This is a 7/16" BSW (British Standard Whitworth) right‑hand split die used for cutting and restoring imperial Whitworth external threads. The tool is intended for producing 7/16" BSW threads (14 tpi, 55° Whitworth form) on rods, studs and bolts and for cleaning damaged or corroded threads back to the correct BSW profile. The split design allows a small radial adjustment so the die can be set to cut a slightly undersize or oversize thread or to compensate for wear.

The die is manufactured from M2 high‑speed steel (HSS) with a precision ground cutting face to provide long tool life and consistent thread form. The Whitworth thread profile conforms to the traditional 55° flank angle used for BSW threads as defined in BS 84; this ensures compatibility with standard imperial Whitworth fasteners. The item is supplied in a round die body format suitable for 1¼"–1⅜" style die stocks and is intended for use in hand die stocks and compatible machine die holders. Use of cutting fluid is recommended when threading steel or stainless materials to preserve the tool life and achieve a clean finish.

Typical applications include engineering and maintenance workshops, classic vehicle and motorcycle restoration where original Whitworth fasteners are still used, marine and railway preservation, and general machinery repair where imperial thread forms are required. The M2 HSS construction gives improved hot hardness and wear resistance compared with carbon steel dies, allowing efficient cutting in mild and medium carbon steels and serviceable performance on some stainless grades when used with suitable lubrication.

Key benefits of this split die are its adjustability for thread fit, the durability and heat resistance of M2 HSS, and direct compatibility with established BSW fasteners and gauges. The split format also makes it easier to re‑establish damaged threads without removing significant parent material. For routine maintenance it offers a practical combination of accuracy and service life.

Duchy Fasteners holds a wide range of imperial BSW split dies and related die stocks and taps; sizes are available singly or in small multipacks — contact us for current stock and pack options.