Another plasma component...

Phill, you forgot this in plasmac_gcode.py

But I have it going now!

Thanks Rod, it is fixed now...

I thought this was pretty interesting and just says how much wisdom there is in this open source group that is leading to such a superior plasma controller here in the LinuxCNC Plasmac hub!

I finally got a couple of prototype parts cut today. Its taken me 2 days mucking around with post processors and the inevitable plasmac upgrades twice a day! Anyway, I took them to my neighbour next door to get folded on his brake press. He purchased a $100k table about 6 months ago with a Hypertherm Maxpro 200 inverter with HF start on it. He's been plagued by intermittent problems when cutting mild steel.

They finally worked out this week that the high frequency start is causing noise or voltage to go back through the ohmic sensing circuit while cutting and causing the electronics to fault. As soon as they removed the ohmic sensor wire, it was fine. I guess it triggers an unexpected probe signal or similar which faults the system. I told him that that is not possible on my home built system the way the plasmmac/Islander ohmic sensing circuit is designed because both sides of the ohmic sensing circuit are physically disconnected unless we are actually probing.

This has been a very expensive fault for him in terms of downtime and also quite expensive for the supplier who have replaced a torch and electronics boards that are probably damaged. Instead of fixing it the plasmac way, they are stuffing around winding the ohmic wire around a bobbin to help prevent the RFI. They are actually going to reduce the wire diameter so they can get more turns around the bobbin! Sounds like a workaround for a poor design to me!

Well Phill, Here s a plasmac kerf cross photo and plot. Worked OK. What signal should I plot to see the THC being disabled?

So now I am back at a desk I will add a few more comments. I will post a video video. I think you need to ignore ArcOK on a prolonged void crossing as I got a flameout when I tried to do that with a message about ArcOK being lost. Some machines have settings for expanded metal grates so maybe it can be left to run its course.

Also, I had some crap in the torch that shorted the ohmic sensor for the first time. The system went in an endless loop as soon as the torch started to probe and I had to kill LinuxCNC as I was flooded with errors about ohmic being on while probing. At least I learnt the purpose of the test button! If you press it and the light comes on with the torch in the air you have a problem that needs to be resolved.

Phill, the biggest issue I've had with kerf crossing is on inside cuts causing a massive dive at the end of a cut as the slug falls away so I think you have fixed that. Should also allow corners to be looped. The other one is where you want to sever a sheet and just let it run off the edge of the plate when it dives badly. I think the insid cut quality will improve with this feature.