Hertel 66691585 Screw Machine Drill Bit Letter I Cobalt

Product Description

The HERTEL 66691585 is a screw machine length drill bit designed for high-production drilling in metal, alloy steel, and hard materials. Built from heavy-duty cobalt steel with a titanium nitride (TiN) coating, it delivers extended tool life and improved wear resistance compared to standard high-speed steel bits. The 135-degree split point reduces walking and decreases thrust during entry, making it well suited for work on tough or hardened stock. At 2-11/16 inches overall length with a 1-1/2-inch flute length, the shorter-than-jobber-length body provides added rigidity in close-quarters drilling applications. The straight-cylindrical shank measures 0.2720 inches in diameter and chucks securely in standard drill chucks or CNC toolholders.

Screw machine length drill bits are a standard choice on CNC machining centers, turret lathes, and drill presses in industrial and production environments where shorter reach and reduced deflection matter. The Letter I designation corresponds to a decimal diameter of 0.2720 inches, placing it in the 0.2500 to 0.3000 inch size range. This bit is appropriate for machinists, tool-and-die shops, and maintenance technicians drilling through ferrous and non-ferrous metals, stainless steel, and other high-strength materials where a jobber-length bit would flex or chatter.

Key Features

• Heavy-duty cobalt steel construction for heat and wear resistance in hard-metal drilling
• TiN coating reduces friction and extends cutting edge life
• 135-degree split point minimizes walking and lowers required thrust force
• Web-thinned parallel web design improves chip evacuation and cutting efficiency
• Screw machine length body provides rigidity and reduced deflection versus jobber-length bits
• Right-hand spiral flute with straight-cylindrical shank for universal chuck compatibility

Compatibility

Designed as a direct-fit replacement for screw machine length Letter I drill bits in standard 3-jaw drill chucks, collet chucks, and CNC toolholding systems accepting a 0.2720-inch straight-cylindrical shank.

Installation Notes

Installation and use of this bit should be performed by qualified machinists or trade professionals familiar with drill press, lathe, or CNC machine operation. Ensure the machine spindle is fully stopped and locked out before changing tooling. Verify shank seating and chuck tightening to the machine manufacturer specification before initiating a cut. Use appropriate cutting fluid or coolant for the workpiece material to preserve coating integrity and edge life.