This 3/8" BSPF (1 1/2" OD) RH HSS split die is a hand and machine thread-cutting tool designed to restore or create external 3/8" British Standard Pipe Fine threads on rods, fittings and machined components. The split die form allows fine adjustment of thread fit by tightening or loosening the split, making it ideal for repairing worn threads or cutting new parallel BSP threads where a controlled fit is required.

Manufactured from M2 high speed steel (HSS) and supplied in a ground, bright finish with a corrosion-resistant black oxide coating on the body, this die offers long wear life and consistent tooth geometry. The tool produces the Whitworth 55° thread form used by BSP parallel (BSPP/BSPF) systems and is suitable for right-hand (RH) cutting. The die’s 1 1/2" outer diameter fits standard round die stocks and holders for both manual and machine applications. It is manufactured to work with common pipe-thread tolerances and is compatible with recognised pipe-thread standards (BSP family and associated BS/ISO guidance such as ISO 228-1/ISO 7 series where applicable) for interchangeability with mating fittings.

Typical applications include plumbing and pipework maintenance, hydraulic and pneumatic component assembly, instrumentation, marine and general engineering repair shops where BSP fittings are used. The die is effective on a range of materials including mild steel, brass, bronze, aluminium and plastics; for stainless steel or very hard alloys consider a cobalt alloy die or stepped cutting technique to prolong tool life.

Key benefits are the adjustability of the split design for accurate thread fits, the wear resistance and toughness of M2 HSS for prolonged cutting life, and the protective finish which reduces corrosion and stick-slip during cutting. The die’s compatibility with standard die stocks and BSP thread forms makes it straightforward to integrate into workshop tooling kits and service vans.

Duchy Fasteners stocks a broad range of dies and die sets across BSP sizes, with single items and multi-packs available alongside compatible die stocks and tap-and-die sets; please check our inventory for available sizes and pack options. (Product code: DIEPF0037)