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)

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.