i want to be able to 'zero' or 'set' my G54, G55, G56, ect. from within a single program. specifically my 4th axis 'zero'

i am machining multiple features around the circumference of a part and want to just index the part incrementally, zero the 4th axis and continue to machine the feature in absolute

please try to keep any help relatively simple as i am fairly new

fanuc 31i