Hi Joe:
Im not sure I understand the question. In LTurn you specify the stock diameter, and the drawing then specifies how much to remove.
The max diameter of the part should be the result more of the drawing than the program. Now it is possible that due to the roughing and/or
the finish-rough stage being set to too large a step it may miss some of the final diamter cut.. but that shouldnt be the norm.
If , for example, you specify one final finish-rough pass of .1mm ( or say .01") , then the final part should be within .1mm of the drawing final
diameter. Of course you probably see better than I since your using the program where some curves may be harder to cut exactly than others.
Minor curves, such as thoose in pens may have a arc radisu so large that even small roughing cannot really show the arc fully. Hopefully this winter
I will geta final finish pass working to everyones approval. Im teaching myself a great deal of calculus at the moment so by the time coding season
comes along I should be much better at intuiting the necessary steps Ill have to take.

Thx for the feedback, nice to see the program is being used,
Art