On Monday, September 12, 2011 10:52:16 AM Dave did opine: > Gene, > > Are you happy with the MM-542 stepper drivers? > > Dave See the post I just made, replying to Brian re the conflict between ICR and lost steps, I will do some testing of that with a dial indicator in the next couple of hours. And because these small ones can still do 50 volts, I have been trolling the net looking for a higher voltage PSU, this one is a medical grade switcher good for 9 amps, or 12.5 with active cooling, at the same 28 volts the old 40 pound boat anchor made. It was $26 at allelectronics.com and while not advertised, is equipt with a small 5 volt supply too, and can be remote controlled, needing an enable signal from the 5 volts to bring the 28 volts up.
Too bad I wasn't able to find a 42-48 volt version. OTOH, I can break 1/4" carbide mills with this one when the spindle blows a fuse. ;-) In other words, there is yet another chapter to be written. > > To stick my oar in this water, I agree. Concise is nice, but when > > there are considerable variables to fine tune, the newbee can easily > > get lost, blinded by the seemingly endless joint errors. > > > > For instance, I just switched from a 4 axis xylotex card to a 4 pack > > of MM-542's. The xylotex don't do reduced currents when stopped, but > > the MM-542's can be set to drop to 50% current when idle. I found I > > had to reduce my MAX_ACCEL's about 30% all around, while maintaining > > a healthy headroom cushion of over 30% between the TRAJ settings > > (slower) and the AXIS settings (faster) in order to get rid of the > > stalls on reverse direction startups after an idle period. > > > > I came to the conclusion that the ramp back to full current was taking > > more than a step, and of course if the first step is missed, a stall > > is going to happen. So I had to slow down the accels as if the > > motors weren't getting full power. This was based on the fact that I > > could tap the keys after an idle period for a half second and get a > > stall, but a quickly repeated tap always ran normally regardless of > > which direction the tap was. On a per axis basis. Moving a > > different axis was a cold start and stall. > > > > I also found that microstepping at 16x ran much quieter but gave more > > joint errors compared to 8x, but again, reducing the ACCEL's fixed > > that. I can now run the logo in nearly the same time, and no joint > > errors are encountered at 150% feed rate of 22.5 IPM (same as before) > > so the slowdowns didn't seem to seriously hurt that. > > > > But the docs need to explain this in more detail for the newbee just > > bringing a machine to life for the first time. And it should include > > a sentence or so about drivers that do reduced idle currents and > > their effect on MAX_ACCEL headroom. > > > > I don't think I will turn the reduced current feature off as the > > motors reduced temps can be easily felt. > > > > As the driver enclosure is largely sealed (its heavy 1/8" and 3/16" > > alu plate) the heat buildup there is going to need a larger, say 8", > > fan blowing on the box to maintain a safe temp inside the box, but > > this should suffice for cooling as there is a big 120 volt, ball > > bearing "rotron" fan circulating the air within the box to encourage > > the heat transfer to the box panels, so the whole box gets warm > > without noticeable hot spots. At 2 hours uptime, I'd guess 15F above > > ambient without the exterior fan. > > > > Cheers, gene > > ------------------------------------------------------------------------ > ------ Doing More with Less: The Next Generation Virtual Desktop > What are the key obstacles that have prevented many mid-market > businesses from deploying virtual desktops? How do next-generation > virtual desktops provide companies an easier-to-deploy, > easier-to-manage and more affordable virtual desktop > model.http://www.accelacomm.com/jaw/sfnl/114/51426474/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://204.111.66.235:85/gene/> "It runs like _x, where _x is something unsavory" -- Prof. Romas Aleliunas, CS 435 ------------------------------------------------------------------------------ Doing More with Less: The Next Generation Virtual Desktop What are the key obstacles that have prevented many mid-market businesses from deploying virtual desktops? How do next-generation virtual desktops provide companies an easier-to-deploy, easier-to-manage and more affordable virtual desktop model.http://www.accelacomm.com/jaw/sfnl/114/51426474/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
