On Saturday 27 May 2017 15:52:54 Chris Albertson wrote: > Hi, > > Has anyone here experience with this? > > I think these are new. I've seen them on some web sites and also > eBay. I can't find any good engineering information yet, like user > manuals or speed/torque plots but the idea is great.
I think so too. But I am so used to thinking in in/lbs, and have never seen a formula or a chart that converts Nm to in/lbs, so I've no clue if they might be usable for me. So what is 3Nm equ to? I haven't a clue if it would fit for the X drive on the Sheldon, and not hit the bed at 112mm long. It would awfull close, little or no room for paint. > > They are an integrated closed loop driver/controller and motor. The > feedback loop is done inside the motor. They are MUCH better at > holding torque at high speed than are normal steppers. More like a > servo but at much lower cost. The motor accepts DC power (about 36 > volts) and step and direction. Here is one example from eBay > > Building the driver into the motor is good. For closed loop control > the driver must be matched to the motor so you would always buy them > in pairs anyway. Placing them in one unit saves the need to run a lot > of wire and all the noise problems and lowers the over all cost. The > driver cane made simpler and cheaper because it does not need to be > general purpose, it just drive the motor with known inductance and > resistance. > > http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver.. >... > <http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver- >2-in-1-L112mm-3Nm-24-48VDC-CNC/192011640913?_trksid=p2047675.c100005.m1 >851&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D40130%26me >id%3Dbc8047bd176346b9a8fbf5703256f1ef%26pid%3D100005%26rk%3D4%26rkt%3D6 >%26sd%3D262565354603> > > I saw a youtube video demo of one of these that showed it holding > position. It was using almost no current and the motor was cool. But > then if you apply force to the shaft the current zooms up to counter > the applied force, like a servo Basically it IS a servo. There is an > optical encoder. The above web page has a block diagram. > > All the good info is in Chinese. Perhaps someone here is good at > technical Chinese. My wife can read only the very basic stuff and > Google translation is not so good. I think these are designed and > sold into the Chinese domestic market hence no US sales office or > English technical documents. > > This eBay unit is cheaper than a conventional setup. I think this > is the way things are moving I'm sure of it. That posted price is about $65 less than when I checked last. So the switchover will be considerably speeded up unless the freight eats the difference. And it does eat much of it at $38 freight from HongKong. That brings the per axis cost up to $126 for the 3Nm unit. 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
