looking for Nitram hey guys
just found this post and made a reply on it https://www.forum.linuxcnc.org/10-advanced-configuration/37353-dual-pid-loops-and-appropriate-pins-for-feedback-to-the-trajectory-planner-et-al?start=10 just wondering if anyone that was a part of this thread is still around. I know from my own experience that those of us that have been playing with linux for awhile start to meet lots of other linuxcnc guys I am in new zealand and i know the original poster marty (nitram) is from australia so thought i would see if i could get ahold of him cheers Andrew On Sun, Jan 4, 2026 at 6:33 PM andrew beck <[email protected]> wrote: > hmm > > just read the link again to the example posted further up the email chain > > yeah it's going to a sum component > > ok i understand this i think > > i will try hopefully in a couple of weeks > > cheers > > Andrew > > On Sun, Jan 4, 2026 at 6:29 PM andrew beck <[email protected]> > wrote: > >> hey stuart >> >> yeah the ballscrew is connected both ends. i think one end has the big >> angular contact bearings etc >> >> and the other only has deep groove ends probably (its much smaller than >> the driving end) >> >> on my other two cnc mills they have angular contact bearings both ends >> and the screws are stretched between them slightly with a tiny bit of >> preload >> >> >> hey guys >> >> i was reading the link that sam sent two and it looks like the two Pid >> loops are running side by side and then the outputs are added together >> before going to the servo drive >> >> would i be correct in thinking that they are using the "sum" component in >> linuxcnc to do that? >> >> if so this is getting pretty simple >> >> cheers >> >> andrew >> >> On Fri, Jan 2, 2026 at 3:07 PM Stuart Stevenson <[email protected]> >> wrote: >> >>> 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 >>> >> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
