On Monday 09 August 2021 22:49:52 Peter C. Wallace wrote: > On Tue, 10 Aug 2021, andrew beck wrote: > > Date: Tue, 10 Aug 2021 14:31:22 +1200 > > From: andrew beck <[email protected]> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <[email protected]> > > To: "Enhanced Machine Controller (EMC)" > > <[email protected]> Subject: Re: [Emc-users] Just a > > little rigid Tapping Clip. With peck tapping > > > > Andy can you think of any good ways to change acceleration on the > > fly? > > If you are using the limit2 component, changing Spindle accelration > is just a matter of changing the limit2.N.maxv value on the fly > > A bang-bang way to do this would be to feed the absolute value of the > spindle speed into the compare comp and use the compare components > output to select between 2 accelleration settings (with a mux2 > component) > > A more elegant way might be to use the lincurve component to map > spindle velocitys into acceptable accelerations > Another thought if I may. Think about that reversal in the time domain.
I've used a limit3 to good effect for that, as mux2ing its input makes for a waveshape we in tv engineering called a sine-squared, where max accel corresponds to zero speed, where steppers have max torque. So I have shaped the spindles decel/accel curve to better match what the capabilities of the Z motor moving the whole heavy head of the G0704 can do. Using another mux2 as a sample-hold, I hold the direction signal while grounding the input to the limit3, ramping the spindle speed down until its almost stopped, detected by a oneshot watching the encoder, when the oneshot recovers its stopped and the new direction is allowed thru to the spindle controller, and the limit3 is is reconnected to the desired speed and it ramps back up to speed, from +2500 revs to -2500 revs in about 400 milliseconds. But my present hal does this at a fixed limit3 speed. Its slow enough to let Z keep up. Then I saw that if I used a mux4 to switch the input to the limit3 based on the state of the knobs tally switches, I could run the motor very slowly when changing gears, so now I can change gears while the spindle is running so the new gear is meshed at about 30 motor rpms, silent, no gear grinding and no hand on the spindle turning it till the new gear meshes. And I can do it while its running wide open. And it is all in the .hal file, no special gcodes needed. This shaping of a reversal has also worked well on the Sheldon lathe, reversing a nearly 40 lb chuck at 100 rpms with an overshoot of .25 turns while not asking the vfd to damage itself. So another thought, and it works well for me. > > I could call a custom m code in my post processor if I had to. > > > > Or is it possible to increase the deceleration if under 1000rpm? > > Currently my spindle acceleration is running through a limit > > component > > > > On Tue, Aug 10, 2021, 1:45 PM John Dammeyer <[email protected]> wrote: > >> I agree it would be nice to change acceleration on the fly based on > >> the G-Code. The AC Servo on the spindle responds really quickly > >> so fast acceleration is really fast. Great for the tapping. > >> Annoying otherwise. > >> > >> John > >> > >>> -----Original Message----- > >>> From: andrew beck [mailto:[email protected]] > >>> Sent: August-09-21 5:17 PM > >>> To: Enhanced Machine Controller (EMC) > >>> Subject: Re: [Emc-users] Just a little rigid Tapping Clip. With > >>> peck > >> > >> tapping > >> > >>> Quick answer before I go out. > >>> > >>> Peck Tapping breaks the chip otherwise they can break taps. Eg > >>> tap m6 > >> > >> down > >> > >>> 30mm you might break it. But do it in two bites you should be > >>> sweet and rpm is 400. > >>> > >>> If I somehow work out how to know if g33.1 (rigid Tapping is > >>> active) and export that to a python script. Then I can change my > >>> spindle acceralation briefly and tap at 1000rpm with almost no > >>> over shoot. The spindle Vfd > >> > >> can > >> > >>> reverse in 120degrees currently at 1500rpm > >>> > >>> But that will take some coding I think. > >>> > >>> I can change acceralation on the fly with custom m codes and > >>> halcmd currently but need to to set it up to automatically change > >>> back and forth if rigid Tapping is active > >>> > >>> > >>> > >>> On Tue, Aug 10, 2021, 11:50 AM John Dammeyer > >>> <[email protected]> > >> > >> wrote: > >>>> Impressive. Lots of questions. > >>>> > >>>> Why did you make two passes? Just because? Seems like the > >>>> spirals > >> > >> could > >> > >>>> get caught and muck up the threads on the second pass. > >>>> > >>>> Was this steel or aluminium? > >>>> > >>>> What type of coolant are you using? > >>>> > >>>> Do you have an oil separator disk or belt and aeration to keep it > >>>> from getting smelly? > >>>> > >>>> I did my 10-32 tapping at 150 RPM. Still scary how fast it moves > >>>> up > >> > >> and > >> > >>>> down. > >>>> > >>>> John > >>>> > >>>>> -----Original Message----- > >>>>> From: andrew beck [mailto:[email protected]] > >>>>> Sent: August-09-21 1:20 PM > >>>>> To: Enhanced Machine Controller (EMC) > >>>>> Subject: [Emc-users] Just a little rigid Tapping Clip. With peck > >> > >> tapping > >> > >>>>> M14x2 spiral flute tap. > >>>>> > >>>>> Rpm 400 > >>>>> > >>>>> Pecking 15mm.total depth 35 > >>>>> > >>>>> I can turn main power off at the wall and it will re line up > >>>>> with > >> > >> tapped > >> > >>>>> threads so long as I leave it in the vice. > >>>>> > >>>>> That's so cool. Love linuxcnc > >>>>> > >>>>> Might try a m20 tap sometime. I have 7.5kw spindle. Be > >>>>> interesting > >> > >> to > >> > >>>> see > >>>> > >>>>> if it can push it lol > >>>>> > >>>>> https://youtu.be/6QX2Qm3I2Ak > >>>>> > >>>>> _______________________________________________ > >>>>> 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 > >> > >> _______________________________________________ > >> 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 > > Peter Wallace > Mesa Electronics > > (\__/) > (='.'=) This is Bunny. Copy and paste bunny into your > (")_(") signature to help him gain world domination. > > > > _______________________________________________ > 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
