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British Standard Whitworth (BSW) is an imperial-unit-based screw thread standard, devised and specified by Joseph Whitworth in 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 .
A screw thread is an inclined plane wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread. More screw threads are produced each year than any other machine element. [1] Threads are generally produced according to one of the many standards of thread systems.
BS 93:1951 — Specification for British Association (B.A.) screw threads with tolerances for sizes 0 B.A. to 16 B.A. BS 93:2008 — British Association (B.A.) screw threads — Requirements; The angle of the thread is 47.5° [4]: 2 and the depth of thread is 0.6 times the pitch with rounded tops and bottoms. Thus, the shortening at the crest ...
BS 92 Screw threads, British Standard Whitworth and their tolerances; BS 93 Specification for British Association (B.A.) screw threads with tolerances for sizes 0 B.A. to 16 B.A. BS 94 Watertight glands for electric cables; BS 95 Tables of Corrections to Effective Diameter required to compensate Pitch and Angle Errors in Screw Threads of ...
Many thread sizes have several possible tap drills, because they yield threads of varying thread depth between 50% and 100%. Usually thread depths of 60% to 75% are desired. People frequently use a chart such as this to determine the proper tap drill for a certain thread size or the proper tap for an existing hole.
Dimensions of a square thread form. The square thread form is a common screw thread profile, used in high load applications such as leadscrews and jackscrews. It gets its name from the square cross-section of the thread. [1] It is the lowest friction and most efficient thread form, but it is difficult to fabricate.
For example, 1 ⁄ 2-13 belongs to the UNC series (Unified National Coarse) and 1 ⁄ 2-20 belongs to the UNF series (Unified National Fine). Similarly, M10 (10 mm nominal outer diameter) as per ISO 261 has a coarse thread version at 1.5 mm pitch and a fine thread version at 1.25 mm pitch.
The standard designation for a UTS thread is a number indicating the nominal (major) diameter of the thread, followed by the pitch measured in threads per inch.For diameters smaller than 1 / 4 inch, the diameter is indicated by an integer number defined in the standard; for all other diameters, the inch figure is given.