Drill bits Proline 78041K, metal, Ø4.1 mm, length 75 mm, 2 pcs

Proline 78041K is a set of two metal drill bits with a 4.1 mm diameter and 75 mm overall length. Manufactured from high-speed steel with 5% cobalt (HSS-Co), these bits are ground entirely to ensure precision and straightness of holes. The 135° point angle with chamfering adjustment improves centring and allows fast, cleaner penetration in high-alloy and difficult-to-machine metals; the bits are suitable for use in handheld drills and drill presses and are supplied in a blister pack containing two identical pieces.

Advantages

The HSS-Co composition provides elevated temperature resistance and extended tool life when drilling hard and heat-prone materials. A 135° split point reduces walking at the drill start and lowers the need for pilot holes, while full grinding of the flute and body ensures accurate hole straightness and repeatable results. The 75 mm overall length offers sufficient reach for common workshop and repair tasks without compromising stability.

Suitable for

• Drilling high-alloy steels and stainless steels
• Working with titanium and acid-resistant metals
• Light- to medium-duty metal repairs and assembly
• Use in handheld drills and drill presses

Key specifications

• Diameter: 4.1 mm
• Overall length: 75 mm
• Material: high-speed steel with 5% cobalt (HSS-Co)
• Point angle: 135° with chamfering adjustment
• Manufacturing: fully ground flutes and body for accuracy
• Pack quantity: 2 pieces

How to use

Secure the workpiece and mark the drilling position. Use a centre punch for best results if necessary. Fit the 4.1 mm Proline bit into a suitably rated drill chuck, ensure the chuck is tightened, and select an appropriate cutting speed for the workpiece material—lower speeds for stainless and high-alloy steels. Apply steady pressure without excessive force and periodically withdraw the bit to clear chips and reduce heat buildup. For deeper holes, cool with cutting fluid to maintain tool life and hole quality.

Usage recommendations

Use cutting fluid or coolant when drilling high-alloy or stainless steels to reduce heat and extend drill life. Start at reduced speed to avoid workpiece damage, and check bit sharpness regularly; replace when wear affects hole accuracy. Store the bits in their blister pack or a dry tool organiser to prevent corrosion and protect the cutting edges.