Plasma machine setup with Proma SD

This is the LinuxCNC forum. You appear to be using Mach3 and Mach3-specific hardware.
We may be able to give vague advice, but you will get much better answers from the Mach3 forums.

And as far as i know Cut 50 has scratch start, not HV or HF/HV, so it will not work with anything except hand.
The other part of setting it up is: you need to remove the step/dir wires that go from BOB to Z axis drive and route them to the PROMA SD INput step/dir, then you need 2 more wires from the PROMA OUT step/dir to go to Z axis drive.
You also need to have the ground from PROMA power supply connected to the Z axis drive or BOB ground, or it will not work.
That is it.
Regards,
Tom

There is an easy way to test if it has a HV start, just fire the torch in mid air, net close to anything, if it starts a bluish flame, you are good to go, it will work.
If it needs to be touching the metal for it to start, it will not do.
Regards
I did check for proweld cut50l, it does not say anything about HF/HV start, or any start method.

tommylight wrote:

If it needs to be touching the metal for it to start, it will not do..

(Caveat: I know nothing about Plasma)

I think I have seen plasma machines on YouTube using touch-start.
Would it be possible to use a G-code subroutine to start the arc?

This might not be the ideal project for a beginner, though.

I think yes, it is possible, but i never did try it, and i refrain from giving info about things i did not try or test or work with.
It would require a spring loaded torch holder, and a routine that would send the torch down to sense the work piece, go up just a bit as not to completely clear the work piece, start the torch (while the torch is touching the work piece), move in the direction the cut needs to be made (still touching the work piece for a certain period of time), then move up to cutting height.
All this is theoretical, i have not tested it and i am not certain it will work.
That would require quite a bit of trial and error for finding the timings and feed speeds and cutting direction, since the latter would most probably require gcode editing for each cut.
Things i know for sure:
Scratch start plasma will not start if the torch is held in contact with work piece, so just plunging the torch and giving the torch on command will not work.
It requires the torch to make and brake contact with work piece so it sets a spark that will in turn ignite the gas.
They are very unreliable at starting the arc, most of the time needing several tries to successfully start.
Moving on,
High voltage start plasma are best for using with cnc machines as they produce less interference at start and it is easier to shield from it since it does the high voltage at 50 or 60 Hz.
High Voltage/High Frequency start plasma are most reliable at starting the arc, and most difficult to shield from them since they also produce High frequency interference at a massive scale at start. Everything has to be shielded, moved away as far as possible from the transformer and torch cable, grounded properly, even keyboard and mouse cables have to be extra shielded if they are closer to afore mentioned equipment.
Most importantly:
If in use for more than 15 minutes a day, proper power installation is paramount and should be treated with utmost care, they do consume enormous amounts of power. I have several that use 28KW of power at full tilt!!!
Regards,
Tom