Whitworth bolts follow the British Standard Whitworth (BSW) thread form.  The Whitworth thread system became the first widely adopted standard for screw threads in the United Kingdom and had a significant impact on the industrial revolution.

Whitworth bolts have a coarse thread pitch and a 55-degree thread angle. The thread profile is rounded, and the distance between each thread crest is larger compared to other thread systems, such as metric threads.  The dimensions of Whitworth threads are specified in terms of the diameter and the number of threads per inch (TPI). For example, a bolt with a Whitworth thread specification may be described as "3/8 BSW," indicating a bolt with a 3/8-inch diameter and a certain number of threads per inch.

Over time, the use of Whitworth threads has diminished as metric threads became more widely adopted, especially in Europe. However, Whitworth threads are still found in older machinery, vintage vehicles, and specialised applications where maintaining historical authenticity is important.

We stock part thread and full thread bolts (often referred to as a setscrew). Finishes include zinc plated, and unplated self colour. The bolts are high tensile Grade R. Diameter sizes 3/16", 1/4", 5/16", 3/8", 7/16", 1/2", 5/8", 3/4", 9/16", 7/8", 1", 1 1/8", 1 1/4", 1 1/2", 1 5/8", 1 3/4"