Lol.. I certainly love the electrics part more than the machining most of the time...
On Sun, Sep 19, 2021, 2:07 PM John Dammeyer <jo...@autoartisans.com> wrote: > Hi Sam, > See below. > > From: Sam Sokolik [mailto:samco...@gmail.com] > > > > I have never used servo drives that close the loop.. I have always had > > great luck with normal closed loop within linuxcnc. (cheap used amc > > drives) > > > > (Actually - I take that back - I have used the stmbl drives. so far only > > for a spindle..) > > > > This is of course using mesa analog interface hardware. > > > > The only time I had issues with encoder counting was when I thought I > could > > get by with single ended encoders going over 8 ft... > > > > Look at something like this.. 20000 counts per rev, 2 axis with 4000? > > counts per rev... (and the encoders came installed on the servo, single > > ended and I think they are us-digital) > > If I was missing counts during these complicated sync moves - you would > > certainly see it. > > > > https://www.youtube.com/watch?v=-4sKHBh6rDk > > > > (plus no 3rd party software to tune...) - Granted you have the drives > and > > are familiar with them - at what point do you give up? > > > > sam > > That's the question. One possibility to try is to grab 110VAC line > voltage. Put a bridge and caps on it and drive that motor with more than > the 105VDC power supply. I'll have to check if my transistors are rated > for the 165VDC rectified voltage and I really would rather have them be > 250V transitors. And then there's the filters on the board too. The UHU > circuit was originally for up to about 75V. The HP_UHU came about for > higher voltage drives; Just don't know if I built mine for more than > 125VDC although the circuit design parts are for 11A. > > I _have_ tried one these motors with the STMBL but could never get it > tuned and support from the designers was inadequate to help me so I gave > up. > > I'd rather be machining... > > John > > > > > > > On Sun, Sep 19, 2021 at 12:59 PM John Dammeyer <jo...@autoartisans.com> > > wrote: > > > > > Hi Rick, > > > It may also have something to do with the DC Servo drive electronics. > > > Although it's differential encoder signalling the design may have > internal > > > issues that are somewhat corrected by the Henk Olsson module. I had > both a > > > small electrolytic and ceramic capacitors right by the US Digital > encoders, > > > which BTW, have been discontinued for a few years. Perhaps that's why? > > > Issues? > > > > > > I swapped the X and Y motor/encoder pair and sure enough the problem > moved > > > to the Y axis along with now only 120 IPM instead of 150 IPM. Above > that I > > > get following errors. Given that this motor has a higher winding > > > resistance I'm going to guess it's not a 90VDC motor but is more > likely a > > > 180VDC motor that was shipped as a 90VDC. Maybe the loading > introduces > > > noise in one direction that fools the quadrature encoder. It's very > > > strange that the following errors are only in one direction. > > > > > > At $145US plus shipping, since Automation Technologies won't replace > it, > > > I'm going to cast a new mounting plate for one of the slightly smaller > > > 1.27NM Bergerda AC servos. They were destined for the ball screw > upgrade > > > (and I'd ordered the wrong size thinking they were the same torque as > the > > > DC ones). So we'll see. If the Bergerda does well on the heavier Y > axis > > > then problem solved. > > > > > > More as it unfolds. > > > > > > Oh I swapped motor/encoder sets between X and Y,and with the Y motor > > > running the X axis the test program that runs the table back and forth > no > > > longer has a slightly different sound between changing direction CW > > > compared to CCW. So it appears that's also on the motor and not > LinuxCNC > > > nor the MESA. And absolutely no errors in position on X. Only now on > the > > > Y instead. That lets the HP_UHU servo drive off the hook too. > > > > > > John > > > > > > > -----Original Message----- > > > > From: Rick Moscoloni [mailto:rmoscol...@gmail.com] > > > > Sent: September-19-21 10:12 AM > > > > To: Enhanced Machine Controller (EMC) > > > > Subject: Re: [Emc-users] DC Servo issues > > > > > > > > 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 > > > >) > > > > escribi?: > > > > > > > > > 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 > > > > > > > > > > > > _______________________________________________ > > > 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
