Osg 7018300 Spiral Point Sti Tap 3/8-24 Unf Hss

Product Description

The OSG 7018300 is a spiral point STI (Screw Thread Insert) tap designed for cutting 3/8-24 UNF internal threads in preparation for helical insert installation. Built from high-speed steel with a bright, uncoated finish, this plug-chamfer tap produces clean through-hole threads in a single pass. It features 3 flutes and a spiral point geometry that pushes chips forward ahead of the cutting edge, reducing chip packing and improving thread quality. With an overall length of 2-15/16 inches and a thread length of 1-1/4 inches, it suits standard drill press and hand-tap applications in metal fabrication, maintenance, and repair work.

This tap is used in applications where a standard thread requires reinforcement via a helical coil insert, such as STI (Screw Thread Insert) repairs or OEM manufacturing builds requiring insert-ready threads. The 3/8-24 UNF fine-thread profile is commonly found in automotive, aerospace, and precision mechanical assemblies. The plug chamfer - with a standard lead-in taper - makes it suitable for through-hole tapping. Machinists, maintenance technicians, and fabricators working in metal repair or production environments are the primary users of this tool.

Key Features

• Spiral point geometry pushes chips forward to reduce clogging in through-hole tapping
• 3/8-24 UNF thread profile for fine-thread STI applications
• High-speed steel construction provides durability across a range of ferrous and non-ferrous materials
• Plug chamfer provides standard lead-in taper for through-hole threading
• H3 thread limit for consistent fit with standard STI helical inserts
• Bright, uncoated finish suitable for use with cutting fluids in general-purpose tapping

Compatibility

Designed for use with 3/8-24 UNF STI helical coil insert systems in through-hole tapping applications. Verify insert manufacturer specifications to confirm pre-drill diameter and thread limit requirements before use.

Installation Notes

This tap is installed using a standard tap wrench or machine tap holder; ensure the workpiece is securely clamped and the drill axis is aligned before threading begins. Apply cutting fluid appropriate for the workpiece material to extend tap life and improve thread finish. Follow standard machining safety practices, including securing loose clothing and using eye protection. Inspect the tap for wear or chipping before each use to avoid thread damage or tap breakage.