[mike sr1]

It only drops .040 approximately, it isnt very noticeable unless its cutting horizontally, then when the e stop is pressed the head will drop at the instant the brake engages, and it produces a nice gouge in the part.

This happens each time the e stop is used, I know it does this so I use the esc key to just stop the machine, but in z down that will let the head freewheel.

I will call Tormach today and see what they have to say about it, may just need to tighten the gibs a bit more.
If its not a common problem, then I would think it would be mechanical as the dro reads the same before and after the gouge.

I called Tormach and Roy said its normal for the z to drop somewhat when shutting off the power with the e stop on the series 3 machines.

He said it can freewheel (Z) if the power is removed from the motor (hitting the exc key) .

He suggested using the space bar to shut it down at the end of the line of code.