Hi,
sounds eminently practical.
I would recommend DMM or Delta (A2 series) servos, quality at very reasonable prices.
If you are just turning on a coolant pump then a PLC is not required. Mach4 has a PLC script built in
and a ladder logic module called PMC. With a motion controller with enough spare inputs and outputs
a hardware PLC is not required.
Gallil is superb quality but you are paying for a lot of capability that you don't need. A three axis Gallil will
set you back $2000. Gallil's strength is its superb feedback control functionality....which you aren't going to use.
An Ethernet SmoothStepper ($190) or a 57CNC ($150) or a UC300 ($150), even if you bought a flash breakout
board for $200, would still be vastly cheaper than Gallil. I myself have had Ethernet SmoothStepper for six years
and can attest to its build quality and reliability.
Mach has a PWM output that when paired with a breakout board with a filter to produce an analogue voltage
means you do not require a PLC to control a spindle.
I would save money on the Gallil and the PLC to give you budget for your servos and inverter. Who knows you
may save enough to be able to afford Delta A3 series servos?
Craig