Balax 10843-010 Thread Forming Sti Tap 4-40 Unc H3

Product Description

The BALAX 10843-010 is a thread forming STI tap designed for producing internal threads in pre-tapped or Heli-Coil-style insert applications. It operates by cold-forming threads rather than cutting them, which eliminates chips and produces stronger thread forms in ductile materials. Built from high-speed steel with a bright, uncoated finish, this tap is suited for shops and field technicians working with small-fastener thread repair or original threading in aluminum, mild steel, and similar materials. The 4-40 UNC thread size and H3 thread limit make it appropriate for close-tolerance work in precision assemblies.

This tap fits into bottoming tap applications where threads must be formed to the bottom of a blind hole. The bottoming chamfer geometry allows threading close to the base of the hole with minimal runout. It is used in general machining, maintenance and repair operations, and light manufacturing where 4-40 UNC threaded inserts are specified. The BXSTI series designation confirms its STI design for use with standard thread repair insert systems. Installation is typically performed by machinists or maintenance technicians using a tap handle or machine tapping setup.

Key Features

• Thread forming design eliminates chips and produces stronger thread forms in ductile materials
• Bottoming chamfer allows threading to the base of blind holes
• H3 thread limit supports close-tolerance fits in precision applications
• High-speed steel construction provides durability in general-purpose tapping operations
• Bright uncoated finish suitable for use with standard tapping fluids and lubricants
• BXSTI series design compatible with STI thread insert applications

Compatibility

Designed as an OEM-style STI tap for use in thread repair and insert applications requiring a 4-40 UNC thread form with H3 tolerance in bottoming configurations.

Installation Notes

This tap should be installed by a qualified machinist or maintenance technician familiar with tapping procedures and proper speeds for high-speed steel tooling. Always apply an appropriate tapping fluid or cutting oil before use and ensure the tap is driven square to the workpiece to prevent breakage. Power down and secure any equipment before performing threaded insert repair on installed assemblies. Do not use this tap on hardened materials beyond the rated capability of high-speed steel tooling.