Looking for a board to control CNC Plasma Cutter

dc42

Is the control of a plasma cutter similar to a laser cutter? How does the plasma device need to be controlled?

fall-apart-dave

Hello

Just on/off funciton, closing an opening a circuit... No no PWM or anything. There would never be a situation where I would need to automatically change the plasma stream on the fly by machine.

The Openbuilds black box has a relay specifically for this purpose. I guess I would need to add one on the Duet?

dc42

Does it switch power to the circuit, or does the circuit have a separate control signal; and if so, what voltage does the control signal need? If the plasma controller is a commercial unit, can you link to a datasheet for it?

fall-apart-dave

Hi. Thanks for a swift response!

The cutter is an RTEC P50HF, from R-Tech Welding in the UK.

I tried to post a link but the forum said I was a naughty boy and trying to spam it, so I've had to delete. Sorry.

There is a circuit diagram in the manual, on the page there.

The switch is a control signal, you wouldn't put a plasma cutter power feed through a button. I think the control is just looking for a ground, rather than a voltage.

EDIT

Link here:
https://www.r-techwelding.co.uk/plasma-cutter-r-tech-p50hf/

I guess I am wondering if the board is fairly resiliant against interferance, and how easy it would be to use for this purpose.
I'm aware that shielding and grounding will be crucial, the cutter has a dedicated earth for attaching to CNC benches etc. I'm an offshore Survey Electronics Engineer by trade so routing out and nailing down interference is very much within my day to day work, so the usual things like removing earth loops, grounded cable shielding, twisted pairs, and sensible cable routing will be employed.
I also wonder just how I would actually use a duet as it has a superior spec than that of the black box, but OpenBuilds has some driving software for the blackbox controller that is already delveloped and there.

I don't really want to reinvent the wheel, I tried that once with a 3D printer and ended up with, more or less, an Anet A8 with a fancy frame.

jay_s_uk

I've upvoted your posts so try posting the manual again. Should reduce the risk of it being flagged as spam

fall-apart-dave

@jay_s_uk said in Looking for a board to control CNC Plasma Cutter:

I've upvoted your posts so try posting the manual again. Should reduce the risk of it being flagged as spam

Thanks. Wouldn't let me add another post but it let me edit the post.

dc42

Thanks. There doesn't seem to be an external input to turn the plasma on/off, but the wiring diagram shows a "torch switch". To turn the plasma on/off, would you plan to use a pair of relay contacts in parallel with (or in place of) the torch switch?

fall-apart-dave

@dc42 said in Looking for a board to control CNC Plasma Cutter:

Thanks. There doesn't seem to be an external input to turn the plasma on/off, but the wiring diagram shows a "torch switch". To turn the plasma on/off, would you plan to use a pair of relay contacts in parallel with (or in place of) the torch switch?

Indeed no seperate plasma on/off as with some cheaper cutters. This one has an integral switch in the torch, with the wires incorprated into the Euro torch. So the plan would be to use a relay (as per the Black Box) to make and break this connection.

dc42

That should work. The fan outputs of all modern Duets have built-in flyback diodes, so they can drive relay coils directly.

fall-apart-dave

@dc42 said in Looking for a board to control CNC Plasma Cutter:

That should work. The fan outputs of all modern Duets have built-in flyback diodes, so they can drive relay coils directly.

Thanks

So, now just the question of if the extra expense and lack of well trodden path is worth the difference in performance!