I want to create some bolts (and other things) that have threads. It is easy to make a profile of the bolts and then rotate it to get the correct shape, but it don't see how to add the threads. I'm sure that it has something to do with the helix but I can't see how to get the V shape of the threads.
Can someone help me?
Thanks,
Mark

Hi Mark, one thing to be aware of is that threads are a very small sized but tightly curved and detailed objects, so adding a bunch of them can hugely increase your model size and really bog things down a lot. So you don't want to have a whole bunch of them, but it is possible to do some small number of them for a zoom in illustration or something.

To create one you do start with a helix just like you were thinking - then you need to draw a triangle and then do a sweep with the triangle as the profile curve and the helix as the rail path, and set the "Twist" option to "Twist = Flat".

See these posts for some illustrations and step-by-step:
http://moi3d.com/forum/index.php?webtag=MOI&msg=767.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=490.36

- Michael

Screen capture of a variation.