Value Collection 191-4J Reverse Counterbore Solid Carbide

Product Description

The VALUE COLLECTION 191-4J is a solid carbide reverse counterbore designed for spot facing operations on the blind side of a workpiece. With a 7/16-inch cutting diameter and a 1/8-inch pilot hole, this tool produces clean, flat bearing surfaces in locations that are inaccessible from the front. The 4-flute geometry promotes chip evacuation and surface finish quality. At 1/2 inch overall length, it is sized for compact access in tight setups. A 1/64-inch corner radius reduces edge stress at the counterbore shoulder. Machinists and toolroom technicians use this tool in metalworking, aerospace prep, and general machining applications.

This reverse counterbore is suited for holemaking and porting operations where a standard counterbore cannot reach. It is used in applications requiring a recessed seating surface on the back face of a part, such as bolt-hole spot facing in fabricated assemblies. The solid carbide construction supports use in harder workpiece materials and higher-speed setups. It is compatible with standard pilot model 185-2 and oversize pilot model 186-2, allowing the operator to match pilot fit to hole tolerance.

Key Features

• 7/16-inch counterbore diameter for reverse spot facing operations
• 1/8-inch pilot hole diameter for precise tool alignment
• 4-flute solid carbide construction for rigidity and wear resistance
• 1/2-inch overall length for compact, low-clearance setups
• 1/64-inch corner radius reduces stress concentration at the counterbore shoulder
• Compatible with standard pilot 185-2 and oversize pilot 186-2

Compatibility

Accepts standard pilot model number 185-2 and oversize pilot model number 186-2. Designed as a reverse counterbore for spot facing applications in metalworking and machining environments.

Installation Notes

This tool is installed and operated by machinists or toolroom technicians using compatible pilot-and-arbor setups. Secure the workpiece fully before engaging the cutter to prevent movement during reverse spot facing. Power down the machine and verify zero spindle rotation before changing pilots or inspecting the cutting edges. Inspect carbide flutes for chipping before each use, as solid carbide is brittle under impact or lateral loading.