Twist drill bit Bosch HSS 4.2 mm

The Bosch HSS hex-shank twist drill bit with a 4.2 mm diameter is a precision tool designed for reliable drilling in a range of materials. Machined from high-speed steel and featuring an oxide-coated flute, this single drill bit provides improved wear resistance and consistent material removal. The 1/4-inch hex shank delivers a secure fit in impact drivers and other compatible power tools, while the split-point geometry with a 135° tip enhances centring and reduces walking at the start of drilling. Supplied in a blister pack, the bit is convenient to store and transport for jobsite use or home workshops.

Advantages

The solid HSS construction and precision grinding ensure high hardness and temperature resistance during prolonged drilling operations. The oxide-coated flute reduces friction and wear, extending tool life and maintaining cutting performance. The split-point tip provides active cutting and accurate centring, improving hole quality and minimising the need for pilot holes. The hex shank design secures the bit in chucks and quick-change holders, preventing slippage under torque and making the bit suitable for use with impact-capable drivers.

Suitable for

Key specifications

How to use

Select an appropriate drilling speed and feed rate for the material being worked; lower speeds for harder metals and higher speeds for softer materials. Secure the workpiece and ensure the tool is clamped firmly in a compatible 1/4-inch hex chuck or quick-change holder. Start drilling at low speed to establish the hole and then increase speed as required, applying steady axial pressure. Use cutting fluid or lubrication when drilling metals to reduce heat and extend bit life. Clear chips regularly to avoid clogging the flutes.

Recommendations

For optimal performance when drilling metals, use coolant or cutting oil, avoid excessive lateral forces, and replace the bit if chipping or dulling occurs. The hex shank is suited for impact drivers, but match speed and torque to the material to prevent overheating and premature wear.