Heli-coil 04CPB Hand Sti Tap 4-40 Unc H1 Plug Chamfer

Product Description

The HELI-COIL 04CPB is a hand STI tap designed for cutting screw thread insert (STI) threads in preparation for Heli-Coil wire insert installation. Built from high-speed steel with a bright, uncoated finish, it cuts a 4-40 UNC thread profile to an H1 thread limit with a Class 3B fit. The plug chamfer geometry provides a moderate starting angle suited for through-hole and most blind-hole applications. With an overall length of 2 inches and a thread length of 0.6875 inches (11/16 inches), this tap is sized for compact fastener applications in metal components. It is manually driven by hand using a tap wrench.

This tap is used when preparing a tapped hole to accept a 4-40 UNC Heli-Coil insert, typically in situations where original threads are stripped, damaged, or where a stronger threaded connection is needed in softer base materials. It fits residential and light industrial maintenance, manufacturing, and repair applications where fine thread restoration or insert preparation is required on small-diameter holes. Machinists, maintenance technicians, and assembly professionals typically use this tool in bench work or field repair settings.

Key Features

• Cuts 4-40 UNC STI threads sized for Heli-Coil wire insert installation
• H1 thread limit with Class 3B fit for accurate insert engagement
• Plug chamfer for versatile use in through holes and most blind holes
• High-speed steel construction for durability in common metals
• 3-flute design for efficient chip clearance in hand tapping
• Bright, uncoated finish suitable for general-purpose tapping with standard cutting fluids

Compatibility

Designed for use with 4-40 UNC Heli-Coil screw thread inserts as an OEM-style STI preparation tap. Consult the Heli-Coil insert series documentation to confirm insert size and drill requirements before use.

Installation Notes

This tap is driven by hand using a standard tap wrench - it is not intended for power tapping operations. Apply an appropriate cutting fluid for the base material before tapping to extend tool life and improve thread quality. Clear chips frequently during tapping, especially in blind holes, to prevent tap breakage. Follow applicable shop safety practices and ensure the workpiece is secured before beginning.