Rods "Spaceship" Scratch built Plasma Cutter build

tommylight wrote: How does it feel to be able to turn the machine on and go grab a coffee or lunch or sleep and come back and find the parts ready?
Mentally, that is the best thing with Linuxcnc, it just works.
Nice work.

Nice. There are still some bugs in plasmac. I'm not sure if Phill has fixed them in later releases but its nothing you can't live with!

Nice. There are still some bugs in plasmac. I'm not sure if Phill has fixed them in later releases but its nothing you can't live with!

Rod,
When was your last update and what are the bugs?
I know kerf crossing is not right but I haven't had any feedback about the result if the kerf crossing override is increased.
I am also not 100% happy with probing.

Cheers, Phill.

Phill, the biggest issue is endless Z axis loops on probing if the ohmic sensor is triggered before you get to probing height. This can happen due to warpage. Holding the material down flat allows it to probe correctly and continue.

An example where it occurred.


I think I have some video I'll send you.

Rod,
Yes, I got the video.

That is quite a bit of warpage...

If you decrease Ohmic Probes in the Run tab it will fallback to float switch quicker. I probably should rename the Ohmic Attempts

That does show why I am not 100% happy with probing.

Cheers, Phill.

The same warpage also happened further down the sheet. I don't think it respects your retries so it seems to continue indefinitely.

I don't think the float switch would work in that situation. If you watch again, you will see the material is pushed down a fair way and then the ohmic sensor takes a fair while on the upstroke before it breaks contact as the material springs up again. I think the float switch would baulk at that and give wrong results.

What would be good is if this happens a few times, the probe height was increased by say 10mm each subsequent attempt. To set it at 50-60mm to fix this would slow cutting down a lot.

rodw wrote: The same warpage also happened further down the sheet. I don't think it respects your retries so it seems to continue indefinitely.

I don't think the float switch would work in that situation. If you watch again, you will see the material is pushed down a fair way and then the ohmic sensor takes a fair while on the upstroke before it breaks contact as the material springs up again. I think the float switch would baulk at that and give wrong results.

On my probe test rig I got good results with float switch and light material. The probe up is only one offset count per period.

What would be good is if this happens a few times, the probe height was increased by say 10mm each subsequent attempt. To set it at 50-60mm to fix this would slow cutting down a lot.

That sounds like a reasonable idea.

I was thinking along the lines of an initial quick probe to find the approximate material height then use the Probe Height value to do any further probing. This height could be offset on the fly by the component from the THC motion during a cut. The problem here is that you may end up with a pretty high probe height due to warpage (I honestly didn't know that it would warp that much).

It may be better to get some input from John and Tommy and anyone else that has a fair bit of cutting experience to see if we can come up with a viable solution that suits everyone.

Cheers, Phill.