Cleveland C91700 Solid Pilot Counterbore 0.328in 3 Flute Hss

Product Description

The CLEVELAND C91700 is a solid pilot counterbore designed for creating accurate, flat-bottomed recesses for socket-head cap screws. Manufactured from high-speed steel (HSS) with a bright, uncoated finish, it features a 0.328-inch counterbore diameter, a 0.204-inch standard pilot diameter, and three flutes for controlled chip evacuation. The straight-cylindrical shank measures 5/16 inch in diameter and the tool runs 3.5 inches overall length. Cutting direction is forward. This counterbore is suited for machine shop, maintenance, and fabrication environments where precise socket-head cap screw seat preparation is required.

The C91700 is rated for use in alloy tool steel, carbon steel, and cast iron. It is sized for No. 10 socket-head cap screws, making it a common selection for mechanical assembly and fixture work where a clean, concentric counterbore is critical to fastener seating and joint integrity. The solid pilot design promotes accurate alignment with pre-drilled through-holes during operation.

Key Features

• 0.328-inch counterbore diameter sized for No. 10 socket-head cap screws
• 0.204-inch standard pilot diameter for accurate hole alignment
• 3-flute geometry supports controlled chip clearance in ferrous materials
• High-speed steel construction for use in alloy tool steel, carbon steel, and cast iron
• Bright uncoated finish suitable for general-purpose machining applications
• Straight-cylindrical 5/16-inch shank for standard drill press and milling machine collet compatibility

Compatibility

Designed for use with No. 10 socket-head cap screws. Compatible with alloy tool steel, carbon steel, and cast iron workpieces. Fits straight-cylindrical collets or chucks accepting a 5/16-inch shank diameter.

Installation Notes

Counterbore operations should be performed by a machinist or qualified tradesperson using a drill press, milling machine, or similar rigid setup. Secure the workpiece firmly before operation and set spindle speed appropriate for the workpiece material and tool diameter. Ensure the pilot engages the pre-drilled hole cleanly before feeding the cutter. Use cutting fluid appropriate to the workpiece material to extend tool life and improve surface finish.