Osg 1712901 Spiral Point Sti Plug Tap 8-32 Unc

Product Description

The OSG 1712901 is a spiral point STI plug tap designed for tapping screw-thread inserts in ferrous and non-ferrous materials. It cuts an 8-32 UNC thread profile using three flutes arranged in a spiral point geometry that pushes chips forward ahead of the tap, reducing chip packing in through-hole applications. The tap is ground from vanadium high-speed steel for elevated wear resistance and toughness compared to standard M2 HSS. An oxide finish provides a baseline level of lubricity and corrosion protection. Overall length is 2.382 inches with a thread length of 0.44 inches. Thread limit is H3, suited to standard tolerance STI insert threads. This is a Series 301 OSG tap sold as a single unit.

This tap is used in machine shop, maintenance, and field repair applications where helical coil or STI-type thread inserts are being installed. Typical use cases include restoring damaged threads in aluminum engine components, steel structural members, and cast housings where a standard tap would not produce the correct insert-ready thread form. It is installed by machinists, tool-and-die technicians, and field service mechanics using a tapping machine, CNC machining center, or hand tap wrench depending on the job setup. The plug chamfer style makes it suitable for through holes and blind holes with adequate depth clearance.

Key Features

• Spiral point geometry pushes chips forward, reducing chip packing in through-hole tapping operations
• Vanadium high-speed steel construction provides improved wear resistance over standard HSS
• Oxide finish adds baseline lubricity and surface protection
• H3 thread limit ground for accurate STI insert-thread tolerances
• Plug chamfer style works in both through-holes and blind holes with sufficient depth
• Compact shank diameter of 0.22 inches fits standard tap holders and collets for this size range

Compatibility

Designed as an OEM-style STI plug tap for use with helical coil thread insert systems requiring an 8-32 UNC insert-ready thread form. Confirm insert manufacturer specifications for required tap series and thread limit before use.

Installation Notes

This tap should be installed and operated by qualified machinists or mechanics familiar with thread insert tapping procedures. Always secure the workpiece and use appropriate cutting fluid or tapping compound for the material being tapped. Verify spindle speed and feed rate against the tap manufacturer recommendations for the material; running too fast without lubrication is the primary cause of tap breakage. For hand tapping, use a calibrated tap wrench and advance the tap with consistent pressure, backing off periodically to break chips.