Type I cycles require that there be monotonic increase or decrease in the part diameter, along its length ... Everybody knows that.
Type II cycles relax this requirement. Diameter can vary in any arbitrary manner.
The surface finish by type II cycles is better than that obtained through type I cycles, because type II cycles do not create steps during roughing operations, obviating the need for G70 (unless a finishing tool is desired to be used in the end).
Now the question:
Why use type I cycle at all, when type II also can be used for monotonic increase or decrease in diameter?
Is there any specific advantage in type I cycles which is not there in type II cycles?
Is there an example where only type I can be used?
Some expert machinist may have the answer.
Thanks in advance.