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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 .
The half-angle (between the taper surface and the axis of the pipe) is arctan(1 ⁄ 32) ≈ 1.7899° ≈ 1° 47′. The standard for Nominal Pipe Size (often abbreviated NPS, which should not be confused with the abbreviation NPS for the straight thread form standard) is loosely related to the inside diameter of Schedule 40 series of sizes.
Please note that the correct way to calculate the angle is: The taper is the change in the size of the diameter as you travel down the axis of the taper. So, take 1/2 the change size (1.75") and divide that by 12", arctan of the result is 1/2 the included angle. So 16.5942899... is correct.
The rate of taper is 1:20 on diameter, in other words 0.600" on diameter per foot, .050" on diameter per inch. Tapers range from a Number 2 to a Number 20. The diameter of the big end in inches is always the taper size divided by 8, the small end is always the taper size divided by 10 and the length is the taper size divided by 2.
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 thread with an internal (female) thread.
In engineering, draft is the amount of taper for molded or cast parts perpendicular to the parting line. It can be measured in degrees or mm/mm (in/in). Consider the fabrication of a hollow plastic box, without lid. Once the plastic has hardened around the mold, the mold must be removed. As the plastic hardens, it may contract slightly.
The major diameter still extends to within 1 / 8 H of the theoretical sharp V, but the total depth of the thread is reduced 4% from 5 / 8 H = 5 / 8 cos(30°) P ≈ 0.541P to 0.52P. [5] This increases the amount of the theoretical sharp V which is cut off at the minor diameter by 10% from 0.25H to 7 / 8 − 0. ...
The included angle characteristic of the cross-sectional shape is often called the thread angle. For most V-threads, this is standardized as 60 degrees , but any angle can be used. The cross section to measure this angle lies on a plane which includes the axis of the cylinder or cone on which the thread is produced.