Cleveland C91710 Counterbore 5/16 in 6.000" L .438" dia. Bright

Cleveland C91710 Counterbore

The Cleveland C91710 is a high-speed steel counterbore with a built-in pilot designed for fractional inch applications. It suits machinists and maintenance technicians who need to create flat-bottomed holes for socket head cap screws. The bright finish provides corrosion resistance during storage and use. This tool is not for buyers who require carbide construction for abrasive materials or interchangeable pilot systems for varying hole diameters.

Sustained Load Behaviour

High-speed steel construction maintains cutting geometry during extended drilling cycles in mild steel and aluminium alloys. The integrated pilot ensures concentric alignment throughout the cut, reducing wander when operating at recommended speeds. Heat buildup is managed through standard coolant application rather than specialised coatings. The tool is not suited for continuous high-volume production runs where carbide tooling would reduce changeover frequency.

Installation and Common Issues

The counterbore fits directly into standard drill chucks or collets using its straight shank, requiring no adapter hardware. Setup time is minimal because the pilot is permanently fixed to the cutting body. Common issues include premature wear if run without adequate lubrication or chip evacuation in deeper cavities. Vibration can occur if the workpiece is not rigidly clamped, leading to chatter marks on the counterbore face.