Please see the attached picture, the purple threads (witch are internal threads). (the root of gray threads are another issue stemming from a known problem. please ignore!)
method of creation: Autodesk inventor (don't tease me, I hate inventor, which is probably why I am asking such a basic question)
5/8-32 un3A internal thread
1. create bore at nominal minor Diam (~.594")
2. draw 60deg triangle with .002" rad. the tangent to the rad is set to nominal major diam :.625"
3. use thread coil tool to cut threads at 32tpi
the tips of the threads look way out of proportion to me, and to make them look "correct" I modify the major diam to about 0.645". I dont' like what I dont understand!
any thoughts? It's been years since I had to actually model/design threads. HAve I forgotten something obvious?