Hertel 66691387 Screw Machine Drill Bit 21/64 Cobalt

Product Description

The HERTEL 66691387 is a screw machine length drill bit designed for high-production drilling in metal fabrication, maintenance, and industrial trade applications. Built from cobalt steel with a titanium nitride (TiN) coating, it handles hard and abrasive materials where standard high-speed steel bits wear quickly. The 135-degree split point reduces walking at startup and lowers the thrust needed to penetrate the workpiece. At 2-15/16 inches overall length with a 1-11/16-inch flute length, this bit is sized for use in tight clearance setups such as drill presses, CNC machines, and hand drilling in confined spaces. It weighs 0.1 pounds and ships as a single unit.

This bit is suited for heavy-duty metalworking applications including drilling stainless steel, cast iron, titanium, and other difficult-to-machine alloys. The screw machine length body is shorter than a jobber-length bit, providing greater rigidity and reduced deflection during aggressive cuts. It is a practical choice for machinists, maintenance technicians, pipefitters, and metal fabricators who require consistent hole quality in production environments. The straight-cylindrical shank fits standard drill chucks without adapters.

Key Features

• Cobalt steel construction rated for heavy-duty drilling in hard and abrasive metals
• TiN coating extends cutting edge life and reduces friction during drilling
• 135-degree split point reduces bit walking and lowers required feed pressure
• Web-thinned, parallel web configuration for efficient chip evacuation
• Screw machine length body provides added rigidity versus jobber-length bits
• Right-hand spiral flute with straight-cylindrical shank fits standard drill chucks

Compatibility

Designed as an OEM-style replacement or direct-fit drill bit for standard drill chucks and collet systems accepting a 0.3281-inch straight-cylindrical shank across drill presses, CNC drilling centers, and hand-held power drills.

Installation Notes

This bit is installed by machinists and metal fabrication tradespeople using standard drill press or hand drill equipment. Secure the shank fully in the chuck and verify zero runout before beginning a cut. Always wear appropriate eye and hand protection when drilling metal. Use cutting fluid or coolant when drilling hard alloys to preserve coating life and edge integrity; note that this bit does not support coolant-through delivery.