Guhring 9039900095250 Spiral Point Sti Tap 3/8-16 Unc

Product Description

The GUHRING 9039900095250 is a spiral point STI tap designed for through-hole threading operations in steel and stainless steel applications. Built from cobalt high-speed steel and finished with a titanium nitride (TiN) coating, this tap delivers improved wear resistance and longer tool life compared to standard HSS taps. It carries a 3/8-16 UNC thread size with a 3B class of fit and features a plug chamfer for smooth thread entry. With an overall length of 3.381 inches and a thread length of 0.512 inches, it fits standard tap holders used by machinists and maintenance technicians in production and field environments.

This tap is suited for threading inserts into damaged or oversized holes, which is the core application of STI (Screw Thread Insert) tooling. The spiral point geometry pushes chips ahead of the cutting edge, making it effective in through-hole setups where chip evacuation is critical. It is commonly used in automotive, industrial maintenance, and MRO applications where stainless steel and steel components require thread repair or new thread installation. The 3-flute design balances cutting efficiency with rigidity in these materials.

Key Features

• Cobalt high-speed steel construction for improved heat and wear resistance in hard materials
• Titanium nitride (TiN) coating extends tool life and reduces friction during cutting
• Spiral point geometry pushes chips forward, optimized for through-hole threading
• Plug chamfer provides gradual thread engagement and easy starting
• 3B class of fit for standard tolerance thread insert applications
• Series 3990 STI configuration for use with helical thread inserts

Compatibility

Designed for through-hole threading in steel and stainless steel workpieces using helical thread inserts at 3/8-16 UNC with a 3B class of fit. Compatible with standard tap holders accepting a 0.367-inch shank diameter.

Installation Notes

This tap should be installed and operated by a qualified machinist or maintenance technician familiar with thread repair tooling and STI procedures. Always secure the workpiece and use appropriate cutting fluid for cobalt taps working in stainless steel or steel to prevent galling and heat buildup. Confirm the correct pilot hole diameter for the specific thread insert being used before tapping. Do not exceed the recommended spindle speed for cobalt taps in the material being threaded.