: Bits 3/16" and larger feature three flats on the shank to prevent bit slippage in the chuck.
  • Hardened Surface: Specifically designed to penetrate hardened surfaces including stainless steel, titanium, and cast iron.

What's Included

  • (2) 1/16", (2) 5/64", (1) 3/32", (1) 7/64" Cobalt Bits
  • (2) 1/8", (1) 9/64", (1) 5/32", (1) 11/64" Cobalt Bits
  • (2) 3/16", (1) 13/64", (1) 7/32", (1) 15/64" Cobalt Bits
  • (2) 1/4", (1) 5/16", (1) 3/8", (1) 1/2" Cobalt Bits
  • (1) Rugged Storage Case

Specifications

Brand Bosch
Model Number CO21B
Bit Material M42 Cobalt Alloy (8% Cobalt)
Bit Type Twist / Jobber Length
Total Piece Count 21
Tip Geometry 135-Degree Split Point
Shank Design Three-Flat (3/16" and larger)
Weight 1.19 lbs
Compatible Materials Stainless Steel, Cast Iron, Titanium, Aluminum
Product Condition New

Pro-Tip: When drilling into hard metals like stainless steel with cobalt bits, use a slower drill speed and apply steady pressure. This technique, combined with the 8% cobalt alloy, minimizes heat buildup and ensures the longest possible cutting life for your bits.