Hi Martin, also the screw threads tutorial on the Resources page that OSTexo mentions above will take you to his video tutorial here: http://vimeo.com/30765016

And also some previous discussions here on the forum:

http://moi3d.com/forum/index.php?webtag=MOI&msg=4623.1
http://moi3d.com/forum/index.php?webtag=MOI&msg=767.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=490.36

- Michael