TL/DR,
include <tsmthread4.scad>; // 4-start TR20x4 leadscrew, 15mm long tsmthread(DMAJ=20, L=15, STARTS=4, PITCH=4, PR=THREAD_TRAP);
This is a fast and flexible thread-profile generator for OpenSCAD.
Also see /lib/dimensions for lots of references on screw thread profiles.
Known limitations:
Name Last modified Size DescriptionApache Server at burningsmell.org Port 80
Parent Directory - TR11X2-diagram.jpg 2019-02-01 19:19 15K tsmthread4-mk5-acme.stl makes one of these 3-8-10-flange-diagram.jpg 2019-02-01 19:19 27K tsmthread4-mk5-acme.stl makes one of these cpu-killer.png 2019-01-30 16:34 16K tsmthread4.scad 2019-01-30 04:38 31K calibration.jpg 2019-01-30 04:38 296K What a mess. tsmthread4-mk5-print.stl 2019-01-30 04:38 786K Example print, household object threads drillbit.png 2019-01-30 04:38 44K An example of an impossible thread profile tsmthread4-mk5-npt.stl 2019-01-30 04:38 2.4M Example print, 1 1/2, 1 1/4 NPT fittings tsmthread4-mk5-acme.stl 2019-01-30 04:38 1.1M Example print, TR11x2 and 3/8-10 leadscrews thread-compensation.png 2019-01-30 04:38 15K What comp_thread does - better fit with less undersize npt-profile.png 2019-01-30 04:38 14K Calculated profile vs perfect triangles profile-test.jpg 2019-01-29 20:53 43K all-threads.jpg 2019-01-29 20:53 96K