PID loop-Retrofit old plasma cnc with air valve actuated z-axis low tech THC

Thanks I will look into that

Search google for servo tuning detailed howto, the first result should be it.

The wcomp component could probably control your real Z axis.
linuxcnc.org/docs/devel/html/man/man9/wcomp.9.html

Thanks, I saw your post servo-tuning, very nicely explained.

The plasmac.state.out did the trick! Chill.

Just a heads up that they still make Plasmas with a Z axis that skates along for HVAC thin sheet applications. but it sounds like you have got it going!
Very cool

Nice. It does indeed do a good job with pressing down warped sheet. But the drag does bother me a little

But I'm also quite happy that I got i working, now I only need to fine tune the servos. I was a bit confused about that but now I understand that the drives close the velocity loop and that the position loop has to be closed in Linuxcnc.

What still confuses me is that I can only apply very low P value. Now I have P=2.5 but when I go higher the motor starts to vibrate quite heavily. Since the standard setting and a lot of the P values I read upon in other posts are way higher it feels a bit low to me. And I have the feeling the motors are not running at full speed with this settings. My FF1=0.03 at the moment.

It is all quite new to me so I don't have a feeling jet for what could be reasonable.

Can anybody tell me this could be in the right direction?