Hertel H-81186040500 Combo Drill Countersink Size 4 Cobalt

Product Description

The HERTEL H-81186040500 is a combination drill and countersink tool designed for simultaneous drilling and countersinking operations in a single pass. Built from cobalt high-speed steel, it delivers superior heat and wear resistance compared to standard HSS tooling, making it well-suited for harder materials and higher-volume applications. The tool features a 5/16 inch body diameter, a 1/8 inch drill point diameter, a 118-degree drill point angle, and a 60-degree included angle for the countersink portion. Overall length is 5 inches. The bright polished finish reduces friction during cutting. Licensed machinists and toolroom technicians are the primary users.

This combo drill countersink is used in metal fabrication, aerospace-adjacent shop work, and general machining operations where a clean countersunk hole is required without a tool change. Trade size 4 designates the standard sizing classification for this style of center drill and countersink combination. The 5-inch overall length classifies this as a long-length tool, providing additional reach in setups where standard-length tools cannot access the workpiece. The double-end configuration allows the tool to be reversed and used from the opposite end when one end is worn, extending useful service life.

Key Features

• Cobalt construction for increased heat resistance and extended tool life in harder materials
• Double-end design allows reversal to the second cutting end when the first wears
• 118-degree drill point angle suitable for general-purpose metal drilling
• 60-degree included angle countersink matches standard flat-head fastener specifications
• Long-length at 5 inches overall for extended reach in deep or confined setups
• Bright polished finish reduces chip buildup and cutting friction

Compatibility

Designed as an OEM-style replacement or direct substitute for trade size 4 combo drill countersinks used in standard CNC and manual machining applications requiring a 5/16 inch body diameter and 1/8 inch drill point.

Installation Notes

This tool is installed in a standard drill chuck or collet-style tool holder on a drill press, lathe, or milling machine. Ensure the spindle is fully stopped and the machine is powered down before changing tooling. Use appropriate cutting fluid for the material being machined to maximize tool life. Follow shop safety protocols and applicable OSHA machine guarding standards when operating rotary cutting tools.