Osg 1810900 Hand Sti Tap 8-32 Unc H3 Bottoming

Product Description

The OSG 1810900 is a hand STI tap designed for cutting Screw Thread Insert (STI) threads in a variety of metals. It produces the oversized internal threads required to accept helical coil thread inserts, restoring or upgrading thread strength in parent material. The tap is ground to an H3 thread limit and carries a 3-flute, bottoming-chamfer geometry, making it well suited for threading to the bottom of blind holes. Built from high speed steel with a bright finish, the 1810900 measures 2.125 inches overall length with a 0.75-inch thread length and a shank diameter of 0.168 inches. It is installed by hand with a standard tap wrench.

This tap is used wherever an 8-32 UNC Screw Thread Insert must be installed - common applications include repairing stripped threads in aluminum castings, carbon steel fabrications, cast iron housings, and hardened steel components. The bottoming chamfer allows threading into shallow or closed-end holes where a taper or plug chamfer cannot reach full thread depth. Typical users include machinists, maintenance technicians, and assembly professionals working on light mechanical assemblies, engine components, and equipment housings.

Key Features

• 8-32 UNC thread form ground to H3 thread limit for precise STI insert fitment
• Bottoming chamfer enables full threading to the base of blind holes
• 3-flute design provides chip clearance in a range of workpiece materials
• High speed steel construction handles aluminum, carbon steel, cast iron, and hardened steel
• Bright finish with no coating - ready for use with standard cutting fluids
• 0.75-inch thread length and 2.125-inch overall length suit compact workpieces

Compatibility

Designed for cutting 8-32 UNC STI threads compatible with standard helical coil thread inserts in aluminum, carbon steel, cast iron, and hardened steel parent materials per OSG Series 126.

Installation Notes

A qualified machinist or maintenance technician should install this tap using a properly sized tap wrench - never a power driver without a torque-limiting attachment. The parent hole must be drilled to the correct STI tap drill diameter before tapping. Apply a suitable cutting fluid for the workpiece material to extend tap life and improve thread finish. Inspect the tap for chipping or wear before each use; a damaged tap can seize in the workpiece and ruin the hole.