Heli-coil 04CBB Hand Sti Tap 4-40 Unc H1 Bottoming

Product Description

The HELI-COIL 04CBB is a hand STI tap designed to cut internal threads for screw thread insert (STI) installations in 4-40 UNC applications. Built from high-speed steel with a bright, uncoated finish, this tap produces the oversized STI thread profile required before a helical insert is driven in. It features a bottoming chamfer for threading close to the bottom of blind holes, three flutes for chip evacuation, and a thread limit of H1 for close-tolerance work. Overall length is 2 inches with a thread length of 11/16 inches. This tool is used by machinists, maintenance technicians, and field service professionals working on thread repair or new insert installations.

The 04CBB is suited for hand-tapping operations in both production and repair environments. The 4-40 UNC thread size and H1 limit make it appropriate for light-duty fastener applications in metal components where helical inserts are required to restore or reinforce threads. The bottoming chamfer allows the tap to reach threads near the base of a blind hole, which is a common requirement in close-tolerance assemblies. This tap is intended for use with a standard tap wrench and is sold individually.

Key Features

• STI thread profile sized for helical insert installation in 4-40 UNC holes
• Bottoming chamfer allows threading to the base of blind holes
• H1 thread limit for close-tolerance Class 3B fit
• Three flutes for effective chip clearance during hand tapping
• High-speed steel construction for durability across ferrous and non-ferrous materials
• Bright, uncoated finish with 2-inch overall length and 11/16-inch thread length

Compatibility

Designed for use with HELI-COIL and compatible STI-style helical thread inserts in 4-40 UNC applications. This tap produces the correct oversized thread profile required prior to insert installation and is not interchangeable with standard 4-40 UNC taps.

Installation Notes

This tap is intended for hand use with a properly sized tap wrench. Before tapping, ensure the workpiece is securely clamped and the correct STI drill size has been used to prepare the hole. Apply cutting fluid appropriate for the workpiece material to reduce friction and extend tool life. Do not use this tap in a power driver without appropriate torque control, as tap breakage can occur at this thread size.