Osg 31401308 Spiral Point Sti Tap 3/8-16 Unc Plug

Product Description

The OSG 31401308 is a spiral point STI tap designed for cutting 3/8-16 UNC threads in through-hole applications. Built from powdered metal with a V finish, this plug chamfer tap drives chips forward ahead of the cutting zone, making it well suited for production tapping in materials where chip evacuation is critical. It carries a 3-3/8 inch overall length, a thread length of 1-21/32 inches, and is ground to H4 thread limit with a 2B class of fit. Licensed HVAC, plumbing, and mechanical tradespeople rely on STI taps to restore damaged threads or create new insert-ready holes in metal components and fixtures.

This tap is appropriate for through-hole tapping operations in ferrous and non-ferrous metals where a Heli-Coil or similar threaded insert will be installed after tapping. The spiral point design is best suited for through holes rather than blind holes, as the flute geometry pushes chips forward. It is used in maintenance, repair, and fabrication shops as well as on job sites requiring thread repair in structural or mechanical components.

Key Features

• Spiral point geometry evacuates chips forward, optimizing performance in through-hole applications
• Powdered metal construction provides wear resistance in production tapping environments
• V finish supports use across a range of common workpiece materials
• Plug chamfer (3-5 thread lead) provides a balance of starting ease and thread engagement
• H4 thread limit and 2B class of fit ensure accurate sizing for STI insert applications
• 3 flute configuration in OSG Series 314

Compatibility

Designed as an STI (Screw Thread Insert) tap producing 3/8-16 UNC threads sized to accept standard Heli-Coil style threaded inserts in through-hole configurations.

Installation Notes

This tap should be installed by a qualified machinist or maintenance technician using a calibrated tap handle or tapping machine set to appropriate feed and speed for the workpiece material. Secure the workpiece fully before tapping and apply cutting fluid appropriate to the material being tapped. Never force a tap — back off periodically to break chips even with a spiral point design. Follow shop safety practices and applicable workplace standards for rotating tooling.