Osg 12601500 Hand Sti Tap 9/16-12 Unc H3 Plug Chamfer

Product Description

The OSG 12601500 is a hand STI tap designed for cutting Screw Thread Insert (STI) threads in standard UNC applications. Built from high-speed steel with a bright finish, this tap produces a 9/16-12 UNC thread profile to the H3 thread limit, making it suitable for precision thread repair and new thread installation. The 4-flute plug chamfer design provides smooth chip evacuation and consistent thread form across a wide range of workpiece materials. With a thread length of 1.813 inches and an overall length of 4.031 inches, this tap is sized for typical hand-tapping operations in both production and repair environments. Machinists, maintenance technicians, and toolroom professionals are the primary users.

This tap is used in applications where damaged or stripped threads must be restored using helical coil inserts such as Heli-Coil style inserts. The STI thread profile is intentionally oversized relative to the standard UNC thread to accommodate the insert wall thickness, resulting in a finished threaded hole that accepts a standard 9/16-12 UNC fastener. Class of fit 3B ensures close-tolerance thread production suitable for precision assemblies. Typical applications include aerospace, automotive, heavy equipment repair, and general metalworking where thread repair is required without replacing the parent component.

Key Features

• 9/16-12 UNC STI thread profile for helical insert thread repair applications
• H3 thread limit for controlled tolerance and consistent class 3B fit
• 4-flute plug chamfer for balanced cutting action and smooth entry into the workpiece
• High-speed steel construction provides hardness and wear resistance across common workpiece materials
• Bright finish with no coating, suitable for use with cutting fluids
• Thread length of 1.813 inches and overall length of 4.031 inches sized for standard hand-tapping depth requirements

Compatibility

Designed for use in STI thread repair applications requiring a 9/16-12 UNC thread profile with H3 limit. Accepts helical coil inserts sized for standard 9/16-12 UNC fasteners. Verify insert manufacturer specifications to confirm STI tap size requirement before use.

Installation Notes

This tap is intended for hand tapping and should be operated with a proper tap wrench; do not use in power-driven applications unless the tool is explicitly rated for machine use. Ensure the workpiece is securely clamped and the tap is started square to the hole to avoid thread misalignment or tap breakage. Apply an appropriate cutting fluid for the workpiece material throughout the tapping operation. Follow established shop safety practices and consult material-specific machining data for feed and lubrication recommendations.