Value Collection GH8781486 Counterbore 1-3/4in 5 Flute 4MT Hss

Product Description

The VALUE COLLECTION GH8781486 is a 1-3/4 inch diameter interchangeable pilot counterbore designed for precision enlarging of pre-drilled holes and seating of fastener heads in metalworking applications. Built from high speed steel with a bright, uncoated and polished finish, this counterbore features five flutes and mounts via a No. 4 Morse Taper shank for rigid, concentric tool holding in compatible machine spindles. With an overall length of 8-1/8 inches, it provides the reach needed for deeper setups. The interchangeable pilot design accepts a 7/16 inch pilot shank, allowing the same body to be used across multiple fastener sizes when paired with the appropriate pilot. Right-hand cutting direction suits standard machine operation.

This counterbore is suited for job shop, production, and maintenance machining environments where spot facing, counterboring for socket head cap screws, or similar hole-finishing operations are required. The 4MT shank fits drill press, milling machine, and lathe tailstock spindles equipped with a No. 4 Morse Taper socket. Applications span general metalworking, fabrication, and MRO work on steel, cast iron, and similar ferrous materials. Not designated as aircraft style.

Key Features

• 1-3/4 inch counterbore diameter for large fastener head seating and spot facing
• Five-flute geometry for smooth cutting action and improved surface finish in the counterbored seat
• No. 4 Morse Taper shank for secure, self-holding fit in compatible machine spindles
• Interchangeable pilot accepts 7/16 inch pilot shank diameter for flexible use across fastener sizes
• High speed steel construction for durability across a range of ferrous workpiece materials
• Bright, uncoated and polished finish — no coating to chip or flake during regrinding

Compatibility

Designed for use in drill press, milling machine, or lathe tailstock spindles with a No. 4 Morse Taper (4MT) socket. Accepts a 7/16 inch interchangeable pilot shank. Right-hand cutting only.

Installation Notes

Installation and operation should be performed by a qualified machinist familiar with rotating tool safety practices. Ensure the machine spindle is fully stopped and locked out before mounting or removing the tool from the Morse Taper socket. Use a proper drift and drift slot to release the taper — do not strike the tool body directly. Verify pilot fit and tool runout before beginning the cut to prevent tool breakage or an out-of-specification counterbore.