Osg 8003602 Spiral Flute Sti Tap 4-40 Unc Hss

Product Description

The OSG 8003602 is a spiral flute tap designed for cutting Screw Thread Insert (STI) threads in a 4-40 UNC thread size. It is manufactured from High Speed Steel and features a 50-degree helix angle, which helps evacuate chips efficiently in blind-hole applications. The bottoming chamfer allows threading close to the bottom of a hole. With an elektraLUBE coating applied to the tool surface, the tap offers reduced friction during cutting operations. This tap is used by machinists, tool and die makers, and maintenance technicians working with small-diameter threaded inserts in metal components.

This tap is suited for threading operations that require STI thread profiles, which are oversized threads designed to accept helical coil inserts such as wire thread inserts used to restore or reinforce tapped holes. The 4-40 UNC thread size targets fine-pitch applications in small assemblies, electronics enclosures, and precision mechanical components. The 2-flute spiral design makes it appropriate for through-hole and shallow blind-hole work in ferrous and non-ferrous materials. It is a single-piece tool sized for use in standard tap handles, CNC tapping chucks, or drill press setups.

Key Features

• 4-40 UNC thread form for small-diameter STI tapping applications
• 50-degree helix angle promotes upward chip evacuation in blind holes
• Bottoming chamfer allows threading to near the base of a blind hole
• High Speed Steel construction provides wear resistance across a range of workpiece materials
• elektraLUBE finish reduces cutting friction and heat buildup during tapping
• H2 thread limit for standard tolerance STI thread fitment

Compatibility

Designed for use in STI tapping operations requiring a 4-40 UNC thread profile with an H2 thread limit, compatible with standard wire thread insert systems that use this thread size. Fits standard tap holders and chucks sized for small-diameter taps.

Installation Notes

This tool should be installed and operated by qualified machinists or tooling technicians familiar with tapping procedures for STI thread forms. Ensure the workpiece is securely fixtured and the tap is properly aligned before beginning the cut to avoid tap breakage in small-diameter threads. Use a suitable cutting fluid or tapping compound unless the elektraLUBE coating is relied upon for lubrication in the specific application. Inspect the tap for wear or damage before each use, as small-diameter taps are susceptible to breakage under side load or misalignment.