Hertel K007124AS Spiral Point Sti Tap 7/16-14 Unc

Product Description

The HERTEL K007124AS is a spiral point STI tap designed for cutting internal threads in pre-drilled holes intended for Helicoil-style thread inserts. Manufactured from high-speed steel with a bright, uncoated finish, this plug-chamfer tap drives chips forward through the hole during threading, making it well-suited for through-hole applications. It cuts a 7/16-14 UNC thread form to STI (Screw Thread Insert) specification at an H4 thread limit, ensuring the proper oversized diameter needed to accept a standard Helicoil or equivalent thread insert. Overall length is 3-19/32 inches with a thread length of 1-21/32 inches.

This tap is used when repairing stripped or damaged threads in ferrous and non-ferrous metals, or when installing thread inserts in new assemblies requiring enhanced thread strength. The STI profile produces a slightly enlarged thread that accepts a wire-form coil insert, restoring or upgrading the parent material to standard fastener size. Common applications include automotive, aerospace, and general industrial maintenance where thread repair with inserts is the specified method. Machinists, maintenance mechanics, and tool-and-die professionals install this tap in manual tap wrenches or low-speed tapping equipment.

Key Features

• STI UNC thread form sized for Helicoil-compatible coil inserts
• Spiral point geometry pushes chips ahead of the tap in through-hole operations
• Plug chamfer provides easy thread starting with a moderate lead-in angle
• High-speed steel construction offers good toughness across a range of workpiece materials
• H4 thread limit ensures consistent oversized fit for standard insert installation
• Bright, uncoated finish suitable for use with standard cutting fluids

Compatibility

Designed for use with Helicoil-style thread inserts for 7/16-14 UNC fasteners; Helicoil reference number 7CSA. Intended as an STI UNC tap for through-hole thread insert preparation.

Installation Notes

This tap is installed by a machinist or maintenance professional using a calibrated tap wrench or a low-speed tapping machine — high spindle speeds can damage the cutting edges and produce out-of-tolerance threads. Ensure the workpiece is securely fixtured and the tap is started perpendicular to the bore surface. Apply an appropriate cutting fluid for the workpiece material throughout the tapping operation. Follow the thread insert manufacturer's installation instructions for proper hole preparation drill size before using this STI tap.