Have you checked to make sure your outlets are actually grounded. If you are in a garage type space and they added any plugs not everyone thinks to ground them, I have seen this sooo many times with the plastic boxes.
Just make sure you only ground one end… 
Not really, I’m not sure how to do that… I’ll check on the Internuts to find out, good suggestion!
Hey guys, by the way, I created a small instructable about how to build a water cooled 3D printing nozzle for your machines, the same way I did it for mine. I’ve been using it for a while now and I’m now sure it is reliable enough, so you can have a look here and build your own if you want, it’s super easy:
Hope it helps!
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Here, the hardware store sells a tester that plugs into an outlet and has a green led us the ground is good. IIRC, it was $10. Electricians and home inspectors use them.
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!
Hey Dui,
I love the instructable. I’ve been meaning to look into your water cooling solution, so thanks, it seems really doable and safe to me. My last water cooling project ended in a fried CPU, so I’m wary!
I also print with the volcano, but with the 1mm nozzle and 0.6mm layer height. It’s been ultra-reliable in terms of the head never clogging and the first layer never screwing up (non-heated bed, blue tape, and isopropyl each time). That spool goes around at a hell of a rate when it’s dumping lots of plastic down.
I have played with increasing the feed rate multiplier up to 150% with great results. If I go further than that, the print quality comes down. I guess that’s the point you want more heat.
Would you be able to share feed rates and temperature limits you’ve experienced both before and after cooling? I’m keen to see how far you can push it.
Cheers,
James
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Good going Dui and thanks for the super informative instructable, I am sure it will help and teach many people, including myself a whole lot.
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Good news guys, I think I’m on the right tracks, finally!
So, I spent quite a bit of time shielding everything I could: the electronics are in a metal enclosure, all the axis are grounded, the plasma torch is grounded, the power supply, motor wire, plasma cutter case, etc.
Unfortunately, I do not have a ground rod, and I cannot easily install one, the only way would be to call an electrician since I live in a residence who is pretty strict on what you can and cannot do. So I modified an electric extension chord to provide the best possible ground connection, event if it is not optimal.
Anyways, I made the following tests:
-Fire the plasma torch without having any motor connected: great success, I fired up the torch many times and could not manage to impact the normal working of the Arduino. So I was very excited at this point.
-Connected one motor cable: it was not working well, the torch caused the motor to stop running, but it was not making anything unusual on the Arduino side. I was a bit disappointed at this point, but then I found out that the motor case itself was not making contact with the shielding…
-Connected the shielding to the motor case: Seemed to work fine, I fired up the torch many times and could not manage to make anything weird, it didn’t seem to impact the normal working of the machine!
Unfortunately, I had to stop my tests because the place quickly went crowded with friendly curious neighbors, and I was a bit afraid of what would happen if anything went wrong while everybody was there XD
I haven’t event tried the double shielding of the motor wires yet, I was only using the single shielding, so I guess this is encouraging!
Next step will be to order more copper braided wire, I didn’t buy enough to cover all the motor wires. Then I’ll try to clean the setup a bit, make it more user friendly and if everything goes as fine as it did today, I think I should have a nice and reliable plasma cutter.
I’ll post some pictures tomorrow since I left my phone’s cable at work
So far, it’s been a good weekend!
Good! How did you find out you don’t have a ground rod?
Well, that was the easy part: I looked around myself and saw no ground rod anywhere. XD
What I meant was that I do not have a ground near my machine, sorry, I probably have a ground rod where the outlets of my house are connected too.
So, I’m just using the ground from the electrical outlets, I suppose there is a ground rod attached to it somewhere, but given how my house is made it must be pretty far, I guess 30 or 40 meters away. I did not find it.
Most residential uses the water main as a ground.
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I didn’t know that, but I had the idea to use it… unfortunately it was too far.
Couldn’t find anything remotely suitable close to the machine…
I will make things properly and ask for the electrician to come, here in China it costs peanuts. Plus our compound electrician is a big fan of my work, so he will be happy to see my plasma cutter XD
I ran into that while remodeling this house over the last couple of years. The previous owner had replaced a bunch of the plumbing with PEX in the crawl space, removing the old galvanized (though he thought it was too much work to replace the galvanized in the walls). Guess where the GFCI in the bathrooms were grounded? It turns out that PEX doesn’t conduct worth sh*t… I had to run ground wires vertically through the walls so I could tie them in to the house grounds coming out of the electrical box. But then I now know for sure what the electrical is actually like in this 97 year old house. It still had live knob and spool in most of the house when I bought it. 
That’s not the proper way to ground the wiring though. Everything should be grounded back to the panel, then from there to ground. My house was built in 1832, so I run into the same kinds of WTF wiring hacks too.
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Yay! It’s working guys, it’s finally working! Alleluia!
So, after a lot of hard work, I finally managed to get the plasma cutter to work properly with the MPCNC. It’s been quite a challenge, but now I’m pretty confident the MPCNC will run quite a bit more reliably.
So, what have I done?
-Shielded everything I could shield: all the motor wires are shielded. On the motor side, the motor body is attached to the wire shielding using some breaded copper sleeve. Then on the other side, the motor cables are attached to the control box using some shielded connectors.
-I’ve built a control box to secure all the electronics, including the power supply, the screen, the Arduino.
-All the chassis is grounded
-Plasma torch is shielded (don’t know if this is useful, but probably couldn’t hurt)
It’s been quite a pain to do this, especially since I’ve originally spent so much time on my wiring using RJ45 wires. Cutting and removing all those neat wires was heart breaking. But in the end, the new system turns out to be a bit cleaner.
So, I made a few tests, and as it turns out, I never had the slightest problem with the Arduino or the motors losing steps. So, problem solved!
The results on those pictures look like crap only because I had no way to secure the material in place. At some points the torch touched the work and moved it, ruining everything. But I don’t really care, my point was just to see if it the machine itself would work correctly, and it seems like it did.
So now, I just need to build some kind of cutting table, I’ve purchased some steel and will try to make one soon.
As usual, tons of pictures:
The electronics Faraday box:
[attachment file=45633]
The Common earth ground star center point. Not pretty but I’ll make it cleaner later:
[attachment file=45634]
The Z axis shielding and the torch shielding:
[attachment file=45635]
Motor shielding:
[attachment file=45636]
The MPCNC right after the test cut:
[attachment file=45637]
Test cut results:
[attachment file=45638]
[attachment file=45639]
The metal plate was about 1mm thick, it took something like 30 seconds to cut.
I still need to find the correct settings for the CNC speed and the plasma cutter air pressure/power, but this is probably the easy part.
I think warping during cut will be an issue, though. I may have to build a water table to keep the sheet cool while cutting. I’ll do some more tests to see if this is absolutely necessary.
Anyway, this is a huge step for me, I now have a real multifunction machine capable of 3D printing, CNC milling and plasma cutting with only 5-15 minutes to switch from one tool to another. Just need to try the laser cut feature and I think I’ll pretty much have everything I’ve dreamed of!
Thanks a lot to Ryan who made this possible!
6 Likes
Wowzers!
Congratulations on persevering. I can’t help but wonder what the heck the issue was. Did you do it in a step by step manor or just do it all at once? I’m wondering if just shielding the torch would have worked?
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Awesome. Applause!
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Just shielding the torch wasn’t enough. That was the easy thing so it was the first thing I tried. I think it helped a little, but I didn’t try it for too long since I was afraid the Arduino would die at some point (it kept on freezing/restarting).
Then, I tried with one motor only, using a shielded cable, but only connected to the electronic box and not to the motor case. Worked better, but still had some issues.
Finally, I attached the shielding to the motor case and after that, no more problems, it seemed to work ok. But with only one motor running it’s a bit hard to tell, because the axis doesn’t run very well without both motors. So I wasn’t absolutely sure it worked. At least the Arduino didn’t seem affected, but I wasn’t sure that it was moving properly.
At that point, I decided to make all the other wires, a clean electronic box, soldered all the connectors, etc. Even if it wouldn’t work, in the end it would still be more reliable than my original setup.
And last weekend, I made the first real test. Apparently great success, I could not manage to get the Arduino to bug or freeze no matter how much I started and stopped the torch. I think I’ve started it more than a hundred times and no freeze or issue whasoever.
Clearly the issue was electromagnetic bursts during torch start.
Also, I forgot to mention that I’ve converted my torch for pilot arc. This way it can start the arc even if the torch is far away from the plate (this didn’t help with the electromagnetic interferences, but the torch firing works no matter where it is)
Cool!
I love that you tested it along the way…and didn’t lose a board. Thanks for the details. I really hope I get to make one soon, my welding is getting better so this could really make for some cool projects.