Hi Colin, nice job on the Tattoo machine, it looks like you are getting increasingly more comfortable building things in MoI!

re: Screw threads - in one sense you may be better off without these since little tiny details like this can tend to add a significant amount of weight and data size to your model. For example, I wouldn't be surprised if your model becomes something like 4 times as big in data size when you try to add these little details in.

But anyway, here is a basic approach if you want to give it a try.

To start with, get your helix and a triangle arranged like this:



Select the triangle and run Construct / Sweep, and pick the helix as the path curve. The helix should be positioned so that it is going up vertically along the world Z axis. Then inside of the Sweep options, you need to set the Twist: option to Twist: Flat - this will prevent the triangle from twisting around as it travels along the helix path. That will give you this shape:



This can now be boolean unioned on to your main bolt shape:



It is probably best if you make the triangle kind of punch through the bolt a little bit instead of trying to make it skim directly along the surface of the bolt. Like in this case, position the triangle a little bit to the left of the bolt body (inside of it). Otherwise if you try to make it skim right along the surface it is too easy for it to just barely skip a tiny amount away from the bolt which makes things more difficult to process for the booleans.

Hope this helps!

- Michael