Originally Posted by
sinha_nsit
Angelw does not agree with me, and I have not yet done further experimentation to verify what I believe, but this is what I think will happen:
It depends on the start X. If it is, say, X40, and the depth of cut in G71 is 0.25, then there would be two straight roughing cuts, the first at X39.5 and the second at X39. Thereafter, the step-removal pass of G71 would start, and the defined profile would be traced by the tool (assuming zero finishing allowances). If the depth of cut is, say, 1.0, then there would be no roughing pass, and the entire material would be removed in one pass. But, as I said, Angelw does not agree with me. So, I have to check.
If you have both types available, there is no reason to use type I at all. Type II has an additional advantage that it does not create steps in roughing. So, finish is likely to be better than type I. Therefore, even for monotonic increase/decrease in diameter, type II should be used.
Sinha