On Sunday 12 July 2020 22:44:05 Leonardo Marsaglia wrote: > > Currently - there is no way to adjust it. I do run the > > acceleration and velocity as high as I can. (on the emco it is in > > above 50in/s^2) I do have some math that calculates the following > > error of the shape (actual shape vs axis position) and decide how > > fast to run the spindle to get the tolerance I want. There should > > be some sort of trajectory planning - but that might be above my pay > > grade > > > > (mostly academic for me - just wanted to see how well it works...) > > Thanks for the feedback Sam. I'll have to dig in a little more to > improve what I've done surely, but I guess only for the jobs I need to > do from time to time the live tool is justified. I usually do 6 mm > lift cams but sometimes I need to reach 9, 10 and even 11 mm of lift > wich are almost dynamically impossible to turn with conventional > tooling. > I find trying to imagine the method intriguing, as I already have an offset module in use on the Sheldon, doing compensation for bed wear vs z position, something that can be done very cheaply in the 200 hz jog thread, but thats obviously too slow for this. No reason I couldn't map an offset vs spindle, usable at backgear speeds or maybe even in 1st gear direct. Something I could feed into the offset thru a sum2 from a lookup table based on a MOD of encoder by scale function for the table index. Something like a 240 tap deep lincurve, but can the pi4 handle that in real time. Doubtfull as I can see other timeing problems Despite the newer power supply giving me 40+ ipm at the x axis, I doubt the pi4 has enough processing power to pull that off. The ultimate limit would be reached by adding a base-thread, which I don't have now, because that sort of thing would need response at per encoder edge. That speed limit then would be the 1 kilohertz servo-thread write to the stepgen.
One might experiment to find what those limits are with a siggen module if it could be synched by a phase locked loop running at 6x spindle index. Since its default is 1 hertz, it might make more sense for testing to go to backgear and turn the spindle at 1/6th turn per second, increaseing the gain of the triangle until a following error occurs. And finding the minimum time for the phase-locked loop to stabilize the spindle speed before advanceing the tool into cutting position, I can imagine cutting a bolt head compatible with a 12 point box end wrench, but not the pretty flats Sam got. That would require running a sine signal thru an ABS function in real time adjusting the gain for flatness of facets. Since thats a floating point function, servo-thread at 1 kilohertz would be its speed limit. But is that speed limit usable? IDK. :( Middle of the night thought experiments, darned things cost me sleep but never get done... Ought to be a pill for that. > > El dom., 12 jul. 2020 a las 15:52, Sam Sokolik (<samco...@gmail.com>) > > escribió: > > Currently - there is no way to adjust it. I do run the > > acceleration and velocity as high as I can. (on the emco it is in > > above 50in/s^2) I do have some math that calculates the following > > error of the shape (actual shape vs axis position) and decide how > > fast to run the spindle to get the tolerance I want. There should > > be some sort of trajectory planning - but that might be above my pay > > grade > > > > (mostly academic for me - just wanted to see how well it works...) > > > > sam > > > > On Sun, Jul 12, 2020 at 1:32 PM Leonardo Marsaglia > > <ldmarsag...@gmail.com> > > > > wrote: > > > Excellent job Sam. > > > > > > One question to the list in general. How are you managing the > > > atenuation and phase displacement you get when you increase > > > spindle rpm using eoffsets? Other than increasing the speed and > > > accel of the axis I mean. > > > > > > I could cut cams with some success but I really can't follow the > > > shape > > > > and > > > > > the phase with the same success and that's why I'm building a live > > > > tooling > > > > > jig to cut at really low spindle RPM to avoid this effect as much > > > as possible. My particular problem is worse because all the > > > machining of the cams has to be aligned with a keyway in the > > > camshafts. > > > > > > El dom., 12 jul. 2020 a las 5:12, John Dammeyer > > > (<jo...@autoartisans.com ) > > > > > > escribió: > > > > So question. > > > > 1. would you post the G-Code that made that? > > > > 2. I take it virtually 0 backlash on the cross slide? > > > > 3. I was also impressed with how well the parting off went. > > > > Mine tends > > > > > > to > > > > > > > dig in. > > > > John > > > > > > > > > -----Original Message----- > > > > > From: Sam Sokolik [mailto:samco...@gmail.com] > > > > > Sent: July-11-20 7:39 PM > > > > > To: Enhanced Machine Controller (EMC) > > > > > Subject: [Emc-users] Because the hardware store was 4 miles > > > > > away... > > > > > > > > > > Right? Am I right? > > > > > > > > > > https://youtu.be/wv7mMS5xKks > > > > > > > > > > _______________________________________________ > > > > > 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 > > > > > > _______________________________________________ > > > 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 > > _______________________________________________ > 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
