Harvey Tool 987116 Thread Mill 4-40 Internal 3 Flute Solid Carbide

Product Description

The HARVEY TOOL 987116 is a solid carbide helical flute thread mill designed for cutting internal 4-40 threads in a single helical pass. With a 0.0890-inch cutting diameter and a 0.2750-inch length of cut, this tool is engineered for precise thread milling in small-bore applications. The 3-flute geometry promotes chip evacuation and stable cutting action at 40 teeth per inch. At 2.0000 inches overall length and a 1/8-inch (0.1250-inch) shank diameter, it fits standard tool holders used in CNC machining centers. The bright, uncoated carbide finish suits a range of ferrous and non-ferrous workpiece materials. Licensed machinists and CNC programmers working on tight-tolerance threaded features are the primary users of this tool.

This thread mill is suited for internal thread milling in small-diameter holes requiring 4-40 UNC threads. It is commonly used in aerospace, electronics, medical device manufacturing, and precision mechanical assemblies where tapping is impractical or thread quality demands are high. The minimum nominal diameter for this tool is 0.1120 inches, setting the lower bound for hole size compatibility. CNC machining centers with helical interpolation capability are required for proper use. This tool does not support coolant-through delivery.

Key Features

• Cuts internal 4-40 threads at 40 TPI using helical interpolation
• Solid carbide construction for rigidity and wear resistance in small-diameter thread milling
• 3-flute design promotes chip clearance and cutting stability
• 0.0890-inch cutting diameter with 0.2750-inch length of cut for controlled thread depth
• Bright/uncoated finish compatible with a broad range of workpiece materials
• 1/8-inch shank diameter fits standard CNC collet and tool holder systems

Compatibility

Designed for use in CNC machining centers capable of helical interpolation. Minimum nominal hole diameter of 0.1120 inches is required. No specific compatible machine models are identified in the available product data.

Installation Notes

This tool must be run in a CNC machining center programmed for helical interpolation — it is not used in manual or tapping operations. Secure the 1/8-inch shank in a precision collet or end mill holder and verify runout before cutting. Confirm workpiece is rigidly fixtured before engaging the thread mill, as deflection at this tool diameter will directly affect thread quality. Follow the tool manufacturer speed and feed recommendations for the specific workpiece material.