I am at a loss and don't know enough about EMI and/or grounding loops to troubleshoot my issue properly, and I am hoping someone has something I haven't tried.

I have a X-Carve (kind of), I am using the X- Controller on an upgraded rail kit from https://cnc4newbie.com. Just upgraded to a 2.2 kw, 220v, water cooled spindle with VFD. The 220 line is separate from the power source for the X-Controller board. It's all household, single phase.

Here is the issue. Once I got everything installed, it works ok a couple times. Then it started disconnecting from the computer mid carve. At this point, the second I push the run button on the VFD, the connection is lost.

Here is what I have done to troubleshoot:

1. Replaced all the wires to my steppers with shielded wire and grounded them all together to a GND terminal on the X-Controller. (only one end was grounded.)
2. Tried the X-Controller plugged into different power outlets.
3. Un-Plugged ALL the Steppers from the board. Only the grounding of the shielding wires were connected.
4. Grounded the CNC frame to the VFD Ground.
5. Tried grounding the CNC frame to the X-Controller.
Also I replaced my USB cable with a dual choke, shielded cable.

All the scenarios above resulted in lost connection

The only way it stays connect is as follows:

1. All the wires are disconnected from the X-Controller. (So only the Power and USB) or.
2. All steppers and grounding connected to X-Controller but the spindle is removed from the mount and not making connection to the CNC Frame.

I am thinking the aluminum frame of the CNC rails and gantry are somehow amplifying the EMI? Perhaps its a grounding issue, but I have tried grounding the CNC to different grounds. I don't think I have any ground loops.

Help.. I am hitting a wall!!!