MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
The trapezoid in the library doesn't follow any standard, you can tweak the shape by adjusting the offset-factors in lines 34-40 (last numbers (-0.4, 0, 0.1, 0.5, -0.5, -0.5, 0.5))
Measurements are in [mm], you'll have to look up the specs for 2"UNF.
Use "difference" to substract the thread from your model, the diameter of the substracted thread has to be bigger though.
cylinder(d=80, h=15, $fn=6);
translate([0,0,-5]) cylinder(d=54, h=25);