Twist drill bit set Irwin 10502519 — 3.5 mm diameter, 10 pieces

Irwin 10502519 is a set of ten 3.5 mm twist drill bits designed for general drilling in workshop and repair environments. Each bit is made from high-speed steel with cobalt alloy to increase heat and abrasion resistance, and the 135° split point reduces walking and starts holes cleanly. Packaged as a 10-piece kit, the set supports repetitive tasks where consistent hole size and bit durability are required.

Advantages

The cobalt-enhanced HSS composition (5% cobalt) provides higher resistance to heat and wear compared with standard HSS, extending tool life during demanding jobs. A heavy-duty web construction increases strength and reduces the risk of breakage when drilling into tougher materials. The 135° split point geometry improves centring and reduces the need for pilot holes, while manufacturing to DIN 338 standards ensures consistent dimensions and performance.

Suitable for

• Drilling small, accurate holes in metal components and assemblies
• Repair, maintenance, and fabrication tasks with handheld or machine-mounted drills
• Working with hardened or heat-treated steels and abrasive alloys

Key specifications

• Diameter: 3.5 mm
• Quantity: 10 pieces
• Material: high-speed steel with 5% cobalt
• Point angle: 135° split point for reduced walking
• Construction: heavy-duty web for added strength
• Manufacturing standard: produced to DIN 338 dimensional and performance guidelines

How to use

Select the 3.5 mm bit from the set and secure it in the drill chuck with correct alignment. For best results when drilling metal, mark the hole position and, if needed, create a small centre punch indentation to help initial tracking. Use steady feed pressure and maintain a moderate to low drilling speed when working with hardened or abrasive alloys; increase speed only when drilling softer materials. Periodically clear chips from the hole and apply cutting fluid or coolant when drilling steel to reduce heat build-up and prolong bit life.

Usage recommendations

For prolonged bit life when drilling hardened or heat-treated metals, use cutting fluid, maintain appropriate drill speeds, and avoid excessive axial force. When starting holes in thin or slippery surfaces, use a centre punch or a starter pilot to prevent walking. Store the bits in their original case to protect cutting edges and ensure consistent performance.