Cleveland C91710 Solid Pilot Counterbore 15/32 in Hss

Product Description

The CLEVELAND C91710 is a solid pilot counterbore designed for precise, clean seat cutting in metal fabrication and mechanical assembly applications. Built from high-speed steel (HSS) with a bright, uncoated finish, this tool delivers consistent performance across alloy tool steel, carbon steel, and cast iron. The 15/32-inch counterbore diameter pairs with an 11/32-inch standard pilot to maintain accurate hole alignment during the cutting cycle. With 3 flutes and a forward cutting direction, the C91710 provides smooth chip evacuation and controlled material removal. The 7/16-inch straight cylindrical shank seats securely in standard drill press or milling machine toolholders.

This counterbore is sized specifically for 5/16-inch socket-head cap screws, making it the correct tool wherever that fastener requires a recessed seat. Typical applications include machine shop work, tooling fixture assembly, and field mechanical repair on steel structures or equipment. It suits machinists, maintenance technicians, and precision metalworkers who need a reliable, straight-shank counterbore for repeat production or one-off job work. The 6-inch overall length (OAL) provides adequate reach for standard workpiece thicknesses without sacrificing rigidity.

Key Features

• 15/32-inch counterbore diameter sized for 5/16-inch socket-head cap screw seating
• High-speed steel construction for use in alloy tool steel, carbon steel, and cast iron
• 3-flute geometry promotes smooth chip evacuation and reduced chatter
• Standard 11/32-inch pilot maintains concentricity with the existing drilled hole
• 7/16-inch straight cylindrical shank fits standard drill press and milling machine holders
• Bright, uncoated finish with forward cutting direction for general-purpose use

Compatibility

Designed for use with 5/16-inch socket-head cap screws. Compatible with alloy tool steel, carbon steel, and cast iron workpieces. Fits standard toolholders accepting a 7/16-inch straight cylindrical shank.

Installation Notes

This tool is installed and operated by machinists or maintenance technicians using a drill press, milling machine, or similar machine tool. Secure the shank fully in the chuck or collet and confirm the pilot seats properly in the pilot hole before beginning the cut. Set spindle speed appropriate to the workpiece material and tool diameter per standard HSS cutting speed charts. Do not use this tool in hand-held drill applications, as runout and instability will damage the pilot and compromise seat accuracy.