Hi,
I have built a desktop 5 axis machine which has a Head/Table configuration. See attached pdf.
 When I try to run gcode to produce a simple dome (hemisphere) there are times when there's  no movement with the xyz axes, actually every revolution of the C axis.  The result is I get slow, very rough and erratic C axis motion.

My question is how does the rotary axis get it's feed information in this case?
I am trying to find a solution.
Can anyone help please.