Balax 12304-010 Thread Forming Sti Tap 10-32 Unf H4

Product Description

The BALAX 12304-010 is a thread forming STI tap designed for cutting 10-32 UNF internal threads in spark plug thread insert (STI) applications. Manufactured from high-speed steel with a bright uncoated finish, this bottoming-style tap features an H4 thread limit for precise tolerance control. With an overall length of 2.5 inches and a 1 inch thread length, it is suited for threading operations that require full thread engagement close to the bottom of a blind hole. Machinists and maintenance technicians working with STI thread inserts rely on this tap for accurate, repeatable results in production and repair work.

This tap is used in applications where stripped or damaged 10-32 threads are being restored using STI helical inserts, or where new STI-spec threads are being created in ferrous and non-ferrous materials. The bottoming chamfer allows threading to the full depth of a blind hole, making it appropriate for tight-clearance assemblies and repair jobs where depth is limited. It is commonly used in machine shops, aerospace maintenance, automotive service, and general industrial repair environments.

Key Features

• Thread forming STI design for use with 10-32 UNF helical thread inserts
• Bottoming chamfer for threading to full depth in blind holes
• H4 thread limit for consistent tolerance control
• High-speed steel construction for durability across ferrous and non-ferrous materials
• Bright uncoated finish suitable for use with standard cutting fluids
• BXSTI series with 0.255 inch shank diameter for standard toolholding

Compatibility

Designed for use in STI thread insert applications requiring a 10-32 UNF tap with H4 thread limit and bottoming chamfer. Compatible with standard 10-32 STI helical insert systems. The recommended 75 percent thread drill size for pre-drilling is 0.215 inches.

Installation Notes

This tap should be installed and operated by a qualified machinist or maintenance technician familiar with thread forming and tapping procedures. Always ensure the workpiece is securely clamped and pre-drilled to the correct diameter before tapping. Use an appropriate cutting fluid for the base material to extend tap life and improve thread quality. Do not force the tap if resistance increases unexpectedly, as breakage in blind holes can be difficult to recover from.