Whitworth Fine Thread BS 84

The Whitworth fine thread is a British fine thread. Along with the Whitworth regular thread, it forms the standard for fastening screws and nuts in Great Britain. Designed and first introduced by namesake Joseph Whitworth (1803 – 1887), known as the father of thread norms, it was later included in the British Standards collection and can be found in the norm BS 84. For this reason, the official name for the thread is British Standard Fine (BSF), but it is still commonly known as Whitworth fine thread. While the Whitworth fine thread is still widely used in Great Britain, it has been replaced elsewhere by metric fine threads or the American Unified National Fine threads.

The Whitworth fine thread is an inch thread, with the pitch given in threads per inch. The flank angle of the Whitworth fine thread is 55°.

The thread designation arises from the official abbreviation BSF and the external diameter in inches, e.g., BSF 1/4″.

In the thread table for the Whitworth fine thread, you will find the external diameter and pitch measurements in inches and as metric values. If you want to cut a Whitworth fine thread yourself, then you must pay attention to the measurements for the core hole diameter. Dies and taps for the Whitworth fine thread can be found in our shop by following the corresponding link!