Hertel 42091 Cobalt Jobber Drill Bit 8 Mm 135 Degree

Product Description

The HERTEL 42091 is a cobalt jobber length drill bit designed for drilling through hard and abrasive materials including stainless steel, high-alloy steels, and other tough metals. Built from M35 cobalt steel and finished with an oxide and gold coating, the bit resists heat buildup and wear during high-speed drilling operations. It features a 135-degree split point that reduces walking on contact, a two-flute right-hand spiral configuration for chip evacuation, and a straight cylindrical shank for standard drill chuck compatibility. At 8 mm in diameter and 4.61 inches overall length, it fits standard jobber length applications. Metalworkers, maintenance technicians, and fabricators use this bit for precision drilling in production and field environments.

This drill bit is suited for metal fabrication shops, maintenance and repair operations, and industrial production environments where consistent performance in hard metals is required. The 135-degree split point geometry minimizes thrust force and improves hole entry accuracy. The regular spiral flute with a 5xD flute-to-diameter ratio handles chip clearing efficiently in blind and through holes. It is appropriate for use in drill presses, CNC machining centers, and hand-held power drills with compatible chuck sizes.

Key Features

• M35 cobalt steel construction handles elevated drilling temperatures in hard alloys
• 135-degree split point reduces walking and lowers required thrust force
• Oxide and gold coating extends surface hardness and resists corrosion
• Two-flute right-hand spiral promotes consistent chip evacuation
• Straight cylindrical shank fits standard drill chucks without adapters
• 5xD flute-to-diameter ratio balances flute length with core strength

Compatibility

Designed as an OEM-style jobber length drill bit for use in standard drill chucks accepting 8 mm straight cylindrical shanks, including drill presses, CNC machining centers, and power hand drills.

Installation Notes

Installation of this drill bit is performed by qualified machinists or maintenance technicians familiar with rotating cutting tools. Ensure the drill chuck is fully secured and the workpiece is firmly clamped before operation. Apply cutting fluid appropriate for the workpiece material to reduce heat and extend bit life. Inspect the cutting edges and point geometry for wear before each use and replace the bit if chipping or dulling is observed.