Drill bit Bosch HSS-Co 135 7.5 mm x 69 mm — high-speed cobalt twist drill

Bosch HSS-Co 135 7.5 mm x 69 mm is a high-speed cobalt twist drill engineered for precise drilling in harder metals. With a 7.5 mm cutting diameter and 69 mm overall length, this drill bit combines a 135° split-point geometry and a cobalt-enriched high-speed steel composition to provide improved centring, reduced walking and higher heat resistance compared with conventional HSS bits. The construction is tailored to professional and workshop applications where reliable hole quality and extended tool life are required when working with steel and stainless steel.

Advantages

The 135° point angle ensures fast penetration and accurate centring, minimising the need for pilot holes. Cobalt alloy in the cutting material increases temperature tolerance and wear resistance, supporting longer life under high-speed and high-load conditions. The twist-drill geometry provides efficient chip evacuation and stable cutting action, resulting in cleaner holes and consistent performance across a range of metalworking tasks.

Suitable for

• Drilling holes in carbon steel and alloy steel
• Drilling stainless steel and heat-resistant metals
• Professional workshop and metal fabrication tasks
• Repair, maintenance and machinery component machining

Key specifications

• Cutting diameter: 7.5 mm
• Overall length: 69 mm
• Material: high-speed steel with cobalt (HSS-Co)
• Point angle: 135° split point for improved centring
• Geometry: twist drill for efficient chip evacuation
• Intended application: drilling in harder metals including stainless steel

How to use

Secure the workpiece and mark the drilling position. Use an appropriate drill chuck or collet compatible with a 7.5 mm shank, and set the drill press or hand drill to a speed suitable for HSS-Co drills and the material being drilled (lower speeds for stainless steel). Apply steady, even pressure and avoid excessive feed that could overload the bit. Periodically withdraw the drill to clear chips and allow cooling; for continuous or deep drilling use cutting fluid or coolant to reduce heat buildup and extend tool life.

Usage recommendations

For best results when drilling stainless steel or heat-resistant alloys, use low cutting speeds, generous lubrication and moderate feed rates. Inspect the drill bit for wear or chipping before use and replace when cutting performance declines to maintain hole quality and prevent workpiece damage.