Hertel 18609 Countersink 5/16 in 100 Degree 4 Flute Hss

Product Description

The HERTEL 18609 is a single-piece countersink designed for creating tapered seat recesses in metal and similar materials prior to fastener installation. It features a 5/16 inch head diameter, a 100-degree included angle, and four flutes ground from high speed steel (HSS). The straight cylindrical shank measures 1/4 inch in diameter, making it compatible with standard drill chucks and quick-change tool holders. The four-flute geometry provides a smoother cut and reduces chatter compared to single-flute designs, making it suitable for production work as well as maintenance and repair operations.

This countersink is used to chamfer drilled holes to the correct angle for flat-head machine screws and similar fasteners. It is appropriate for use on ferrous metals, aluminum, and plastics in manufacturing, fabrication, and mechanical maintenance applications. The 100-degree included angle is commonly specified in aerospace and general industrial fastener seating applications where standard 82-degree or 90-degree angles are not required. Machinists, toolmakers, and maintenance technicians install this tool using a standard drill press, milling machine, or hand drill.

Key Features

• 5/16 inch head diameter for moderate-size fastener seating applications
• 100-degree included angle suits specific aerospace-style and industrial fastener requirements
• 4-flute design reduces chatter and produces a cleaner finish compared to fewer-flute alternatives
• High speed steel construction provides durability on ferrous and non-ferrous materials
• 1/4 inch straight cylindrical shank fits standard drill chucks and quick-change holders

Compatibility

Designed as an OEM-style replacement or direct addition for use in standard 1/4 inch shank tool holders, drill chucks, and quick-change collet systems commonly found on drill presses, lathes, and milling machines.

Installation Notes

A licensed machinist or trained technician should secure this countersink in a properly sized 1/4 inch drill chuck or collet before use. Ensure the workpiece is firmly clamped before applying the tool to avoid movement or tool breakage. Use appropriate cutting fluid when countersinking ferrous metals to extend tool life and improve finish quality. Do not exceed the tool's rated speed for the material being cut.