Hertel 01778067 Cobalt Stub Drill Bit No. 20 135 Split Point

Product Description

The HERTEL 01778067 is a cobalt stub-length drill bit built for drilling into high-tensile strength metals. It uses a No. 20 wire size designation, equal to 0.1610 inches in diameter, and features a 135-degree split point for fast, accurate starts without center-punching. The oxide coating provides added surface hardness and lubricity. At 0.5625 inches overall length with a 5/16-inch flute length, this stub drill is designed for short-reach applications where rigidity and reduced deflection matter. The 1/4-28 threaded shank mates to compatible quick-change or threaded shank toolholders. Right-hand cutting with a regular spiral flute pattern. Recommended for general-purpose use in high-tensile metals.

This drill bit is suited for metalworking applications involving high-tensile strength alloys, hardened steels, stainless, and similar difficult-to-machine materials where standard HSS bits wear prematurely. The stub length reduces deflection and chatter, making it a practical choice for tight-clearance drilling, aerospace sheet metal work, and precision hole location. The web-thinned, tapered web geometry reduces thrust force at the cut. Produced to NAS 965 Type D specification, it meets requirements for aerospace and industrial applications where dimensional control is critical.

Key Features

• No. 20 wire size (0.1610 inches) cobalt construction for high-tensile metal drilling
• 135-degree split point for self-centering starts and reduced thrust
• Web-thinned, tapered web reduces cutting force in tough materials
• Stub length (0.5625 inches OAL) for maximum rigidity and minimal deflection
• Oxide coating adds surface hardness and lubricity
• 1/4-28 threaded shank for quick-change toolholder compatibility
• Meets NAS 965 Type D specification

Compatibility

Designed for use with 1/4-28 threaded shank toolholders. Suitable for general-purpose stub drilling in high-tensile strength metals per NAS 965 Type D specification.

Installation Notes

Installation and use of this drill bit should be performed by qualified machinists or maintenance trades familiar with metalworking equipment. Always secure the workpiece and confirm the toolholder is rated for the 1/4-28 threaded shank before operation. Inspect the cutting edges for wear or damage before each use and replace when performance degrades. Follow applicable shop safety protocols and machine manufacturer guidelines for speed and feed rates.