Cleveland
Cleveland C91710 Counterbore 5/16 in 6.000" L .438" dia. Bright
A high-speed steel counterbore with built-in pilot for 5/16 in holes, 6.000 in long and .438 in diameter
- High-speed steel construction resists wear during repeated use
- Built-in pilot ensures accurate hole alignment without extra setup
- 5/16 inch fractional size matches standard fastener requirements
- 000 inch overall length provides reach for deep counterbores
- Bright finish reduces friction and improves chip evacuation
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.
Highlights
- High-speed steel construction resists wear during repeated use
- Built-in pilot ensures accurate hole alignment without extra setup
- 5/16 inch fractional size matches standard fastener requirements
- 000 inch overall length provides reach for deep counterbores
- Bright finish reduces friction and improves chip evacuation
Specifications
| Brand | CLEVELAND |
|---|
Questions about this item
How much heat does the high-speed steel counterbore generate during continuous drilling?
High-speed steel dissipates heat efficiently, letting the 6.000" long tool run all day without excessive temperature buildup.
What shank size must my drill chuck accept for the 5/16" counterbore to fit?
The counterbore uses a standard fractional-inch shank that matches a 5/16" drill chuck or collet.
Will the built-in pilot engage cleanly in pre-drilled holes from older drill bits?
The .438" diameter pilot aligns with standard fractional-inch holes, so it centers reliably in legacy workpieces.
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