Hertel 66691577 Drill Bit Letter H Cobalt Tin 135 Point

Product Description

The HERTEL 66691577 is a screw machine length drill bit designed for high-production metal drilling in tight-clearance setups where a shorter overall length improves rigidity and reduces deflection. Built from heavy-duty cobalt steel with a titanium nitride (TiN) coating, this bit handles hard and abrasive materials including stainless steel, cast iron, and high-strength alloys. The 135-degree split point starts on contact without a center punch, and the web-thinned, parallel-web construction reduces thrust requirements. At 2-11/16 inches overall length with a 1-1/2 inch flute length, it fits standard drill chucks and machine spindles running a 0.2660-inch straight-cylindrical shank.

This bit is sized at Letter H, equivalent to 17/64 inch (0.2660 inches decimal), placing it in the 0.2500 to 0.3000 inch drill size range. Screw machine length geometry makes it well suited for drill presses, CNC machining centers, turret lathes, and hand-held power drills where stub-length tools are preferred. Machinists, toolroom operators, and maintenance mechanics typically reach for this style when drilling through hardened or work-hardening materials in production or repair environments. Right-hand spiral flutes clear chips efficiently during through-hole and blind-hole operations.

Key Features

• Cobalt steel construction with TiN coating for extended tool life in hard materials
• 135-degree split point starts on contact and reduces walking without a center punch
• Web-thinned parallel web lowers drilling thrust and feed force
• Screw machine (stub) length at 2-11/16 inches overall for improved rigidity
• Right-hand cut with regular spiral flutes for standard chip evacuation
• Heavy-duty grade rated for demanding production and maintenance applications

Compatibility

Designed as an OEM-style replacement or standard stock drill bit fitting any 3-jaw chuck or collet system that accepts a 0.2660-inch straight-cylindrical shank.

Installation Notes

Installation and use of this drill bit should be performed by a qualified machinist or maintenance professional familiar with cutting tool selection and machine operation. Secure the straight-cylindrical shank fully in a properly sized chuck or collet and verify runout before drilling. Always follow machine manufacturer guidelines for spindle speed, feed rate, and coolant application when drilling cobalt-coated tooling. Wear appropriate PPE including eye protection whenever drilling operations are in progress.