Hello everyone,

I recently implemented a 1.5kW VFD spindle on one of my machines and everything works very smoothly, except for one problem occurring randomly.

It happens mostly during longer jobs, where everything is going well and the cuts are great, until the Z-axis of the machine suddenly drops, as if the idle current of the driver was going down to 0 and the Z-axis motor could no longer bear the weight of the spindle. The odd thing is that the driver doesn't give me any error, but my PC is unable to connect to it using the USB port (unknown USB device error). One thing I observed, is that the driver green LED is not blinking in sync with the other drivers anymore. The problem disappears if I simply switch off the power supply and put it back on again.

I'm using the Mk3/4 controller and 6.0A 256 motor drivers.

I highly suspect interferences because of the VFD, but all my cables are shielded and connected to the ground, the spindle as well. I also installed an EMC Filter in my VFD control circuit that didn't help much.

If anyone has a clue that could help me, I would greatly appreciate it!

Thanks