Hertel 4139671 Cobalt Jobber Drill Letter E 135 Deg

Product Description

The HERTEL 4139671 is a cobalt jobber-length drill bit sized to Letter E (0.2500 inch decimal equivalent) with a 135-degree split point and a titanium aluminum nitride (TiAlN) coating. The split point geometry reduces walking on entry and lowers thrust force, making it well suited for drilling harder ferrous and alloy materials. The TiAlN coating adds heat and wear resistance, extending service life in demanding holemaking applications. At 4 inches overall length with a 2.75-inch flute length, this is a standard jobber proportion for use in drill presses, CNC machining centers, and handheld power drills. It is classified as a heavy-duty grade bit and is sold individually.

This drill bit is intended for holemaking in metals including alloy steels, stainless steels, cast iron, and other hard materials where standard high-speed steel bits wear prematurely. The right-hand spiral flute and web-thinned, tapered web configuration improve chip evacuation and reduce heat buildup at the cutting edge. Typical applications include fabrication shops, maintenance and repair operations, and production environments where consistent, accurate hole sizing is required. It does not support coolant-through delivery.

Key Features

• Letter E size with 0.2500 inch decimal equivalent for precise hole sizing
• 135-degree split point reduces drill walk and decreases required thrust force
• TiAlN coating provides heat and wear resistance in high-temperature cutting conditions
• Cobalt construction improves toughness and heat resistance over standard HSS
• Web-thinned, tapered web for improved chip flow and reduced cutting resistance
• Straight-cylindrical shank accepts standard drill chucks without adapters

Compatibility

Designed as a standard jobber-length drill bit with a straight-cylindrical shank, compatible with any drill chuck sized to accept a 0.2500-inch shank diameter.

Installation Notes

Drill bits of this type are installed and serviced by machinists, fabricators, and maintenance technicians. Secure the shank fully in the chuck and confirm runout before drilling. Use appropriate cutting fluid or coolant for the workpiece material when possible, even though this bit does not support through-coolant. Inspect the cutting edges before each use and replace the bit if chipping or excessive wear is observed.