I am having a problems with my lathe, it seems that i can not get the feed rate right in a g93. i'm cutting a simple d groove on the part using a t-cutter. My problem is that the spindle will fly when i don't have a x move with the c axis in the same line. And when i do have them in the same lines the cut looks like it jumps. Can anyone out there can help? Please!!!

thanks
rob