Hertel 84023910 Cobalt Stub Drill Bit 1/8 in 135 Pt

Product Description

The HERTEL 84023910 is a cobalt stub-length drill bit designed for drilling into high-tensile strength metals. It features a 135-degree split point that self-centers on contact, reducing the need for a center punch and minimizing walking on hard surfaces. The oxide coating provides additional surface hardness and mild corrosion resistance. With a 1/4-28 threaded shank, this bit is intended for use with compatible quick-change or threaded adapters rather than a standard chuck. Overall length is 0.5625 inches, making it a compact stub-type bit suited for tight-clearance drilling applications. This bit is installed and used by machinists, maintenance technicians, and metalworking trades.

This bit is designed for use in high-tensile strength metals including alloy steels, stainless steel, and similar hard materials where standard high-speed steel bits wear prematurely. The stub length and 5/16-inch spiral flute length are suited for shallow-hole applications where rigidity matters more than depth of cut. The right-hand cutting direction and regular spiral flute type make it compatible with standard drill press or hand-drill setups that accept a 1/4-28 threaded shank adapter. Typical applications include aerospace, automotive, and general metalworking environments where tight tolerances and hole quality are priorities.

Key Features

• Cobalt construction handles high-tensile strength metals where HSS bits fail
• 135-degree split point self-centers and reduces drill walk without a center punch
• Oxide coating adds surface hardness and mild corrosion resistance
• Stub length (0.5625 inches OAL) provides added rigidity in tight clearance situations
• 1/4-28 threaded shank for use with compatible quick-change adapter systems
• Web-thinned, tapered web configuration reduces thrust and improves chip evacuation

Compatibility

Designed for use with drill adapters or holders accepting a 1/4-28 threaded shank. Conforms to NAS 965 Type D specification. Suited for general-purpose metalworking applications involving high-tensile strength metals.

Installation Notes

This bit requires a threaded shank adapter or holder with a 1/4-28 female thread — it is not intended for use in a standard Jacobs-style chuck. Secure the adapter firmly before operation and verify the bit is fully seated to prevent runout. Use appropriate cutting fluid when drilling hard alloys to extend bit life and maintain hole quality. Follow applicable shop safety standards for rotating machinery when operating drill presses or hand drills.