HI, I don't think the LinuxCNC control scheme is cascaded or nested. I would call it parallel.
The only backlash problem I can imagine is if the backlash causes the motor to dither trying to maintain position because cutting forces move the axis enough to cause the control to try to correct the axis position. Is the ball screw supported on each end? If it is, then, is it possible the screw has some stretch preload. regards Stuart On Thu, Jan 1, 2026 at 4:10 PM andrew beck <[email protected]> wrote: > hey guys > sam i just looked at that link you sent > > that looks pretty cool > > only thing is i don't know is if it will work to reduce the backlash issue > i am getting. I have about 0.10mm of backlash on each axis. half of that > is from the thrust bearings which is fixable with new bearings > the rest is from the ball nut i think and i am not willing to fix that > > but i can only try it. > > does anyone want to have a go with making a config like they did? one axis > would be best I am struggling to get my head around the different layers. > i probably need to write it all out or use a diagram or something. > > regardless i am sure i will work it out. just might take some brain cells > > > > cheers > > Andrew > > On Fri, Jan 2, 2026 at 4:54 AM Sam Sokolik <[email protected]> wrote: > > > This was also John k.. I would trust his solution. He is the one that > > came up with hal in linuxcnc... (Among other things). > > > > On Thu, Jan 1, 2026, 9:49 AM andy pugh <[email protected]> wrote: > > > > > On Thu, 1 Jan 2026 at 15:41, andy pugh <[email protected]> wrote: > > > > > > > > On Wed, 31 Dec 2025 at 22:14, andrew beck <[email protected]> > > > wrote: > > > > > > > > > just looking for a config example if possible for a mesa card from > > > someone > > > > > that has this nested PID loop setup. > > > > > > > > This may not be as effective as you would hope. Cascaded PID loops... > > > > > > Actually, what was done with the MPM jigmill wasn't a cascaded PID. > > > What was done there was to run a P + FF control based on the motor > > > encoder and an I control based on the linear scales. > > > > > > Then the two controllers were summed together to create a PID > > > controller, but with I using a different feedback source than P and D. > > > > > > -- > > > atp > > > "A motorcycle is a bicycle with a pandemonium attachment and is > > > designed for the especial use of mechanical geniuses, daredevils and > > > lunatics." > > > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > > > > > > > _______________________________________________ > > > Emc-users mailing list > > > [email protected] > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Addressee is the intended audience. If you are not the addressee then my consent is not given for you to read this email furthermore it is my wish you would close this without saving or reading, and cease and desist from saving or opening my private correspondence. Thank you for honoring my wish. _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
