I built a CNC plasma cutter that is controlled by an arduino with grbl installed. The arduino controls the motor drivers: Y-axis: DM556, X-axis: TB6600, Z-axis: DRV8825.
I'm using a 24V 15A switching PSU as power source.
The limit switches are NO and switch to GND via an optocoupler.
The plasma cutter trigger is also switched with a relay behint an optocoupler.
Everything works great as long as I don't turn on the plasma cutter. Once I turn it on, the arduino crashes immediately and corrupts it so badly that I can only reconnect if I unplug and reconnect it.
The plasma cutter is a low-frequency with a pilot arc, it even says "CNC ready". Therefor I didn't pay much attention to shielding and avoiding EMI/RFI. Unfortunately...
Now my question is, where should I start? The electronics are in a metal case that is bolted to the frame and grounded (earthed) on the poweroutlet via the PSU mains wire, but I can organize this grounding better.
What are my best options? Ferrite clips on the GPIOs? Shielding the motor cables? Shielding the plasma cable? And what should I connect the shielding to so that I don't create a ground loop? To earth or to the GND of the controller? Can I do something with HF filters in the form of capacitors with a low Farad value? And do I only put them on the GPIOs or also on the motor power cables, even though they are galvanically separated?
I'm curious about your experience/advice!