Osg 1712501 Spiral Point Sti Tap 4-40 Unc 2 Flute

Product Description

The OSG 1712501 is a spiral point STI tap designed for tapping threads in insert-sized holes to accept STI (Screw Thread Insert) helicoil-type inserts. Built from vanadium high-speed steel with an oxide finish, this plug-chamfer tap handles 4-40 UNC threading in ferrous and non-ferrous metals. It carries a 2-flute spiral point geometry, which pushes chips ahead of the cutting edge to help maintain clean threads in through-hole applications. The H2 thread limit designation ensures tight dimensional control over thread tolerance. Overall length is 1.875 inches with a thread length of 0.362 inches, making it suited to shallow tapping applications where compact tooling is required.

This tap is used in maintenance, repair, and manufacturing environments where worn or damaged 4-40 UNC threads need to be restored using threaded inserts. Typical applications include aerospace, automotive, and general metalworking contexts where original threads have been stripped and insert reinforcement is the preferred repair method. It is installed using a standard tap wrench or machine tapping setup and is appropriate for both manual and light CNC tapping operations where controlled feed and torque are maintained.

Key Features

• Spiral point geometry pushes chips forward, reducing clogging in through-hole tapping
• Vanadium high-speed steel construction provides wear resistance across ferrous and non-ferrous materials
• Oxide finish reduces friction and offers moderate corrosion resistance during cutting
• Plug chamfer (3-5 thread lead) eases entry and distributes cutting load across multiple teeth
• H2 thread limit provides controlled tolerance for consistent STI insert fitment
• Compact 1.875-inch overall length suits close-clearance and confined tapping situations

Compatibility

Designed as an STI replacement tap for 4-40 UNC applications requiring helicoil-type threaded insert preparation. Compatible with standard STI insert installation systems for 4-40 UNC thread repair and new-thread applications.

Installation Notes

This tap is installed by machinists and maintenance technicians using a tap wrench or tapping head with appropriate alignment to the drilled hole. Always use a proper STI tap drill size for the target insert before threading. Apply cutting fluid appropriate to the workpiece material to extend tap life and improve thread quality. Inspect the tap for wear or chipping before each use and replace if cutting edges are degraded.