This product is a 7/8" BSW (British Standard Whitworth) right‑hand split die, 2" long, manufactured in high speed steel (HSS) for cutting, repairing and sizing external Whitworth threads. Its primary use is to cut or restore 7/8" BSW threads on shafts, studs and bolts where the Whitworth form (55° thread angle with rounded roots and crests) is required, commonly during maintenance, restoration and fabrication work.

The die is produced from M2 grade high speed steel and is supplied in a bright, precision‑ground finish to present a sharp cutting profile and good chip evacuation. The 2" die length gives a longer engagement for improved alignment and smoother thread lead‑in. As a split die it features a radial slot and adjustment screw so the effective cutting diameter can be opened or closed slightly for trimming or obtaining a close fit, making it useful for wear compensation and fine adjustment. This is a right‑hand thread tool, intended for use in standard die stocks for hand threading and in low‑speed die heads where applicable.

The thread form conforms to the Whitworth (BSW) standard used in British imperial practice and is compatible with standard BSW gauges and mating components. Typical applications include classic vehicle and motorcycle restoration, steam and heritage engineering, agricultural machinery repair, toolroom refurbishment, and general plant maintenance where imperial Whitworth fasteners are encountered. It is particularly valuable where original specification threads must be maintained or renewed.

Key benefits of this HSS split die include superior wear resistance compared with carbon steel dies, the ability to make fine sizing adjustments via the split, and reliable compatibility with existing BSW components and gauges. The HSS material withstands repeated use and offers good resistance to work hardening on tougher steels.

Duchy Fasteners stocks a broad range of imperial dies and diesets, including 7/8" BSW in single units and multi‑packs, and can supply corresponding die stocks and adjustment screws as required. If you need other Whitworth sizes or complementary tooling, please contact our team.