Hertel 66691544 Drill Bit Letter D Cobalt Tin 135 Deg

Product Description

The HERTEL 66691544 is a screw machine length drill bit designed for high-production drilling in metal fabrication, machining, and general industrial applications. Built from heavy-duty cobalt steel with a titanium nitride (TiN) coating, it delivers extended tool life in hard and abrasive materials. The 135-degree split point reduces walking and cutting thrust at entry, and the web-thinned, parallel-web construction improves chip evacuation. At 2.5 inches overall length, this short-series bit fits standard drill presses, CNC machining centers, and hand-held power tools where rigidity and reduced deflection matter most.

This bit is sized at Letter D (0.2460 inches diameter) and is suited for drilling ferrous and non-ferrous metals including stainless steel, cast iron, and hardened alloys. The screw machine length format is a common choice in production environments where tooling clearance is limited and hole location accuracy is critical. Right-hand spiral flutes with a 1.375-inch flute length handle chip removal effectively in both through-hole and blind-hole operations. The straight cylindrical shank at 0.2460 inches fits standard drill chucks without adapters.

Key Features

• Letter D size - 0.2460 inches diameter, fits standard 3-jaw drill chucks directly
• Cobalt steel construction rated for heavy-duty cutting in hard and abrasive materials
• TiN coating extends tool life and reduces heat buildup during cutting
• 135-degree split point minimizes walk and reduces entry thrust
• Web-thinned parallel web improves chip flow and reduces cutting load
• Screw machine (stub) length provides maximum rigidity and reduced deflection

Compatibility

Designed as an OEM-style replacement or production consumable for use in drill presses, machining centers, and power tools accepting a 0.2460-inch straight cylindrical shank drill bit.

Installation Notes

Installation and use should be performed by machinists or qualified trade professionals familiar with drill press and CNC tooling safety procedures. Secure the shank fully in the chuck and verify runout before use. Always wear appropriate eye protection and secure the workpiece before drilling. Inspect the cutting edge for wear or chipping before each use, as a damaged point on a cobalt bit can fracture under load.