Harvey Tool 987116-C8 Thread Mill 4-40 Internal Solid Carbide

Product Description

The HARVEY TOOL 987116-C8 is a solid carbide helical flute thread mill designed for cutting internal 4-40 UNC threads in a single helical pass. With a 0.0890-inch cutting diameter, a 0.2750-inch length of cut, and a 1/8-inch (0.1250-inch) shank, this tool is built for tight-tolerance threading in small-diameter holes. The three-flute geometry promotes chip evacuation and stable cutting action. A Titanium Diboride (TiB2) coating reduces friction and improves wear resistance, extending tool life in abrasive or hardened workpiece materials. Machining professionals and tool-and-die shops use this mill in CNC machining centers where thread milling is preferred over tapping for precision or material-specific requirements.

This thread mill is suited for internal threading operations on small fastener holes requiring a 4-40 thread profile with 40 teeth per inch. The 2.000-inch overall length provides adequate reach for most standard workpiece setups. The minimum nominal hole diameter for this tool is 0.1120 inches, making it appropriate for close-clearance bores. It is used in production machining, prototype work, and repair applications where a dedicated tap would risk breakage or where thread quality demands are high. CNC machinists, mold makers, and precision machine shops are the primary users.

Key Features

• Solid carbide construction for rigidity and dimensional stability in demanding materials
• Titanium Diboride (TiB2) coating reduces friction and extends tool life
• Three-flute helical design promotes chip flow and smooth thread form
• Cuts 4-40 internal threads at 40 TPI in a single helical interpolation pass
• 0.1250-inch shank diameter fits standard ER collets and small-bore tool holders
• 2.000-inch overall length with 0.2750-inch length of cut for precise depth control

Compatibility

Designed for use in CNC machining centers capable of helical interpolation. Requires a minimum nominal bore diameter of 0.1120 inches. Compatible with standard 1/8-inch ER collet tool holders.

Installation Notes

Thread milling requires a CNC control with helical interpolation capability. Secure the tool in a precision collet chuck and verify runout before cutting. Always program the correct thread lead and helix direction for the desired thread hand. Do not use in manual or non-interpolating machines, as this tool is not designed for direct axial threading.