Osg 30200808 Spiral Flute Sti Tap 10-24 Unc Hss

Product Description

The OSG 30200808 is a high-speed steel spiral flute STI tap designed for cutting Screw Thread Insert (STI) threads in a range of workpiece materials. Built to 10-24 UNC specifications with a 45-degree helix angle and three right-hand flutes, this tap produces the oversized internal thread that accepts helical wire inserts such as Heli-Coil type repairs and new installations. The semi-bottoming chamfer allows threading closer to the bottom of a blind hole while still providing enough lead to start cleanly. Overall length is 2.5 inches, shank diameter is 0.255 inches, and thread length is 1 inch. It carries a V coating finish and conforms to a 2B class of fit with an H3 thread limit.

This tap is suited for production and maintenance applications in metalworking shops, aerospace MRO facilities, automotive repair, and general machine shops where stripped or worn threads require insert reinforcement. It is appropriate for use in aluminum, mild steel, cast iron, and similar materials at thread sizes calling for 10-24 UNC STI geometry. The Series 302 designation places it within the OSG standard STI tap line. Both new-build and repair scenarios where helical insert threads are specified are typical install contexts for this tool.

Key Features

• 10-24 UNC STI thread form for use with helical wire thread inserts
• 45-degree helix angle promotes chip evacuation in blind and through holes
• Semi-bottoming chamfer allows threading closer to blind-hole floors
• High-speed steel construction provides durability across a broad range of workpiece materials
• V finish coating helps reduce friction and improve tool life
• H3 thread limit and 2B class of fit ensure dimensional consistency

Compatibility

Designed as an OSG Series 302 STI tap for 10-24 UNC helical wire insert thread applications. Fits standard tap holders accepting a 0.255-inch shank diameter.

Installation Notes

This tap is intended for use by machinists and tooling technicians operating drill presses, CNC machining centers, or hand-tap setups. Always ensure the workpiece is securely fixtured and the spindle is powered down before changing tooling. Use appropriate cutting fluid for the workpiece material to extend tap life and maintain thread quality. Follow the insert manufacturer drill-size chart to prepare the correct STI pilot hole before tapping.