Quote Originally Posted by Valben View Post
Allright so:
1) Installed EMI filters on power inlet of VFD and 24VD power supply power inlet. Twisted cable. Haven't installed a filter on the PC because the PC power supply has a built-in EMI filter.
2) The spindle body is grounded back via the connector.
3) Spindle cable shield connected to ground and removed from the drag chain (now not running parallel with the stepper motors cables)
4) Stepper motor cables shield connected to ground.
5) Replaced the USB cable with better quality with dual choke magnet.

The problem isn't solved, as soon as I start the spindle the PC blips and Mach3 indicates "USB device reconnected" and system becoming unstable.

I will do another test tonight replacing the PC with a laptop (I just need to install Mach3 on the laptop) and see if the problem is may be associated with the PC USB port.

After that I am short of ideas :-(
Valter
You don't have the VFD drive Shielded Cable this is where your noise is coming from if it is shielded then you don't have the shield Grounded correctly

The cable to the spindle 4 wire plus shield the Shield has to be Grounded at both ends

Your wiring needs to be much better than you have it