Ok, so I just received most of the things I ordered. Turns out I made a lucky mistake while ordering the braided copper. They are actually bigger than what I thought I was ordering.
I wasn’t expecting those braided wires to be hollow either, I thought they were flat, but it turns out that it is possible to insert a wire inside, those are in fact copper sleeves!
So my new plan is to go for insane shielding. Basically, the wires I’ve ordered already have a double shielding (some kind of amuminum foil, plus a breaded sleeve). I will add the big copper sleeve on the outside of the motor wires, this way I should have a perfectly flawless coverage for the whole wire and be able to ground them in both start and end point. Kind of a triple shielding, with both inside shields connected to the Arduino box, and the outside copper sleeve connected to the motor (no problem here since the two shields are not in contact).
Also, I found out that I can insert the whole plasma cutter cable in one of the breaded copper sleeve. So I will try to shield this whole cable too, hopefully it should reduce the EMI emission at its origin. Of course, I will still have the EMI from the electric arc itself since I don’t think that this could be avoided, but I shouldn’t have to worry about inductance from the plasma cutter anymore if I’m not mistaken.
That will be a lot of work, but I think this shielding will be pretty badass.
First I’ll try with only one motor, and see if it works. I really hope so because otherwise I don’t think there is anything else I could do.
So, to recapitulate, my process will be:
-Shield the plasma cutter wire and see if it stills interfere with the Arduino (I guess it will, what I hope to see is that it will reduce the occurrence of this issue)
-Put the arduino in the metal enclosure, with its power supply and screen, as far as possible from the plasma.
-Test fire the plasma and see if it still interferes with the Arduino (hopefully, it shouldn’t).
-If this is a success, double shield one of he axis motors and try again to fire the plasma, still with the Arduino as far as possible from the plasma
-If this works, try to see if it still works fine while reducing the distance to plasma.
To summarize, it should look something like this:
[attachment file=43424]
If you have any other suggestion on either the test process or the shielding technique, feel free to help me!
