Drill bit Proline 77640 — metal, Ø 4 mm, length 220 mm, 1 pc

Proline 77640 metal drill bit, single piece with 4 mm diameter and 220 mm overall length. Manufactured from refined high-speed steel (HSS) and fully ground for straightness and dimensional accuracy, this long-reach drill is designed for drilling steel, non-ferrous metals and plastics. The 135° point angle with chamfering adjustment reduces walking on start and speeds up penetration, making it suitable for use with standard corded or cordless drills and drill presses when through-holes or maintenance access are required.

Advantages

The fully ground flute and refined HSS construction provide high concentricity and durability, helping to maintain hole quality over repeated use. The 135° point angle with chamfering adjustment improves centering and reduces the need for pilot holes, while the extra-long 220 mm overall length enables access to recessed or deep workpieces. Supplied as a single piece, the bit is suitable for one-off jobs or for keeping a specific long-reach size on hand.

Suitable for

• Drilling through-holes in steel and non-ferrous metals
• Maintenance and repair tasks requiring long-reach access
• Light fabrication and metalworking where precise straight holes are needed
• Drilling plastics and non-structural materials

Key specifications

• Material: refined high-speed steel (HSS)
• Diameter: 4 mm
• Overall length: 220 mm
• Point angle: 135° with chamfering adjustment
• Fully ground for improved straightness and hole accuracy
• Suitable for use in drill presses and hand-held drills

How to use

Mark the drilling position and, if needed, use a center punch to reduce wandering. Select an appropriate spindle speed for the 4 mm HSS bit and the material being drilled (higher speeds for non-ferrous metals and plastics, moderate speeds for steel). Secure the workpiece and clamp it to prevent movement. Use cutting fluid or coolant when drilling steel to prolong bit life and improve chip evacuation. Apply steady pressure and allow the bit to cut without excessive force; withdraw occasionally to clear chips when drilling deep holes.

Usage recommendations

For best results, use a pilot hole or spot-drill when precise location is critical, and maintain recommended cutting speeds and lubrication for the material. Store the bit in its case to protect the cutting edges when not in use.