On Wednesday 02 June 2021 23:43:44 John Dammeyer wrote: > Thanks everyone, > > Played with P and D of the PID to change some of the motor parameters > to see if I could get rid of that harmonic noise that sometimes comes > up but only in one direction. Nothing helped. I'm of the opinion > that under load in one direction but not the other the 0.0137" > backlash is impacting the motion.
No doubt. 13+ thou is a lot. Ball screws are the answer. ACME nuts are a headache to keep adjusted, and because of their friction, quadruple the size of the motor needed. BTDT, PITA. > It gets a bit of momentum and then > the motor speeds up to catch up to it and then over speeds and has to > be throttled back and that's what's causing the noise. Only during > acceleration during that particular speed and in one direction. > > Ultimately either preloaded ACME nuts or ball screws should fix this. > Using Sooner John. It will make a whole new machine out of it. > G01 Y6.5 F35 from Y0 is nice and smooth and the Shumatech DRO matches > the PC DRO. G01 Y0 then moves back and the DRO still matches so I have > the backlash adjusted fairly accurately. > > I can do that from F10 all the way up to F150 and only during > acceleration in the one direction back to Y0 do I hear a tiny rumble. > And sometimes at around F30 to F35 it may make that stepper motor > harmonic type noise. But it's not reproducible every time. Motor couplings that are cut in a spiral might "get in tune" too as they are pretty springy in terms of rotational stiffness. Replacing them with the type with elastomer spiders might help. > Hey! Perhaps also tighten the gib on the Y axis to make it stiffer so > it will always loaded. I'll try that. > > John > > > -----Original Message----- > > From: Jon Elson [mailto:[email protected]] > > Sent: June-02-21 8:52 AM > > To: Enhanced Machine Controller (EMC) > > Subject: Re: [Emc-users] Servo Motor Tuning. > > > > On 06/02/2021 01:20 AM, John Dammeyer wrote: > > > I really don't know if this is the right forum for this question > > > but in working with the mill over the last few months every once > > > in a > > > > while the DC Brushed Servo Y axis makes this horrible noise like a > > stepper motor at the harmonic instability. Try turning P down a bit > > and see if that helps. Also, try > > different values of D, that changes the damping. it may > > only take a small adjustment to get rid of the oscillation. > > > > Jon > > > > > > _______________________________________________ > > 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 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
