Cleveland C91713 Solid Pilot Counterbore 37/64 in 3 Flutes Hss

Product Description

The CLEVELAND C91713 is a solid pilot counterbore designed for precision counterboring of socket-head cap screw seat recesses in metalworking applications. Built from high-speed steel (HSS) with a bright, uncoated finish, it features a 37/64-inch counterbore diameter, a 25/64-inch standard pilot diameter, and three flutes for efficient chip evacuation. The 1/2-inch straight-cylindrical shank provides secure chuck engagement, and the 6.5-inch overall length accommodates a range of workpiece setups. Machinists and tool-and-die technicians use this counterbore with manual or CNC drilling equipment to produce clean, flat-bottomed recesses that seat socket-head cap screws flush or below the workpiece surface.

The C91713 is suited for use on alloy tool steel, carbon steel, and cast iron workpieces. The 3/8-inch fastener size compatibility makes it a direct-fit tool for preparing recesses that accept standard 3/8-inch socket-head cap screws. It is appropriate for production machining, maintenance-repair-overhaul (MRO) shops, and fabrication environments where consistent counterbore geometry and screw-seat concentricity are required. The standard pilot design ensures the counterbore tracks the existing through-hole accurately without requiring a separate piloting step.

Key Features

• 37/64-inch counterbore diameter sized for 3/8-inch socket-head cap screw seats
• 25/64-inch standard pilot diameter for accurate hole tracking
• Three-flute geometry promotes chip clearance and smooth cutting action
• High-speed steel construction handles alloy steel, carbon steel, and cast iron
• Bright, uncoated finish maintains dimensional accuracy without coating buildup
• 1/2-inch straight-cylindrical shank fits standard drill chucks and tool holders

Compatibility

Compatible with 3/8-inch socket-head cap screws. Designed for use on alloy tool steel, carbon steel, and cast iron workpieces. Straight-cylindrical 1/2-inch shank fits standard drill press and milling machine tool holders.

Installation Notes

This tool is installed and operated by machinists using drill presses, milling machines, or CNC machining centers. Secure the shank firmly in the chuck or collet before operation and verify the pilot fits the existing through-hole without excessive play. Run at speeds and feeds appropriate for HSS tooling in the specific workpiece material, and apply cutting fluid when machining steel to extend tool life. Inspect the pilot and cutting edges for wear before each use.