Osg 8015700 Spiral Flute Sti Tap 3/8-16 Unc Hss Bottoming

Product Description

The OSG 8015700 is a spiral flute STI (Screw Thread Insert) tap designed for cutting internal threads that accept Heli-Coil or similar wire thread insert systems. Built from high-speed steel with a bright finish, this tap produces a 3/8-16 UNC thread form with a 50-degree helix angle that promotes efficient chip evacuation in a range of workpiece materials. The bottoming chamfer geometry allows threading close to the bottom of blind holes. With an overall length of 2-15/16 inches, a shank diameter of 0.367 inches, and a thread length of 1-1/4 inches, this tap suits precision machining and maintenance-repair applications where insert-threaded connections are required.

This tap is suited for use in aluminum, carbon steel, cast iron, and hardened steel. It is commonly used in production machining, toolroom work, and field repair scenarios where a stripped or damaged thread needs to be restored using a wire thread insert. The right-hand flute direction is standard for conventional right-hand tapping operations. The 50-degree helix angle makes it particularly effective in through-hole and moderate-depth blind-hole applications across these material types.

Key Features

• 3/8-16 UNC thread form sized for STI applications accepting wire thread inserts
• 50-degree helix angle promotes forward chip flow and reduces chip packing
• Bottoming chamfer enables threading close to the base of blind holes
• High-speed steel construction provides durability across multiple material types
• Bright finish with H4 thread limit for controlled fit and dimensional accuracy
• Right-hand flute direction for standard tapping machine and hand-tap use

Compatibility

Designed for use with STI thread insert systems requiring a 3/8-16 UNC tap preparation. Compatible with aluminum, carbon steel, cast iron, and hardened steel workpieces per OSG Series S108 specifications.

Installation Notes

Installation should be performed by a machinist or qualified maintenance technician familiar with tapping operations and thread insert systems. Always use cutting fluid appropriate for the workpiece material to extend tap life and improve thread quality. Secure the workpiece and ensure the tap is aligned perpendicular to the work surface before beginning. Do not force the tap if resistance increases suddenly, as this indicates chip buildup or incorrect alignment.