Value Collection GH8840563 Pilot Counterbore 7/8 in 4 Flute Hss

Product Description

The VALUE COLLECTION GH8840563 is an interchangeable pilot counterbore designed for precision counterboring operations in metal fabrication and aircraft-style drilling applications. Built from high-speed steel with a bright, polished, uncoated finish, this tool features a 7/8-inch counterbore diameter and a 1/4-inch straight shank for secure chuck engagement. Four cutting flutes provide efficient material removal with a right-hand cutting direction. With an overall length of 3-1/8 inches and compatibility with a 3/16-inch pilot shank, this counterbore is suited for machinists, tool-and-die tradespeople, and maintenance technicians who require consistent, repeatable bore geometry in production or repair environments.

This counterbore is intended for use in machining centers, drill presses, and hand-operated setups where a flat-bottomed recess is needed to seat fastener heads flush or below a workpiece surface. The aircraft-style designation indicates suitability for close-tolerance applications common in aerospace component work, precision sheet metal assembly, and structural repair. The straight shank fits standard 1/4-inch collets and drill chucks, making it compatible with a wide range of machine tool setups found in shop and field environments.

Key Features

• 7/8-inch counterbore diameter for flat-bottomed recess machining
• High-speed steel construction provides hardness and wear resistance across a range of workpiece materials
• Bright, polished, uncoated finish for smooth chip evacuation and dimensional accuracy
• Four flutes with right-hand cutting direction for efficient material removal
• Interchangeable pilot design accepts a 3/16-inch pilot shank for guided, concentric boring
• Aircraft-style geometry suited to close-tolerance fastener seating applications

Compatibility

Designed as a replacement or additional-stock counterbore for setups requiring a 7/8-inch counterbore diameter with a 3/16-inch interchangeable pilot and a 1/4-inch straight shank. Confirm pilot shank diameter and counterbore diameter requirements against your fastener specification before installation.

Installation Notes

Installation of this counterbore is performed by qualified machinists or maintenance technicians. Secure the 1/4-inch straight shank firmly in a compatible collet or drill chuck before operation, and verify that the correct pilot diameter is seated properly before engaging the workpiece. Ensure the workpiece is clamped securely and the machine spindle is at the appropriate speed for the workpiece material and tool diameter. Always power down and de-energize or lock out the machine before changing tooling or inspecting the cutting edges.