Bosch CO21 21-piece cobalt drill bit set in a clear plastic case with labeled packaging highlighting features like "Hard Core Cobalt," "4x Life," and "No Skate Tip," suitable for stainless steel and other metals.
Close-up of twist drill bits arranged by size, showcasing the helical flute design and cylindrical shanks used for drilling in metal, wood, and plastic.
Visual icons representing wood, plastic, and metal materials with the heading "Best for," indicating the drill bit set’s compatibility across multiple surfaces.
Bosch CO21 21-piece cobalt drill bit set in a clear plastic case with labeled packaging highlighting features like "Hard Core Cobalt," "4x Life," and "No Skate Tip," suitable for stainless steel and other metals.
Bosch CO21 21-piece cobalt drill bit set in a clear plastic case with labeled packaging highlighting features like "Hard Core Cobalt," "4x Life," and "No Skate Tip," suitable for stainless steel and other metals.
Close-up of twist drill bits arranged by size, showcasing the helical flute design and cylindrical shanks used for drilling in metal, wood, and plastic.
Visual icons representing wood, plastic, and metal materials with the heading "Best for," indicating the drill bit set’s compatibility across multiple surfaces.
Bosch CO21 21-piece cobalt drill bit set in a clear plastic case with labeled packaging highlighting features like "Hard Core Cobalt," "4x Life," and "No Skate Tip," suitable for stainless steel and other metals.
BOSCH

Bosch Drill Bit Set CO21 21 Piece Cobalt Twist Metal (1/16 to 1/2 Inch 135 Degree Split Point Three Flat Shank Stainless Steel Drilling)

In stock
SKU: CO21
$52.49 USD

Description

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Bosch CO21 21-Piece Cobalt Twist Drill Bit Set with Storage Case

The Bosch CO21 21-Piece Cobalt Drill Bit Set is an industrial metal-drilling accessory kit engineered for penetration through tough substrates including stainless steel, cast iron, titanium alloys, and structural aluminum. Manufactured from high-speed steel with a cobalt alloy formulation that withstands elevated friction temperatures, these bits provide up to four times the service life of standard HSS bits. Featuring 135-degree split-point tips that eliminate bit walking and three-flat shanks on sizes 3/16-inch and larger to prevent chuck slipping, this fractional set covers hole diameters from 1/16-inch to 1/2-inch inside a rugged storage case.

Best Used For:

  • Stainless Steel & Structural Alloy Drilling: Boring clean, precise mounting holes in stainless steel sheet, structural tubing, and high-tensile iron plates.
  • Cast Iron & High-Temperature Metal Machining: Drilling through abrasive cast iron blocks, titanium components, and dense motor housings without thermal dulled tips.
  • Sheet Metal & Non-Ferrous Shearing: Producing burr-free pilot holes in aluminum plate, brass bar stock, structural steel studs, and thick plastic panels.

Key Performance & Safety Features

  • Cobalt High-Speed Steel Alloy Construction: Formulated metal chemistry retains edge hardness under high drilling friction heat for extended bit life.
  • 135-Degree Split-Point Tip Geometry: Self-centering tip design engages workpieces immediately to eliminate bit skating without center punches.
  • Three-Flat Shank Design (3/16 In. & Larger): Precision-ground shank flats lock securely into three-jaw drill chucks to stop bit slippage under high torque loads.
  • Laser-Etched Diameter Markings: Permanent laser markings on bit shanks ensure instant size identification and organization inside tool cases.
  • High-Temperature Thermal Endurance: Withstands intense heat buildup generated when dry-drilling hard stainless steel and titanium alloys.
  • Heavy-Duty Hard Index Storage Case: Custom molded bit organizer keeps all 21 fractional drill bits organized and protected during transport.

What's Included

  • (2) 1/16 In. Cobalt Twist Drill Bits
  • (2) 5/64 In. Cobalt Twist Drill Bits
  • (1) 3/32 In. Cobalt Twist Drill Bit
  • (1) 7/64 In. Cobalt Twist Drill Bit
  • (2) 1/8 In. Cobalt Twist Drill Bits
  • (1) 9/64 In. Cobalt Twist Drill Bit
  • (1) 5/32 In. Cobalt Twist Drill Bit
  • (1) 11/64 In. Cobalt Twist Drill Bit
  • (2) 3/16 In. Cobalt Twist Drill Bits
  • (1) 13/64 In. Cobalt Twist Drill Bit
  • (1) 7/32 In. Cobalt Twist Drill Bit
  • (1) 15/64 In. Cobalt Twist Drill Bit
  • (2) 1/4 In. Cobalt Twist Drill Bits
  • (1) 5/16 In. Cobalt Twist Drill Bit
  • (1) 3/8 In. Cobalt Twist Drill Bit
  • (1) 1/2 In. Cobalt Twist Drill Bit
  • (1) Heavy-Duty Storage Case

Technical Specifications

Brand / Manufacturer Bosch
Model / Part Number CO21
Total Piece Count Included 21 Pieces
Drill Bit Material Composition Cobalt Steel Alloy
Size Capacity Diameter Range 0.0625 in. to 0.50 in. (1/16 in. to 1/2 in.)
Drill Point Angle Geometry 135° Split-Point Tip
Shank Interface Configuration Three-Flat Shank (3/16 in. and larger) / Straight Round Shank (under 3/16 in.)
Performance Life Rating Up to 4X Life vs. Standard High-Speed Steel Bits
Diameter Size Identification Laser-Etched Markings on Shank
Primary Substrate Application Stainless Steel, Cast Iron, Titanium, Aluminum, Wood, Plastic
Pro-Tip: Use cutting fluid or tapping oil and run drill motors at low RPM settings when drilling stainless steel; controlling rotational speed prevents work-hardening the metal while preserving the sharp cobalt split-point edge.