Electronics for New Machine + Chinese Spindle + VFD

[mturneruk]

Just had my first oh shit emergency stop.

For some reason during a multipass cut of 18mm Birch plywood, the machine lost about 10mm in the Y direction during pass number 4.
I was cutting 4mm passes at about 1500 mm / per min.

As i was towards the end of the cut the cutter was already 16mm into the wood, so when the Y lost 10mm the cutter started to plow into the full depth plywood.

After slamming the Estop. I jogged the machine back to what should of been the Zero start point but the Y was 10mm behind where i started. The gantry still seemed square.

It buggered up my very nice piece of ply, but Jazzes Estop circuit worked perfectly! Anyone got any ideas what might of happened?.
I thought i set a fairly conservative feed rate / multipass depth to be honest.

Thanks
Martin