It looks like some people actually model the helical screw thread!! If you are doing this then make sure your supervisor doesn't see it!
While that kind of thing might be fun, it certainly adds no value beyond appearance. In fact, it uncessarily consumes your time, computer memory, and regen time. Keep it simple. For external threads, say a No. 4 Coarse (.112-40UNC-2A), simply create a .112 diameter protrusion. Then add a cosmetic thread (.112 dia) over the threaded length.
Likewise, for a blind internal thread, say a tapped hole with a No. 4 Coarse (.112-40 UNC-2B) thread, simply create a counterdrill (hole with drill angle at the bottom) with a 118degree angle. Then add a cosmetic thread (.112 dia) over the threaded length. Depending on how critical the depth is, you may not even have to model the drill angle. The latter method is preferred because of simplicity.
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