Drill bit Proline 7 mm, model 78070K, length 109 mm, metal drill bit, 1 piece

Proline 7 mm metal drill bit with a 109 mm overall length is a single HSS-Co twist drill designed for general-purpose metalworking. The bit features a 135° point angle with chamfering adjustment for reduced walking and faster drilling. Manufactured by full grinding from high-grade high-speed steel with 5% cobalt, this drill bit provides improved heat resistance and dimensional accuracy for clean holes in steels and other hard-to-machine alloys. It is supplied as a single piece in a blister pack suitable for workshop and maintenance use.

Advantages

The combination of HSS with 5% cobalt increases hardness at elevated temperatures and extends cutting life compared with standard HSS bits. A 135° split-point geometry reduces the need for center punching and improves centering on metal surfaces. Fully ground flutes and thinned margins ensure high concentricity and straightness of drilled holes, while the reinforced tip geometry supports drilling into stainless, high-alloy, titanium and heat-resistant steels and cast iron.

Suitable for

• Drilling clean holes in steel, stainless steel and high-alloy metals
• Workshop maintenance and repair tasks using hand drills or drill presses
• Applications that require accurate, straight holes in difficult-to-machine materials

Key specifications

• Diameter: 7 mm
• Overall length: 109 mm
• Material: high-speed steel with 5% cobalt (HSS-Co)
• Point angle: 135° with chamfering/split-point geometry
• Manufacturing: fully ground twist drill for high accuracy
• Suitable materials: high-alloy steels, stainless and acid-resistant steels, titanium, creep-resisting steels and cast iron
• Packaging: single piece in blister pack

How to use

Secure the workpiece and select an appropriate clamping method to prevent movement. Fit the 7 mm drill bit into the chuck of a hand drill or drill press and tighten securely. Use a moderate feed rate and appropriate cutting speed for the material being drilled; when working with stainless or high-alloy steels reduce speed and apply cutting fluid to control temperature and extend tool life. Start drilling at low speed to establish the hole, then maintain steady pressure until the hole is complete. Retract periodically to clear chips when drilling deep holes.

Usage recommendations

For best results when drilling stainless, high-alloy or heat-resistant steels, use cutting fluid and lower spindle speeds to minimize heat buildup. When the surface is prone to walking, a center punch or the split-point geometry will help with accurate positioning. Store the drill bit dry in its blister pack to protect the cutting edges.