Drill Bit Set Bosch HSS Twist Drill Bits Ground – high-speed steel, ground flute, individual sizes (Bosch 2608585920)

Bosch HSS Twist Drill Bits Ground are precision high-speed steel twist drills designed for accurate and reliable metal drilling. The bits feature a 135° self-centring split-point tip and precision-ground flutes to reduce wandering and ensure clean hole entry. Manufactured to DIN 338 with Type N flute geometry and a diameter tolerance of h8, these HSS bits suit both hand drills and drill presses and are intended for drilling alloyed and non-alloyed steels, cast iron, non-ferrous metals and hard plastics.

Advantages

The precision-ground geometry and 135° split-point tip provide improved centring and reduced walking on the workpiece, allowing drilling without pre-punching or pilot holes up to 10 mm. Compared with standard chisel-edge HSS drills, these ground bits enable up to 40% faster drilling rates and require up to 50% lower feed pressure. The cylindrical shank matches the drill diameter for secure clamping, while the high-speed steel construction balances hardness and toughness for durable cutting edges in metalworking applications.

Suitable for

• Drilling alloyed and non-alloyed steel
• Working with cast steel, cast iron and sintered iron
• Drilling non-ferrous metals (aluminium, copper, brass)
• Creating holes in hard plastics
• Use in hand-held drills and drill stands/presses

Key specifications

• Material: High-speed steel (HSS)
• Tip angle: 135° self-centring split point
• Flute type: Ground twist flute, Type N
• Tolerance: Diameter tolerance h8
• Shank: Cylindrical, equal to drill diameter
• Standard: Manufactured to DIN 338

How to use

Secure the appropriate-sized Bosch HSS ground twist drill bit in the drill chuck, ensuring the cylindrical shank is clamped firmly and runout is minimised. Select a suitable cutting speed and feed for the workpiece material—lower speeds for harder steels and higher speeds for non-ferrous metals. Begin drilling with steady pressure; the 135° split-point tip allows accurate centring without a pilot hole for diameters up to 10 mm. Use cutting fluid or coolant when drilling steels and cast irons to extend tool life and improve chip evacuation. Periodically withdraw the bit to clear chips and prevent heat build-up.

Usage recommendations

For best results, match cutting speed and feed to material hardness, use appropriate cutting fluid for ferrous metals, and avoid excessive side loads. Replace or resharpen bits when edges become dull to maintain hole quality and drilling efficiency.