Heli-coil 3724-14 Thread Insert Tool 7/8-9 Unc

Product Description

The HELI-COIL 3724-14 is a hand installation tool designed for driving threaded wire inserts into tapped holes. It uses a Type III threaded mandrel to engage the insert tang and drive the coil flush or below the surface of the host material. Compatible with both free-running and locking insert styles, this tool is suited for 7/8-9 UNC thread sizes. At 4-7/8 inches in overall length and a 4-1/2 inch spinner diameter, it gives the installer enough mechanical advantage for controlled, repeatable insertion by hand without power tools.

This tool is used wherever HELI-COIL or equivalent wire thread inserts are installed in stripped, damaged, or understrength threaded bores. Typical applications include engine block repairs, heavy equipment component threads, structural fastener locations, and industrial maintenance work. It is used by machinists, maintenance mechanics, and field service technicians across aerospace, automotive, and general industrial trades. The 7/8-9 UNC designation makes it appropriate for coarse-thread applications in ferrous and non-ferrous base materials.

Key Features

• Type III threaded mandrel drives 7/8-9 UNC free-running and locking inserts
• 4-7/8 inch overall length provides hand-torque leverage for controlled installation
• 4-1/2 inch spinner diameter supports smooth, stable one-hand operation
• Compatible with both free-running and locking insert styles in the 7/8-9 size range
• UNC thread standard matches standard coarse-pitch inch-series inserts

Compatibility

Designed for use with HELI-COIL free-running and locking thread inserts in the 7/8-9 UNC size. Verify insert series and coil diameter before use to confirm correct mandrel fitment.

Installation Notes

Installation is performed by hand without power tools. The tapped hole must be prepared to the correct HELI-COIL tap size for 7/8-9 UNC before the insert is driven. Engage the mandrel onto the insert tang, align the insert with the hole, and turn the spinner clockwise until the insert seats at the specified depth. After seating, break off the drive tang with a punch if required by the application.