On Friday 05 March 2021 21:17:12 Feral Engineer wrote: > Thanks Gene > > My emco is running a pi 4 as well. Model b, 4gb. What kind of latency > figures are you getting on your servo thread? I find mine to be a bit > finicky unless I keep wifi off
About 12 u-s. Worst I ever recorded was 200 u-s after pokig around the planet with firefox for about an hour. But that is not as important as you might think as both x and z are now 3 phase stepper servo's so they haven't much to worry about even with bad latency because of the rubber between the stepper drivers, which are in the mesa 7i90HD interface card. So the servos are the coupling between the stepper driver and the stepper itself. The advantage is that it only uses enough amps from the supply to keep it running smoothly. So the steppers run zombie cool, and with near total silence. Watching it run a program is a bit like watching Casper The Ghost, its so quiet. I acquired this lathe with a broken compound, it fell over long before I got it and landed on the compound crank, bending the spindle a few thou from the sudden stop with a bison 3 jaw chuck mounted, which I've since reground and it all runs true now. So now a QCTP is sitting on a couple pounds of cast iron. I cut from the sprue of a white truck wheel, we make them here in Weston, holding the TP a its normal height. It is so solid there's very little tool chatter either. I don't miss the compound since Linuxcnc IS a better compound than it ever had, doing far more accurate angles. > Phil T. > The Feral Engineer > > Check out my LinuxCNC tutorials, machine builds and other antics at > www.youtube.com/c/theferalengineer > I've seen 3 or 4 of them. Decent stuff, > On Fri, Mar 5, 2021, 7:56 PM Gene Heskett <ghesk...@shentel.net> wrote: > > On Friday 05 March 2021 18:35:19 andy pugh wrote: > > > On Fri, 5 Mar 2021 at 23:31, Feral Engineer > > > > <theferalengin...@gmail.com> wrote: > > > > Can someone send me a copypasta of their spindle hal stuff? Pid, > > > > ff0,1,2 encoder feedback, all that? > > > > > > I don't actually run PID on my lathe spindle. I have some > > > moderately complex gear selection stuff going on, but otherwise I > > > just trust the VFD to do the job. > > > > I don't have a pid loaded in either of my machines that are running > > a vfd. The vfd is stiff enough it doesn't need fawncy controls. > > > > The only reason I have an encoder on the sheldon lathe is for G33.1 > > and G76 support. Both of those slave the z travel to the spindle, > > what ever its running at doesn't change more than 2% under cutting > > load for G76, and maybe 5% for a big tap doing rigid taping. G76 > > also slaves the x to the programmed G76 cutting depth. On the > > sheldon, a pwmgen feeds a spinx1 which controls the vfd. Not even an > > d/a except the spinx1 because I run the pwmgen at a rate thats above > > the bandwidth of the spinx1. > > > > You get far better results by properly tuning the vfd. OOTB they > > suck huge dead toads thru soda straws. With a pwmgen getting the > > speed signals from motions spindle output, that pwm fed to the > > spinx1 along with the dir signal, and a bit of hal sequencing, my > > Sheldon, turning at 100 revs in high backgear, and low belt > > position/speed, I can do a rigid tap move, and measuring the > > overshoot at the bottom of the G33.1 move, is .25 turns. That's > > with a nearly 40 lb 8" 4 jaw chuck mounted. Who needs a pid? > > > > That .hal file is attached. Cherry pick with my blessing. Sure its > > a rpi4 file, but its running a Sheldon lathe that after stripping > > the stuff linuxcnc doesn't need, and putting in decent ball screws, > > still weighs around 1350 lbs. > > > > Stay safe and well, John. > > > > Cheers, Gene Heskett > > -- > > "There are four boxes to be used in defense of liberty: > > soap, ballot, jury, and ammo. Please use in that order." > > -Ed Howdershelt (Author) > > If we desire respect for the law, we must first make the law > > respectable. - Louis D. Brandeis > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
