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In mechanical engineering, the thread angle of a screw is the included angle between the thread flanks, measured in a plane containing the thread axis. [1] This is a defining factor for the shape of a screw thread .
Typically, many rifles use thread diameters in the range between 25–27 mm (0.98–1.06 in). [citation needed] Many older rifles from the first half of the 20th century use a thread pitch around 2 mm (12.7 TPI), while many modern rifle use thread pitches around 1.5 mm (16.93 TPI). Fine threaded systems intended for hand tightening typically ...
Whitworth's new standard specified a 55° thread angle and a thread depth of 0.640327p and a radius of 0.137329p, where p is the pitch. The thread pitch increases with diameter in steps specified on a chart. The Whitworth thread system was later to be adopted as a British Standard to become British Standard Whitworth (BSW).
The Thury thread form had the crests rounded at 1 / 6 p and the roots rounded at 1 / 5 p so the thread angle was close to 47.5° but not exactly. This was simplified in the BA thread definition by defining the thread angle to be 47.5° exactly and the thread form to be symmetrical with a depth of 3 / 5 p.
Each thread is characterized by its major diameter, D (D maj in the diagram), and its pitch, P. ISO metric threads consist of a symmetric V-shaped thread. In the plane of the thread axis, the flanks of the V have an angle of 60° to each other. The thread depth is 0.54125 × 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.
The thread form follows the British Standard Whitworth standard: Symmetrical V-thread in which the angle between the flanks is 55° (measured in an axial plane) One-sixth of this sharp V is truncated at the top and the bottom; The threads are rounded equally at crests and roots by circular arcs ending tangentially with the flanks where r ≈ 0 ...
The original trapezoidal thread form, and still probably the one most commonly encountered worldwide, with a 29° thread angle, is the Acme thread form (/ ˈ æ k m iː / AK-mee). The Acme thread was developed in 1894 as a profile well suited to power screws that has various advantages over the square thread , [ note 1 ] which had been the form ...