Value Collection GH8781320 Counterbore 1-1/2 in 5 Flute 4MT

Product Description

The VALUE COLLECTION GH8781320 is a 5-flute interchangeable pilot counterbore designed for enlarging and finishing bolt-seat holes to precise tolerances in metal fabrication and machining applications. The tool features a 1-1/2 inch cutting diameter and a 4MT (No. 4 Morse Taper) shank for rigid, self-centering mounting in compatible taper-socket spindles. Constructed from high-speed steel (HSS) with a bright, uncoated polished finish, it delivers reliable cutting performance on steel, cast iron, and similar ferrous materials. The interchangeable pilot design accommodates a 3/8 inch pilot shank diameter, allowing the counterbore to be paired with separate pilots sized to the clearance hole being machined. Right-hand cutting direction. Overall length is 7-7/8 inches.

This counterbore is suited for job shop, toolroom, and production machining environments where accurate bolt-hole spotfacing or counterboring is required. Typical applications include creating flat bearing surfaces for fastener heads and washers on structural assemblies and machined components. The Morse taper shank mounts directly in drill press and milling machine spindles equipped with a No. 4 Morse Taper socket. The interchangeable pilot system allows a single body to serve multiple hole sizes by swapping pilots, reducing tooling inventory requirements.

Key Features

• 1-1/2 inch counterbore diameter with 5-flute geometry for smooth chip evacuation and a clean seat finish
• No. 4 Morse Taper (4MT) shank provides rigid, self-centering clamping without a separate arbor
• Interchangeable pilot accepts 3/8 inch pilot shank diameter pilots for flexible hole-size coverage
• High-speed steel construction offers toughness and regrindability for extended tool life
• Bright, uncoated polished finish suitable for general-purpose ferrous and non-ferrous cutting
• Right-hand cutting direction; 7-7/8 inch overall length for reach in deeper setups

Compatibility

Designed for use in drill press or milling machine spindles with a No. 4 Morse Taper socket. Accepts interchangeable pilots with a 3/8 inch pilot shank diameter. Verify spindle taper designation and pilot shank size before installation.

Installation Notes

Installation should be performed by a qualified machinist. Ensure the machine spindle is fully de-energized and locked out before seating or removing the Morse taper shank. Clean both the taper shank and spindle socket thoroughly before insertion to ensure full contact and prevent fretting. Secure the interchangeable pilot to the correct torque per shop practice before beginning the cut, and never exceed the rated speed for the tool diameter and material being machined.