I have read this a couple of times and from what I can see is you think the G63 is a tapping cycle ? I have never used it but from what I can make out it isnt, it is actualy a G Code command to keep the feedrate as programed in the program my lathes use different codes one being m88 .What it does is stop the feedrate being altered by adjusting a feedrate potentiometer on the machine by mistake ,in other words if you program say F.5mm then no mater what, it feeds at that,hope that helps you still need to program the tapping cycle after the G63 then put G64 after youve tapped the hole and move away
mick