Hypersensing questions

This looks more promising, and the "sometimes wet torch" can be fixed by adding a hal comp that will check the voltage at the probe signal and if it is higher than say 15v it would issue a pulse for the torch. Much better than having to do that manually.

Its good that the resistor llows you to clear the torch short by pulsing the torch.
Just reiterating. The purpose of the pulse torch button. Its to clear the torch of water...
Also the test ohmic sensor button is designed to test if there is a short in the torch tip. Pressing it should light up the ohmic button if its shorted.
So the workflow should be:
1. check sensor
2. Pulse torch if ohmic enabled
3. Run your job.

Everybody's environment will be different but on my torch with my town water + additive I got reliable sensing on a change of 0.1 volts before adding the resistor.

tommylight wrote: This looks more promising, and the "sometimes wet torch" can be fixed by adding a hal comp that will check the voltage at the probe signal and if it is higher than say 15v it would issue a pulse for the torch. Much better than having to do that manually.

Tommy, that is a good idea.
I did think that being able to pulse the torch via gcode might be handy too.
plasmac.torch_pulse_start seems to be the pin to toggle.
I think I'll leave that for others because I don't want to hack into plasmac too much.
To hook into a pin that is in use, you have to use or2 in hal so that the existing plasmac function OR your new function can trigger plasmac. Where I've done this, I've used unlinkp in my connections.hal first to avoid hacking any of the standard plasmac hal files.

I am not there yet, THCAD's are still wandering through Europe, all i got left are 2 faulty plasma cutters and none of them have shielding on the torch, a compressor that can not do over 4 Bar and the minimum for plasma is 5 so i have to open the plasma and short the under pressure switch, still waiting on the parts for the two machines i am building as today i got a call from the person who is working on that to let me know that he has NO mild steel sheets longer than 2 meters and i need some at 3 meters, got some small ALU parts but still waiting for the 125X44mm for the gantries on those two machines, etc etc......
But we do have movement ! I made two belt geared reductions today and attached to one of the machines so it moves, while it is still on it's back !
More at
forum.linuxcnc.org/show-your-stuff/38547...plasma-build?start=0
After i get some pictures and videos.

I did suggest a while back that we could do an automatic ohmic test before the first pobe on a job and if it is active the pulse the torch.

Maybe it wouldn't hurt to pulse the torch on the first probe on a job regardless but only if ohmic is enabled.

phillc54 wrote: I did suggest a while back that we could do an automatic ohmic test before the first pobe on a job and if it is active the pulse the torch.

Maybe it wouldn't hurt to pulse the torch on the first probe on a job regardless but only if ohmic is enabled.

So on first probe, do ohmic test, if probe is active, move to max Z height (to avoid any nasty piercings) and pulse the torch.

Its kinda what I do but on my machine, there is a knob to enable air flow so sometimes I'll flick it on to give it a good purge.

rodw wrote: So on first probe, do ohmic test, if probe is active, move to max Z height (to avoid any nasty piercings) and pulse the torch.

Something along those lines yes.

First probe would normally begin at home height, but it could be forced to max height to be sure to be sure.

[ramblings]
Could make it an ini file option or maybe a checkbox option in the Run panel next to the Ohmic Probe Enable checkbox. Not sure about pulse length as that may be a machine variable. But... I guess the only guys doing ohmic probing have quality machines as they require shielded torches. But... that will not always be the case as it is reasonably easy to set up an independent probe. Maybe pulse length in ini file, don't want Run panel too busy, it almost is now...
[/ramblings]