Hi all, On testing the above on my Mac OS 10.6 I had the same problems. I did find if I enlarged the 1.5mm radius cylinder by 2 (to create a 3mm radius) I could create a simulated thread spaced at 1mm intervals. I then scale the cylinder back down (.5) to give me a thread spaced at .5mm.
I need to show this detail as the items are shown at a large scale. They are being used in instruction manuals.

Sorry! I did not see this topic had a second page. Dave R and Pilou have already covered this point. Dave R's point about using a copy of a component to do this task is a very good idea; Thanks Dave R.