Trapezoidal thread form

Common card · No. 377004

Trapezoidal thread forms are screw thread profiles with trapezoidal outlines. They are the most common forms used for leadscrews (power screws). They offer high strength and ease of manufacture. They are typically found where large loads are required, as in a vise or the leadscrew of a lathe. Standardized variations include multiple-start threads, left-hand threads, and self-centering threads (which are less likely to bind under lateral forces). The original trapezoidal thread form, and still probably the one most commonly encountered worldwide, with a 29° thread angle, is the Acme thread form ( 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, which had been the form of choice until then. It is easier to cut with either single-point threading or die than the square thread is (because the latter's shape requires tool bit or die tooth geometry that is poorly suited to cutting). It wears better than...

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