Let me introduce to the awesomness of the BOSL2 screw module:
https://github.com/BelfrySCAD/BOSL2/wiki/screws.scad
This is amazing but the first time I needed to make a screw I needed to make one that used the NPT standard which this module still does not cover :)
alt Hacker News
This is amazing but the first time I needed to make a screw I needed to make one that used the NPT standard which this module still does not cover :)