Dimensions of a worm screw
Dimensions of a worm screw
http://www.mitcalc.com/doc/gear4/help/fr/gear4.htm
in addition to @ PL's info
You have this link on trace part
which allows you to get the right parts with all the normative ratings from Nozag
http://www.tracepartsonline.net/(S(b4iyg33cml355wkw5i4ms2so))/partdetails.aspx? PartID=32-24012006-067831
@+ ;-))