Heli-coil 18187-16 Hand Sti Tap 1-8 Unc H6 Plug Chamfer

Product Description

The HELI-COIL 18187-16 is a hand STI tap designed to cut threads for Screw Thread Insert installation in 1-8 UNC applications. Built from high speed steel with a bright finish, it produces a Class 2B thread fit to the H6 thread limit. The 4-flute, plug chamfer design provides a gradual lead-in and smooth cutting action suited to through-hole and moderately deep blind-hole work. With an overall length of 5.75 inches and a thread length of 2.5625 inches, this tap handles the full thread engagement depth required for most insert installations. Licensed HVAC, plumbing, and general mechanical trades use this tool when threading parent material to accept HELI-COIL wire inserts.

This tap is used in repair and fabrication applications where stripped or damaged threads in metal components need to be restored to specification using threaded wire inserts. It is appropriate for use in aluminum, cast iron, steel, and other machinable metals. The plug chamfer style makes it suitable for hand-tapping operations where a starting chamfer is needed before full thread engagement. Typical scenarios include field repair of tapped holes in HVAC equipment housings, compressor flanges, and plumbing manifold assemblies where insert installation restores original thread integrity.

Key Features

• 1-8 UNC thread size with H6 thread limit for precision STI thread production
• 4-flute geometry delivers consistent chip clearance and smooth cutting in hand-tapping operations
• Plug chamfer provides controlled lead-in, suitable for through holes and moderately deep blind holes
• High speed steel construction resists wear during repeated use in metallic materials
• Bright finish with 5.75-inch overall length accommodates deep-reach hand-tapping scenarios
• Class 2B fit standard ensures proper engagement with HELI-COIL inserts after installation

Compatibility

Designed for use with HELI-COIL screw thread insert systems in 1-8 UNC thread applications requiring an H6 thread limit and Class 2B fit.

Installation Notes

This tap is installed by hand using an appropriate tap wrench; power driving is not recommended for hand STI taps. Ensure the workpiece is secured and the hole is drilled to the correct STI tap drill diameter before tapping. Apply cutting fluid appropriate for the parent material to extend tool life and improve thread quality. Always back the tap out periodically to clear chips and prevent binding or breakage.