kEN,
Glad you figured it out.
That 30% of max is just a ball park figure. The motor torque decreases as the speed increases. So by reducing the
max velocity you are allowing some "headroom" so you have some torque left when cutting or in the case of a an X & Z
move ie; G01 X..Z.. F15 ( if one of the axes was able to go faster ) it would limit the move to the slower of the pair.
I am rather conservative and have my max velocity set at 50% on my lathe ( 60IPM vrs 120IPM ) since when threading for instance i won't
try cutting a thread at a feedrate where there is not enough torque to accomplish the task and that velocity just happens to get the max
power ( where speed x torque = power ) out of the stepper. Over time or via testing you will find what velocity and acceleration settings works such that YOUR motors won't skip when running a program. If you have a motor curve / spec sheet for the motor you will have some data to get you in the ballpark rather quickly.
Others may have a different opinion, but that's my nickle on it.

RICH