Do it yourself CNC machines can be never ... Standard threaded rod was used as lead screws, with some very well made anti backlash nuts. Acme thread would have been a better choice here, however ...
You can also specify your own trapezoid parameters. For ACME threads see acme_threaded_rod(). d1 Bottom outside diameter of threads. d2 Top outside diameter of threads. blunt_start If true apply ...