Osg 1206500 Spiral Point Tap 4-40 Unc 2 Flute Hss

Product Description

The OSG 1206500 is a spiral point tap designed for cutting 4-40 UNC internal threads in a wide range of metallic materials. Built from high-speed steel with a bright finish, this bottoming tap features 2 flutes and an H2 thread limit, making it well suited for threading operations that require close tolerances in a 2B or 3B class of fit. With an overall length of 1.875 inches and a thread length of 9/16 inch (0.319 inches), it delivers consistent thread form in shallow and through-hole applications. The right-hand thread direction and spiral point geometry help push chips forward during cutting, supporting efficient material removal in production and maintenance settings. Licensed machinists and toolroom technicians are the primary users.

This tap is appropriate for threading holes in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, high-carbon steel, and hardened steel. The bottoming chamfer style allows threads to be cut close to the bottom of a blind hole, which is critical in tight-tolerance assemblies where full thread engagement depth is required. The 4-40 UNC size is commonly found in small instrument enclosures, electronic hardware, and precision mechanical assemblies in both commercial and light industrial environments.

Key Features

• Bottoming chamfer for threading close to the bottom of blind holes
• H2 thread limit with 2B and 3B class of fit for consistent tolerance control
• High-speed steel construction for durability across a broad range of workpiece materials
• Spiral point geometry pushes chips forward to clear the cutting zone
• Right-hand thread direction, no coolant-through requirement
• Bright finish with no coating for straightforward inspection and regrinding

Compatibility

Designed to cut 4-40 UNC threads in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, high-carbon steel, and hardened steel workpieces per the OSG 105B series specification.

Installation Notes

This tap is installed and operated by machinists or toolroom professionals using a standard tap wrench, tapping head, or CNC machine tool. Secure the workpiece before tapping and ensure the pilot hole diameter matches the recommended tap drill size for 4-40 UNC. Apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish. Inspect the tap for wear or chipping before each use, as a damaged cutting edge can cause oversized threads or tap breakage.