Bordo chrome alloy die nuts are designed for repairing, restoring, or forming external BSF threads—especially in areas where a standard button die cannot be used due to restricted access or on-site limitations. Ideal for maintenance, restoration work, automotive applications, and general engineering.

The BSF thread form, introduced in 1908 and specified in BS84:1956, is based on the British Standard Whitworth profile but features a finer pitch (more threads per inch). This provides a greater tensile stress area and improved resistance to stripping compared to coarse thread forms. Fine threads also offer better performance where wall thickness is limited or where short engagement length is required.

Key Features & Benefits

• Compact die nut design for threading in confined or difficult-to-reach areas
• Ideal for chasing, restoring, or forming BSF external threads
• Manufactured from durable chrome alloy steel
• Suitable for non-ferrous metals and plastics
• Finer BSF pitch increases tensile strength and thread engagement reliability
• Not suitable for high-precision or certified thread applications

Technical Specifications

• Size: 5/16"
• Pitch: 22 TPI
• Thread Form: BSF (British Standard Fine)
• Thread Angle: 55° Whitworth profile
• Standard: BS84:1956

BSF die nuts are widely used in automotive restoration, vintage machinery repair, metal fabrication, and precision mechanical applications where fine-pitch British threads are required.