us digital encoders with a capacitor across dc+and- works without a fault....
El dom, 19 sept 2021 a las 2:49, John Dammeyer (<jo...@autoartisans.com>) escribió: > Over 10 years ago I bought two of these for the XY axis of the mill. > > https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor > > Also from US Digital the 250 line encoders. > I had assembled HP_UHU kits and had on standby the Henrik Olsson > replacement PIC processor modules although this photo shows the original > processor. > http://www.autoartisans.com/mill/HP_UHU_Modified.jpg > > One of the things that showed up right away was that with identical drives > one motor ran hotter than the other. Further investigation showed the > resistance of the windings was different with the warmer motor having the > lower resistance and inductance which matched the spec sheet. By then it > was too late to return the high resistance one so I decided to put what > appeared to be the on spec motor on the Y axis since it had to carry more > weight. The X axis got the cooler and higher resistance motor. > > When I finally got it all together I had a lot of position errors and > Henrik convinced me to trash the US Digital encoders which appeared to be > losing counts and replace them with the CUI. Changing to Henrik's module > improved things and positioning was now reasonably accurate. Until a short > while ago on the X axis. > > I pulled the encoder off remounted things and the problem seemed to go > away. Well last week, after the center drilled holes were off from where > the 1/4" drill bit went down I realized the problem had returned. After > much mucking around it seems that the real issue is still with that X axis > out of spec motor. > > What I did is swap motor+encoder from X <=> Y. The cumulative position > errors on X are now gone so that shows the HP_UHU drive was not the issue. > What's really interesting is the heavier Y axis now regularly faults at 140 > ipm where before the other motor could do 150 ipm. > > Also interesting when I drop the speeds to below 130 it doesn't fault but > I started seeing position errors. > > The G-Code test program > G01 X0 Y0 F60 > X-4 > Y-1.1 > Y0 > X0 > Y-1.1 > Y0 > X5 > And so on for about 5 cycles. > > Now the X axis returns to 0 every single time from either side of 0. But > the Y axis accumulates -0.020 or so error every time the program runs just > like X used to with that motor. Always only negative values. So strange. > > Also when that motor was on the X axis the sound of the system when > changing direction was clunky sounding in one direction and not the other > under G-Code. The change direction with jogging keys wasn't like that. > > I don't think it's worthwhile to spend the time to figure out what's > wrong. Seems pointless to continue to use a motor that isn't up to spec. > Probably better to just install one of the Bergerda AC Servos I have here > that I was saving for the Ball Screw upgrade. Especially since > AutomationTechnologies wouldn't replace the motor even though it was > clearly out of spec. Not about to buy anything else from them. > > John Dammeyer > > > > > _______________________________________________ > 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
