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British Standard Whitworth(BSW) is an imperial-unit-based screw threadstandard, devised and specified by Joseph Whitworthin 1841 and later adopted as a British Standard. It was the world's first national screw thread standard, and is the basis for many other standards, such as BSF, BSP, BSCon, and BSCopper. History.
British Standard Pipe ( BSP) is a set of technical standards for screw threads that has been adopted internationally for interconnecting and sealing pipes and fittings by mating an external ( male) thread with an internal (female) thread. It has been adopted as standard in plumbing and pipe fitting, except in North America, where NPT and ...
Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. [1] " Nominal" refers to pipe in non-specific terms and identifies the diameter of the hole with a non-dimensional number (for example – 2-inch nominal steel pipe" consists of many varieties of steel pipe with the only criterion being a 2.375-inch (60.3 mm) outside ...
Sizes that may interchange, depending on the precision needed, include 2 mm (close to 5 ⁄ 64 inch (1.98 mm)), 4 mm (close to 5 ⁄ 32 inch (3.97 mm)) and 8 mm (close to 5 ⁄ 16 inch (7.94 mm)). In reality, a wrench with a width across the flats of exactly 15 mm would fit too tightly to use on a bolt with a width across the flats of 15 mm.
These drive fittings come in four common sizes: 1 ⁄ 4 inch, 3 ⁄ 8 inch, 1 ⁄ 2 inch, and 3 ⁄ 4 inch (referred to as "drives", as in "3 ⁄ 8 drive"). Despite being denominated in inches, these are trade names ( common product name ), and manufacturers construct them to 6.3 mm, 9.5 mm, 12.5 mm and 19 mm, having been rounded to a ...
The design was first proposed by the British Association in 1884 [1] [2] with a thread angle and depth based on the Swiss Thury thread, [3] it was adopted by the Association in 1903. The Thury thread was different in that it went both positive and negative all the way up to a size of −20 which was 75.2 mm diameter by 8.23 mm pitch (p). The ...
Square head cap screws up to and including 3 ⁄ 4 inch (19.05 mm) have a head 1 ⁄ 8 inch (3.175 mm) larger than the shank; screws larger than 3 ⁄ 4 inch (19.05 mm) have a head 1 ⁄ 4 inch (6.35 mm) larger than the shank. [9] In 1919, Dyke defined them as screws that are threaded all the way to the head. [10] socket screw
In Japan, the male sizes are often designated as DTC-20, DTC-27, DTC-40 (discontinued) and DTC-45 corresponding to a respective screw head size of 3.2 mm, 4.6 mm, 6.4 mm and 7.7 mm; with the size of the screw measured across the widest portion of the mating part of the head. The most common sizes in use for consumer electronics are DTC-20 and ...