Value Collection 186-4 Counterbore Pilot Hss 6 Inch

Product Description

The VALUE COLLECTION 186-4 is a counterbore pilot designed for use with countersink and counterbore tooling in metalworking and fabrication applications. It features a 3/16-inch head diameter and a 1/4-inch shank diameter, with an overall length of 6 inches. Constructed from high speed steel with a bright polished finish, it provides reliable guidance during counterboring operations, keeping the cutting tool centered over a pre-drilled hole. This type of pilot is typically installed and used by machinists, tool and die workers, and maintenance mechanics working with drill press or milling setups.

Counterbore pilots like the 186-4 are used in holemaking operations where a fastener recess must be accurately aligned with an existing pilot hole. The part fits into the pilot hole and guides the counterbore cutter concentrically, reducing runout and improving hole quality. It is suited for use in general metalworking, sheet metal fabrication, and light industrial maintenance environments where consistent hole geometry is required.

Key Features

• 3/16-inch head diameter for precise pilot hole engagement
• 1/4-inch shank diameter for standard toolholder compatibility
• 6-inch overall length for extended reach applications
• High speed steel construction for durability in metalworking operations
• Bright polished finish reduces friction and aids chip clearance
• Non-aircraft style configuration for general industrial use

Compatibility

Designed as a standard counterbore pilot accessory for use with compatible countersink and counterbore tooling requiring a 1/4-inch shank and 3/16-inch head diameter pilot.

Installation Notes

Counterbore pilots are installed by machinists and fabricators and should be seated securely in the tool body before operation. Ensure the machine spindle is fully powered down and locked out before changing or seating pilots. Verify the pilot diameter matches the pre-drilled pilot hole to maintain concentricity and avoid tool deflection during the cut.