The 1/16" BSW RH HSS Split Die is a precision external threading tool designed to cut or restore 1/16" British Standard Whitworth (BSW) right‑hand threads on rods, bolts and studs. Its primary use is to form or clean external Whitworth threads in engineering, maintenance and restoration work where imperial Whitworth fastenings are required.

Manufactured from M2 high speed steel (HSS) and supplied with a bright ground finish, the split die is heat treated to give a typical hardness of around 62 HRC for long tool life and wear resistance. The die carries the 55° Whitworth thread form as used for BSW threads, and the split (slotted) body allows a small amount of radial adjustment for tightening or easing thread fit. It is a right‑hand cut (RH), designed for use in a standard die stock (hand holder) or with appropriate machine die holders for bench and lathe work.

Typical applications include model engineering, classic vehicle and motorcycle restoration, maintenance of older industrial equipment, marine and agricultural repairs, and any workshop needing to recondition or produce small imperial Whitworth threads. The 1/16" size is commonly used in precision assemblies, instrumentation and restoration projects where genuine BSW fasteners are required.

Key benefits of this HSS split die are its resistance to softening at cutting temperatures (red hardness) and its ability to maintain a sharp cutting edge for repeated use, which improves repeatability when forming threads. The split design makes the die adjustable for achieving correct thread fit and simplifies partial thread repair without the need to oversize the workpiece. While M2 HSS is not stainless, the bright ground finish and correct use of cutting lubricant minimise corrosion during use; for long term storage a light oil coating is recommended. The die is compatible with standard BSW gauges and die stocks used for imperial threading.

Duchy Fasteners stocks a range of imperial split dies and holders across common BSW sizes; the 1/16" die is available individually and in small packs to suit workshops and hobbyists. Contact us for availability and full size ranges.