Cleveland C91711 Solid Pilot Counterbore 1/2 in Hss

Product Description

The CLEVELAND C91711 is a solid pilot counterbore designed for precise counterboring operations in machine shop and fabrication environments. Built from high-speed steel with a bright uncoated finish, this tool features a 1/2 inch counterbore diameter, an 11/32 inch standard pilot diameter, and 3 flutes for forward cutting. The 7/16 inch straight cylindrical shank and 6 inch overall length make it compatible with standard milling and drill press setups. It is sized specifically for 5/16 inch socket-head cap screws, allowing machinists to create clean, accurately sized counterbores for fastener seating without secondary operations.

This counterbore is suited for use on alloy tool steel, carbon steel, and cast iron workpieces in manufacturing, maintenance, and toolroom applications. It is a single-piece solid pilot design, which provides improved rigidity and concentricity compared to interchangeable-pilot styles. Machinists, tool-and-die workers, and industrial maintenance technicians will find it appropriate for both production and repair work where consistent counterbore geometry is required for socket-head cap screw installations.

Key Features

• 1/2 inch counterbore diameter sized for 5/16 inch socket-head cap screws
• 11/32 inch standard solid pilot for improved concentricity and alignment
• 3-flute forward-cutting geometry for efficient chip evacuation
• High-speed steel construction handles alloy tool steel, carbon steel, and cast iron
• Bright uncoated finish suitable for use with cutting fluid
• 7/16 inch straight cylindrical shank fits standard drill press and milling machine chucks

Compatibility

Designed for use with 5/16 inch socket-head cap screws. Suitable for counterboring alloy tool steel, carbon steel, and cast iron workpieces. Fits machine setups that accept a 7/16 inch straight cylindrical shank.

Installation Notes

This tool is installed and operated by machinists and toolroom technicians using a drill press, milling machine, or similar spindle equipment. Secure the shank firmly in a compatible chuck or collet before operation and verify that the workpiece is clamped to prevent movement. Always apply an appropriate cutting fluid when working with steel or cast iron to extend tool life and maintain surface finish quality. Inspect the pilot for wear before use, as pilot damage will affect counterbore concentricity.