The arcdroid dies when plasma starts

When i start a cut with the arcdroid it works until the plasma starts.
Then the controller hangs, restarts or resets, it does all three.
I am not sure what it does most often.
This happens a lot, like 80% of the time.
When it happens, the plasma continues to cut on the spot until the droid has booted up again.
Most times i need to just cut the power to the plasma.

What can cause this?
The plasma is a CNC configured plasma with pilot arc.

Thanks in advance.


Pretty sure you are dealing with high frequency interference. Pilot arc does not equate blowback start. Pilot arc is generally used for interrupted cuts like grating. You may well have a non compatible plasma cutter.

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Being a fellow european I was looking at both the expondo and stahlwerk ranges of affordable cutters but realised they were all hf, so I went with polish spartus that have reasonably affordable stuff with seemingly higher quality and all lf.
I went for the procut 45, haven’t yet got it tested though.

Here’s a link to spartus cutter range:

Good luck!


Thank you both for the input.

I tried to again use my Hypertherm MAX41, but it seems to be quite dead. last time it started 1 of 10 attempts, but now its dead.
Anyhow i started thinking what the difference was between the machines and the obvious difference was the copper sleeve around the hose and cables.
So i undressed the cables of the Stamos and put the copper sock around them.
I grounded the side closest to the machine to the machine ground.

Now it works and cuts reliably as it seems. but the plasma never stops when the cut is done.
The stop button on the pendant switches over to the green start button but the plasma still ejects the pixies.
I need to turn off power to the plasma to make it stop.
When i give the plasma power again it doesn’t start cutting (until i want it to).

Is this also a HF interference problem?
In my mind it is a relay in the droid that doesn’t release until the power to the plasma is cut.

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Doh!!! Hahahahaha. I am such a newb…
I had switched the plasma to 4t instead of 2t.

Je regarde le stamos cnc 125A pour utiliser avec un arcdroid . Vous avez ceci si j’ai bien compris . Est ce qu’il vous est possible de détailler avec des photos ce que vous avez modifier pour pouvoir travailler avec sur arcdroid . C’est ceci qui fera déterminer mon choix d’achat de la machine .
Merci d’avance

The handle.

The connector to the machine

So… I have not had time to play with this any more, so i don´t know how well it works in the long run.

But this is what i did. What is missing in the pictures is that i wound a thick copper wire around the sleeve close to the connector (machine side) and then run that wire to the machine ground. ( The electrical earth)

My french is very bad, so you will have to translate…

Merci pour le retour , vous pensez reprendre l’utilisation bientôt pour connaître un résultat récent ou pas du tout ? La tresse est sur toute la longueur de la torche ?

From my reading, running a High Frequency plasma cutter can cause damage to the Arcdroid, it’s also posted on the AD webpage…I’d get a non HF Plasma and resume…may get pricey if not


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Hi Petter,
have you been able to test the plasma in the meantime? Did it work?
Greetings for Germany

Hi everybody!
This week I received my ArcDroid and did my first tests.
I also have an Stamos machine from Expondo (85 CNC, with pilot arc).

After some successful test cuts I experienced problems. Running a program the arc will not be switched off after the first hole cut, the machine stands still. When the arc finally breaks or goes out, the ArcDroid reboots.
I tried to fix possible interference and plugged the power supply to a completely differently power line and made sure, that the ground wire hose assembly does not cross near cables of the ArcDroid. Now it is much better.

My setup was very quick and dirty improvised. Hoping that it is possible to avoid further problems, I will now make a proper worktable where I want to include good HF measures.

Thank you torulf for your pictures, I think the metals sleeve is a very good thing. I will definitely try that.

Do you guys have any tips what should I consider? What does perfect grounding look like?
The inverter casing has a extra grounding screw terminal. Should I run an extra 16mm² grounding to the main grounding rail of the building?
How should the arcdroid itself be treated? Of course, there should be no currents of any means, but as the device is made of metal and connected to ground by the power cable it is not possible to operate it completely isolated…

Greetings from Austria,

My research shows this is a High Frequency plasma cutter, Will cause damage to Arcdroid if so…I would stop trying until you can sort it out. see link

The text on the product page you found is a little bit confusing and generic, I doubt if all that is true.
The machine definitely works with pilot arc and not with HF ignition. Can use the torch as a lightsaber. :rofl:
Since the machine is explicitly intended for CNC applications, I assume that it should be possible to use it. Hopefuly… :slight_smile:

HF machine will have a pilot arc too …Best of luck, I hope you figure it out and get to having fun !


Hi Mike!

Are there different pilot arc systems? As I know, pilot arc is recommended for cnc applications, and the need a small internal ignition.
How does e.g. the Hypertherm machines start the arc?

I think the way to tell is see if the electrode is fixed or slightly spring loaded

Fixed would be HF

Here is a video to help understand

Hi there

Unfortunatly this is plama cutter uses an old style High Frequency Pilot to initiate the Arc so it is not compatible with the ArcDroid.
You should be looking for a plasma cutter that specifically states low frequency or is “blowback start”

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@Andrew This machine Mfg had specifications hidden quite well it seems, Perhaps there needs to be a list of DO NOT USE plasma cutters too?

I just wanted to add my latest experiences:

I have an Stamos 85 CNC and finally have a proper setup für it:

  • Propper Table with good grounding
  • I also added a shielding for the torch line with good grounding.

Since that I had absolutely no problems, the arcdroid works really fine.

Thank you @torulf for sharing your idea!

super interesting your feedback. I looked at the stamos for a long time and while I was thinking, a Jasic 80 came out second-hand. as it had all the required properties, I moved towards that.