Hertel 04139382 Cobalt Jobber Drill Bit Letter K

Product Description

The HERTEL 04139382 is a cobalt jobber-length drill bit sized to letter K (0.2810 inches decimal equivalent), designed for heavy-duty holemaking in ferrous and abrasive materials. It features a 135-degree split point that reduces walking and requires no center punch on most surfaces. The oxide and TiN coating provides added surface hardness and lubricity. With an overall length of 4.25 inches and a flute length of 2.9375 inches, this bit suits standard jobber-length drilling applications. It cuts right-hand with a regular spiral flute and a web-thinned, tapered web for reduced thrust. Machinists, maintenance technicians, and metalworking trades are the primary installers.

This drill bit is appropriate for production and maintenance drilling operations where cobalt-grade tooling is specified for harder steels, stainless alloys, or high-temperature materials. It fits standard drill chucks and CNC spindles accepting a straight cylindrical shank of 0.2810 inches. The jobber-series length makes it suitable for general-purpose through-hole and blind-hole work in both shop and field environments. It is sold individually and is well suited for single-replacement use or as a stock replenishment unit.

Key Features

• Letter K size at 0.2810 inches decimal for precise hole sizing
• 135-degree split point reduces thrust and eliminates center-punch requirement on most materials
• Cobalt construction with oxide and TiN coating for extended tool life in hard or abrasive materials
• Web-thinned tapered web lowers cutting resistance and heat buildup
• Right-hand regular spiral flute for efficient chip evacuation
• Straight cylindrical shank fits standard three-jaw drill chucks and collet holders

Compatibility

Designed as a general-purpose jobber-length drill bit fitting any standard drill chuck or CNC spindle that accepts a 0.2810-inch straight cylindrical shank across the letter-size drill range of 0.2500 to 0.3000 inches.

Installation Notes

This bit is installed by machinists and metalworking technicians using standard drill presses, CNC machining centers, or portable drills. Secure the shank fully in the chuck before operation and verify runout is within acceptable limits for the application. Use appropriate cutting fluid or coolant when drilling harder alloys to preserve coating integrity and edge life. Inspect the cutting edges before each use and replace the bit if chipping or excessive wear is observed.