Value Collection GH8840621 Counterbore 31/32 in 4 Flute Hss

Product Description

The VALUE COLLECTION GH8840621 is a 4-flute interchangeable pilot counterbore designed for enlarging and finishing bolt-seat holes to precise depths and diameters. Built from high-speed steel (HSS) with a bright, uncoated polished finish, this tool delivers durable cutting performance across a wide range of materials. The counterbore measures 31/32 inches in diameter with a 1/4-inch straight shank and an overall length (OAL) of 3.125 inches. The interchangeable pilot design accommodates a 3/16-inch pilot shank, allowing the cutter to be reused across different pilot sizes. Right-hand cutting direction is standard. Machinists, aerospace fabricators, and maintenance technicians are the primary users.

This counterbore is suited for aircraft-style applications where precise, flat-bottomed recesses are required for fastener seating. The aircraft style designation indicates it meets the tighter tolerances and geometry standards common in aviation and precision metalworking environments. It is appropriate for use in drill press, milling machine, and CNC setups where a controlled feed rate and rigid workholding are maintained. It handles ferrous and non-ferrous metals as well as plastics commonly encountered in fabrication and repair work.

Key Features

• 31/32-inch counterbore diameter for accurate bolt-seat recessing
• 4-flute geometry provides smooth, stable cutting action
• High-speed steel construction for durability across common metals and plastics
• Bright, uncoated polished finish suitable for general-purpose machining
• Interchangeable pilot accepts 3/16-inch pilot shank diameter
• Aircraft style designation meets precision tolerance standards
• Right-hand cutting direction; compatible with standard spindle rotation

Compatibility

Designed for use with 3/16-inch interchangeable pilots in standard counterbore tooling systems. Fits machines with a 1/4-inch straight shank collet or chuck capacity.

Installation Notes

This tool is installed and operated by machinists or qualified maintenance personnel using a drill press, milling machine, or CNC spindle. Secure the 1/4-inch straight shank firmly in a collet or Jacobs-style chuck before operation. Ensure the pilot is properly seated and the workpiece is rigidly fixtured to prevent chatter and maintain hole geometry. Always power down the machine and bring the spindle to a full stop before changing pilots or removing the tool.