Hertel 04139317 Cobalt Jobber Drill Bit Letter D

Product Description

The HERTEL 04139317 is a cobalt jobber-length drill bit sized to letter D (0.2460 inches) with a 135-degree split point and oxide/gold coating. Cobalt construction provides elevated heat resistance compared to standard high-speed steel, making it well suited for drilling into harder ferrous metals, stainless steel, and high-strength alloys where bit life is a concern. The split-point geometry reduces walking at startup and lowers the thrust force required to feed the bit into the material. Right-hand spiral flutes with regular helix evacuate chips efficiently during through-hole and blind-hole operations. Overall length is 4 inches with a 2.75-inch flute length and a straight-cylindrical shank at 0.2460 inches diameter.

This bit is intended for holemaking in metalworking applications across manufacturing, maintenance, and fabrication environments. The heavy-duty grade and cobalt material make it appropriate for interrupted cuts, hardened plate, and production drilling where standard HSS bits wear prematurely. The straight-cylindrical shank seats directly in standard drill chucks and collet systems without adapter hardware. It is sold and packaged individually and is a standard jobber-series length compatible with hand-held drills, drill presses, and CNC machining centers operating at appropriate feeds and speeds for cobalt tooling.

Key Features

• Cobalt material for increased heat and wear resistance over standard HSS bits
• 135-degree split-point tip reduces walking and lowers required feed pressure
• Oxide finish provides additional surface hardness and lubricity
• Right-hand spiral flute with regular helix for efficient chip evacuation
• Web-thinned, tapered web configuration reduces cutting resistance
• Heavy-duty grade rated for drilling harder ferrous and alloy materials

Compatibility

Designed as a jobber-series replacement drill bit for use in standard drill chucks and collet toolholders accepting a 0.2460-inch straight-cylindrical shank.

Installation Notes

A licensed machinist or qualified metalworking technician should verify correct feeds and speeds for the workpiece material before use, as cobalt bits require different parameters than standard HSS tooling. Secure the workpiece firmly before drilling to prevent movement or rotation. Use appropriate cutting fluid or coolant when drilling through hardened or stainless alloys to extend bit life and maintain dimensional accuracy. Inspect the shank and cutting edges before each use and replace if chipping, excessive wear, or deformation is observed.