What Are The British Standard Whitworth (BSW) Of Fastener?

What Are The British Standard Whitworth (BSW) Of Fastener?

Postview: 766       Date:March 7, 2024

The British Standard Whitworth (BSW) is a set of imperial-size thread standards for screws and bolts developed by Sir Joseph Whitworth in 1841. Whitworth threads were the world’s first national screw thread standard, designed for engineering and manufacturing purposes in Britain and eventually adopted worldwide in various applications. The distinctive feature of the Whitworth thread is its angle: the thread form is based on a 55-degree thread angle with rounded roots and crests.

Whitworth threads are specified by their pitch (the distance between thread peaks) rather than the more common diameter-pitch combination used in metric fasteners. The pitch is expressed in threads per inch (TPI).

Here is a table listing some common BSW (British Standard Whitworth) sizes for fasteners, including their nominal size (diameter) and corresponding TPI (Threads Per Inch):

Diameter (inches) Threads Per Inch (TPI)
1/16″ 60
1/8″ 40
3/16″ 24
1/4″ 20
5/16″ 18
3/8″ 16
7/16″ 14
1/2″ 12
9/16″ 12
5/8″ 11
3/4″ 10
7/8″ 9
1″ 8
1 1/8″ 7
1 1/4″ 7
1 3/8″ 6
1 1/2″ 6

Note: This table does not include all BSW sizes but gives an overview of some common dimensions. The BSW standard has largely been superseded by metric standards in many applications and industries worldwide, but it remains in use in some specific areas, particularly in older machinery, classic cars, and certain types of equipment. When working with BSW fasteners, it’s essential to use the correct tools and fasteners to ensure a proper fit and avoid damage.

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