Ray, Amir,
I think this discussion may help sort out the confusion about Stop and Feed Hold. When Stop is used, it stops all the outputs like Spindle, coolant and pulse as soon as possible. But Mach is able to keep track of issued pulses to the axis. Servos are normally behind the pulse train being issued by Mach and is following it by the counts what we call "Following Error." So, when pulse train is suddenly stops, the servo which is slightly behind the actual issued pulses, will be able to take care of sudden stop. If the inertia is heavy and speed is high at the time of Stop, servo may overshoot a little and then will return back at the last commanded pulse count. Hence Stop should not result in lost steps if servos are used and not induced to the Fault mode. Definitely, stop being sudden, it exerts heavy thud on the machine components. Comments are invited.
Mahesh Vyas.