Twist drill bit Irwin 10502549 — 4.2 mm, single piece

Irwin twist drill bit model 10502549 with a 4.2 mm diameter is a single-piece HSS cobalt twist drill designed for precision drilling in a range of metals. The bit features a 135° split point and a cylindrical shank suitable for use in hand drills and drill presses. Manufactured to DIN 338 standards and produced with 5% cobalt content, this 4.2 mm drill bit is intended for demanding metalworking tasks where improved heat and abrasion resistance is required.

Advantages

The 5% cobalt composition increases heat and wear resistance compared with standard high-speed steel, helping maintain cutting performance at higher temperatures. The heavy-duty web construction improves strength and reduces the risk of breakage during heavy use. The 135° split point reduces bit walking at the start of drilling and enables quicker penetration, while the straight-twist geometry facilitates efficient chip evacuation for stable drilling and clean hole quality.

Suitable for

• Drilling holes in alloyed steel and other metals
• Work on stainless steel where greater abrasion resistance is needed
• Preparation, repair and installation tasks requiring a precise 4.2 mm hole

Key specifications

• Drill type: twist drill bit (single piece)
• Diameter: 4.2 mm
• Overall length: 75 mm
• Material: high-speed steel with 5% cobalt
• Point angle and style: 135° split point
• Shank type: cylindrical
• Standards: manufactured to DIN 338
• Suitable materials: alloyed steel, metal, stainless steel

How to use

Secure the twist drill bit in the chuck of a compatible hand drill or drill press, ensuring the cylindrical shank is fully gripped. Select an appropriate rotational speed and feed rate for the target material; lower speeds are recommended for hardened or stainless steels to reduce heat build-up. Use cutting fluid or coolant when drilling tougher or heat-sensitive metals to extend tool life and improve chip evacuation. Apply steady, even pressure and allow the split point to start the hole before increasing feed to avoid deflection.

Usage recommendations

Use cutting fluid for prolonged drilling in stainless or heat-treated steels, monitor bit temperature during extended operation, and replace the bit if signs of wear or chipping appear to maintain hole accuracy and safety.