Osg 7017400 Spiral Point Sti Tap 3/8-16 Unc Hss

Product Description

The OSG 7017400 is a spiral point STI tap designed for cutting 3/8-16 UNC threads in steel insert applications. Built from high-speed steel (HSS) with a bright, uncoated finish, this plug-chamfer tap features 3 flutes and an H4 thread limit for consistent tolerance control. It measures 2-15/16 inches overall length with a 1-1/4 inch thread length and a shank diameter of 0.367 inches. The spiral point geometry pushes chips forward through the hole, making it well suited for through-hole tapping operations in production and maintenance environments. Machinists and maintenance technicians working with STI (Screw Thread Insert) applications rely on this tap when installing thread inserts such as Heli-Coil style repairs.

This tap is used in through-hole tapping for STI thread inserts requiring a 3/8-16 UNC thread form. It fits CNC machining centers, drill presses, and hand-tapping setups in both shop and field environments. The plug chamfer allows the tap to start easily in a pre-drilled hole and progress through the full thread depth with minimal effort. Typical applications include creating oversized threads to accept thread repair inserts in worn or damaged bores in metal components across manufacturing, repair, and maintenance settings.

Key Features

• Spiral point geometry pushes chips forward, ideal for through-hole tapping
• 3/8-16 UNC thread form with H4 thread limit for tight tolerance fitment
• 3 flutes for efficient chip evacuation and smooth cutting action
• High-speed steel construction for durability across a range of steel and ferrous workpieces
• Plug chamfer for easy starting and full-depth threading in through-hole applications
• Bright, uncoated finish suitable for use with standard cutting fluids

Compatibility

Designed for STI (Screw Thread Insert) tapping applications requiring a 3/8-16 UNC thread form in through-holes. Compatible with standard drill press, CNC, and hand-tap setups using appropriate tap holders for straight-shank taps.

Installation Notes

Installation should be performed by a qualified machinist or maintenance technician familiar with tapping operations. Always drill the correct STI tap drill size for the thread insert being used before threading with this tap. Use an appropriate cutting fluid for the workpiece material to extend tap life and improve thread quality. Secure the workpiece fully before tapping and ensure the tap enters the hole square to avoid cross-threading or tap breakage.