Osg 1810500 Hand Sti Tap 6-32 Unc H3 Bottoming

Product Description

The OSG 1810500 is a hand STI tap designed to cut Screw Thread Insert (STI) threads in tapped holes, producing an oversized internal thread that accepts helical coil inserts for thread repair or reinforcement. Built from high speed steel with a bright finish, this tap covers 6-32 UNC thread geometry at an H3 thread limit, which controls pitch diameter tolerance for consistent fit with standard STI inserts. The bottoming chamfer allows threading close to the bottom of blind holes. Overall length is 2 inches, with a thread length of 11/16 inches and a shank diameter of 0.141 inches. Machinists and maintenance technicians use this tool in manual tapping operations on the bench or in the field.

This tap is suited for creating STI threads in a range of base materials including aluminum, carbon steel, cast iron, and hardened steel. It is most commonly applied in thread repair work where a damaged 6-32 UNC internal thread needs to be restored using a helicoil-style insert. The 3-flute geometry provides adequate chip clearance for through-hole and shallow blind-hole applications in these materials. The bottoming chamfer makes it the final step in a two-tap STI sequence when full thread depth near the bottom of a blind hole is required.

Key Features

• 6-32 UNC STI thread form for use with standard helical coil thread inserts
• Bottoming chamfer for threading to near full depth in blind holes
• H3 thread limit for controlled pitch diameter tolerance
• High speed steel construction handles aluminum, carbon steel, cast iron, and hardened steel
• 3-flute design provides chip clearance during hand tapping
• Bright finish, no coating - suitable for use with cutting oils and standard tapping fluids

Compatibility

Designed for use in STI thread repair applications requiring a 6-32 UNC oversized internal thread to accept standard helical coil insert systems. Compatible with aluminum, carbon steel, cast iron, and hardened steel workpieces per OSG Series 126 specification.

Installation Notes

This tool is installed and operated by machinists or maintenance technicians using a standard tap wrench or T-handle. Before tapping, ensure the workpiece is securely fixtured and the correct STI drill size has been used for the 6-32 UNC insert diameter. Apply an appropriate cutting fluid for the base material to extend tool life and improve thread quality. As a bottoming tap, use it as the final pass after a plug or taper STI tap has started the thread in the blind hole.