It seems to me a 5amp breaker would be too small for all but the very smallest of spindles, unless it feeds a power supply for example, although if it only trips when in a cut???
Is it possible to trace what the breaker is Actually feeding?
I assume this is a single phase machine? Otherwise I would have said you may have one phase out on an SCR drive?
What type of spindle motor is it?
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.