Drill bits Proline 78042K, metal, Ø 4.2 mm, length 75 mm, 2 pcs

Proline 78042K drill bits for metal are a set of two high-precision HSS-Co bits with a diameter of 4.2 mm and overall length 75 mm. Designed for drilling metal sheets and thin-walled parts, these straight-shank bits fit handheld drills and drill presses. The 135° point angle with chamfering adjustment allows faster penetration and reduced walking at the start, while the fully ground flutes ensure accurate, straight holes. Made from high-class high-speed steel with 5% cobalt, the bits offer improved heat resistance and durability when working with demanding alloys.

Advantages

The 135° point geometry combined with chamfering reduces the need for center punching and improves centring on metal surfaces. Cobalt-enriched HSS composition increases resistance to elevated temperatures, extending tool life during prolonged cutting. Full grinding production delivers consistent diameter accuracy and rectilinearity, which is important for precision fastening and maintenance tasks. The straight shank design provides compatibility with a wide range of chucks and drill holders.

Suitable for

• Drilling high-alloy and stainless steels
• Working with titanium, acid-resistant and creep-resisting steels
• Creating holes in metal sheets and thin-walled components
• General metalworking, assembly and maintenance tasks

Key specifications

• Material: high-speed steel (HSS) with 5% cobalt
• Diameter: 4.2 mm
• Overall length: 75 mm
• Point angle: 135° with chamfering provision
• Manufacturing: fully ground flutes for high accuracy
• Intended materials: high-alloy steels, stainless and acid-resistant steels, titanium, cast iron and other hard-to-machine metals
• Package contents: 2 pieces per blister pack

How to use

Secure the correct drill bit in the chuck of a handheld drill or drill press, ensuring the straight shank is held firmly and runs true. Mark the drilling position and, if necessary, use the chamfering feature or a small pilot mark to improve centring. Select appropriate cutting speed and feed rate for the workpiece material; lower speeds are recommended for hard alloys and stainless steels. Use cutting fluid or coolant when drilling tougher materials to reduce heat build-up and prolong bit life. Withdraw periodically to clear chips and prevent clogging.

Usage recommendations

For best results when drilling stainless or high-alloy steels, use moderate spindle speed, steady feed and a suitable cutting fluid. Replace worn bits to maintain hole quality; the 135° point reduces walking but correct setup and steady pressure remain essential for precision holes.