[rodw]

I'm not saying anything. I just followed the Hypertherm recommendations in the document and a friend donated a very old "star" grounding point and set up my stepper motor cabling very carefully with noise in the back of my mind. Having 24 volt electronic controllers also helps as the higher voltage is less susceptible to noise.

[mactec54]

I am using a db 25 parallel port plug from pc to bob (not shielded) ..... I think my main problem is the torch.... if I can find a way to drain emi from it my pc will probably stop freezing


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This would have to be a shielded cable, this would be a good starting point, go for Double Shielded Premium D-sub 25 Position DB25 Male/Female Cables - Fully Populated, Double Shielded

Your Torch Grounding and connection should be as per the PDF

[mactec54]

Are you trying to say that there is a difference in grounding for emi and grounding for electricity? ..... and the must be grounded separately?


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Here is a video for you and anyone else, this is long it starts with the basics and you may get confused or you will end up with a great understanding of Grounding and what it means

https://www.youtube.com/watch?v=mpgAVE4UwFw&t=46s

[Bradnicent]

Will a plasma cutter with pilot arc be a better choice regarding emi? .... a recent google search reveals that it reduces emi ...

https://www.bakersgas.com/weldmyworl...plasma-cutter/



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[skrubol]

Pilot arc may still have HF start. I think it may be a bit easier to shield than non-pilot arc, as the return path for the pilot arc is in the torch head.
What you want is blowback start, which I think is always pilot arc. Blowback doesn't use HF, so much easier to deal with as far as EMI goes.

[Bradnicent]

What exactly is blowback and how does it work?


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[rodw]

What exactly is blowback and how does it work?

The arc is started by shorting the electrodes in the torch head then the air pressure "blows back" the contacts apart so the arc transfers to the material