Hello Everyone,
I am trying to make a 3/8" threaded hole and to do so, I used a 5/16" to make the cut sweep however, I'm not getting satisfying results. I also uploaded the part file so you guys can take a look at. 
Hello Everyone,
I am trying to make a 3/8" threaded hole and to do so, I used a 5/16" to make the cut sweep however, I'm not getting satisfying results. I also uploaded the part file so you guys can take a look at.
What standard are you using for your thread form?
I updated your model quick and dirty to give something to work backwards from to further understand the thought process. Also make sure you are using proper thread size dimensions. it looks like your initial thread shape was larger than normal and therefore intersecting with itself as it traversed the helix.
Buy this:
and use it for anything like this.
your thread profile is underdefined. pick the midpoint of the thread base sketch and apply a pierce mate to the end of your helix. Also do this with your plane to get a true perpendicular view to the end of the helix rather than using a standard offset and making your sketch endpoints coincident since the don't actually intersect the curve. what is the reason for needing to model the thread vs. using a tap drill and threading after the fact?