Twist drill bit set Irwin 10502508 — 2 pcs, 1.5 mm diameter

Irwin 10502508 — 2 pcs, 1.5 mm diameter is a set of two precision HSS cobalt twist drill bits designed for making small-diameter holes. Each bit has a 1.5 mm cutting diameter and a 40 mm overall length with a cylindrical (straight) shank, manufactured to DIN 338 standards. The bits incorporate 5% cobalt for improved heat and abrasion resistance and a heavy-duty web for enhanced strength. A 135° split point reduces walking and starts drilling immediately, making these bits suitable for demanding drilling tasks in a variety of materials.

Advantages

The 5% cobalt composition increases hardness and thermal stability compared with standard HSS, extending life when drilling alloyed and hardened steels. The heavy-duty web construction adds rigidity and reduces breakage during side loads. The 135° split point improves centering and reduces the need for pilot holes, while the straight shank ensures compatibility with most drill chucks. Manufactured to DIN 338, these bits offer consistent geometry and dimensions for repeatable results.

Suitable for

• Drilling small precision holes in alloyed steel and stainless steel
• Metalworking tasks requiring heat-resistant bits
• Maintenance and repair work with limited access or small-diameter requirements
• Drilling in hard or heat-treated metals where abrasion resistance is needed

Key specifications

• Type: Twist drill bit, HSS with 5% cobalt
• Diameter: 1.5 mm
• Overall length: 40 mm
• Point angle and style: 135° split point
• Shank type: Cylindrical (straight) shank
• Quantity: 2 pieces
• Standards: Manufactured to DIN 338 geometry
• Typical suitable materials: Alloyed steel, stainless steel, general metal

How to use

Secure the cylindrical shank of the 1.5 mm Irwin drill bit in an appropriate drill chuck, ensuring proper concentricity. Mark and, if necessary, center-punch the drilling position to aid the 135° split point in locating the start. Use appropriate cutting speed and feed for small-diameter cobalt HSS bits—moderate speeds for steels and harder alloys and higher speeds for softer metals—while applying steady, even pressure. Use cutting fluid or coolant when drilling alloyed or hardened steels to reduce heat buildup and extend bit life. Withdraw the bit periodically to clear chips when drilling deep holes or when chip evacuation is restricted.

Usage recommendations

For best results when drilling hardened or alloyed steels, use low to moderate spindle speeds, apply suitable coolant, and avoid excessive side loading. Replace the bit if excessive wear or chipping of the cutting edges is visible to maintain hole quality and reduce the risk of breakage.