Keo 902-000-050 Solid Pilot Counterbore 8mm 3 Flute

Product Description

The KEO 902-000-050 is a solid pilot counterbore designed for cutting clean, flat-bottomed recesses that seat socket-head cap screws flush with or below a workpiece surface. Manufactured from cobalt steel with a bright, uncoated finish, this tool delivers hardness and heat resistance suited to production and job-shop environments. It features a 8 mm counterbore diameter, a 4.3 mm standard pilot diameter, and 3 flutes for efficient chip evacuation and smooth surface finish. Machinists and toolroom professionals working in metal fabrication, maintenance, and general machining operations rely on this type of counterbore for consistent, repeatable results.

This counterbore is sized specifically for 4 mm socket-head cap screws and is intended for use in ferrous and non-ferrous materials where precise counterbore depth and diameter tolerances are required. The 5 mm shank diameter fits standard drill chucks and collet holders, and the 71 mm overall length provides adequate clearance for most vertical mill and drill press setups. Typical applications include machine frame assembly, fixture building, and general metalworking where fastener heads must be recessed.

Key Features

• 8 mm counterbore diameter sized for 4 mm socket-head cap screws
• 4.3 mm standard pilot diameter for accurate centering in the pilot hole
• 3-flute geometry promotes efficient chip removal and smooth finish
• Cobalt steel construction provides superior hardness and heat resistance over standard HSS
• Bright, uncoated finish compatible with cutting fluids and coolants
• 5 mm shank fits standard chucks and collet systems

Compatibility

Designed for use with 4 mm socket-head cap screws. Fits drill chucks and collet holders accepting a 5 mm shank diameter. Suitable as an OEM-style replacement or direct substitution in standard counterboring operations for this fastener size and pilot specification.

Installation Notes

This tool is installed and operated by machinists using a drill press, milling machine, or similar machine tool. Power down and secure the workpiece before changing or installing the counterbore. Use appropriate cutting fluid or coolant for the workpiece material to maximize tool life. Follow machine tool manufacturer guidelines for speed and feed selection when running cobalt steel tooling.