Ah I see, that makes sense, thanks for explaining it m_c - I will test tonight!

I notice in mach 3 there is a field in which you enter the spindle speed you would like and another field which displays the actual speed. In my setup the actual field stays on "0" and has a yellow flashing "led" next to it. Am I right in assuming I would need some sort of sensor on the spindle to monitor the spindle speed and then display the result in mach 3? If so is this easy to setup?

Thanks,
Jim