Hertel 04139309 Cobalt Jobber Drill Bit Letter C

Product Description

The HERTEL 04139309 is a cobalt jobber-length drill bit sized to Letter C (0.2420 inches) for demanding holemaking applications in metal and hard materials. Built from heavy-duty cobalt steel with an oxide and TiN coating, it delivers extended tool life in ferrous and abrasive workpiece materials. The 135-degree split point reduces walking on entry and lowers thrust force, making it well suited for work on curved or irregular surfaces. The right-hand spiral flute with a regular helix evacuates chips efficiently. Overall length is 4 inches with a 2.75-inch flute length. Used by machinists, millwrights, and maintenance technicians working with drill presses, lathes, and hand-held power tools.

This drill bit is designed for general holemaking in production and maintenance environments. The straight-cylindrical shank seats securely in standard three-jaw chucks and keyless chucks without adapter sleeves. The web-thinned, tapered-web construction keeps cutting forces manageable when drilling steel, stainless, cast iron, and similarly hard materials. It is sold individually and is a practical stock item for tool cribs, job boxes, and machine shop consumable inventories.

Key Features

• Letter C sizing at 0.2420 inches decimal equivalent for precise hole sizing
• Cobalt construction with oxide and TiN coating for heat and wear resistance in hard metals
• 135-degree split point reduces thrust and minimizes bit walking on entry
• Right-hand regular spiral flute with web thinning for efficient chip evacuation
• Straight-cylindrical shank fits standard drill chucks without adapters
• Heavy-duty grade rated for continuous production and maintenance drilling

Compatibility

Designed as an OEM-style replacement jobber drill bit compatible with any drill press, CNC machine, lathe tailstock, or hand-held power drill accepting a straight-cylindrical shank of 0.2420 inches diameter.

Installation Notes

Installation is performed by machinists and maintenance technicians. Secure the shank fully in the chuck and verify runout before drilling. Always power down and lock out the machine before changing bits. Use cutting fluid or coolant appropriate to the workpiece material to protect the coating and extend tool life; coolant-through is not supported by this bit.