Balax 12303-010 Thread Forming Sti Tap 10-32 Unf H3

Product Description

The BALAX 12303-010 is a thread forming STI tap designed for cutting 10-32 UNF internal threads in spark plug thread insert (STI) applications. Made from high-speed steel with a bright, uncoated finish, this bottoming chamfer tap is built for use in blind holes where threads must extend close to the bottom. The H3 thread limit provides consistent tolerance control for reliable insert fitment. With a 2.5-inch overall length and 1-inch thread length, this tap suits bench and machine tapping operations performed by machinists and maintenance technicians working with thread repair or insert installation.

This tap is used when installing helical thread inserts into stripped, damaged, or undersized threaded bores in metal components. The bottoming chamfer style makes it well suited for blind hole applications where a taper or plug tap cannot fully thread the hole. It is commonly used in production and repair environments across industrial maintenance, automotive, aerospace, and general manufacturing settings. The BXSTI series is purpose-built for STI insert preparation, requiring the correct STI-spec drill prior to tapping.

Key Features

• 10-32 UNF thread size for standard unified fine pitch STI applications
• Bottoming chamfer for threading to the bottom of blind holes
• H3 thread limit ensures consistent tolerance for thread insert fitment
• High-speed steel construction provides durability across ferrous and non-ferrous materials
• Bright, uncoated finish suitable for use with cutting fluids
• BXSTI series design matched to helical thread insert specifications

Compatibility

Designed for use in STI thread insert preparation applications requiring a 10-32 UNF bottoming tap with H3 tolerance; the recommended 75 percent thread drill size is 0.2140 inches.

Installation Notes

This tap should be installed by a qualified machinist or maintenance technician using a tap wrench or appropriate machine tapping setup. Always drill the correct STI-spec hole to the proper depth before tapping, and use an appropriate cutting fluid for the workpiece material. Secure the workpiece firmly before beginning and back off the tap periodically to clear chips. Do not force the tap if resistance increases unexpectedly, as high-speed steel can fracture under excessive torque.