Gene, 3Nm is about 425 inch pounds. Roughly 140 in oz to 1Nm
I went to school in the late 70's to early 80's and even then all the science and engineering classes used metric. I could not even tell you what 1g is in Imperial units but it is just under 10 m/sec squared. In theory freight is the same for any motor of about the same size and power. I'm looking for a motor to lift the Z-axis of a Harbor Freight minimill. Almost every conversion I have seen with the mini mill the Z axis has the worst performance. In the design I'm using the z-motor is geared down 2:1 which means it spins faster so lower torque. This may be the place use the closed loop 3Nm motor. I'll use a 5-pitch ball screw and 2:1 reduction timing belt drive. This means the motor sees 10 pitch or .0005 per full step. and then likely have to use 1/4 steps. The X and Y axis are pretty light weight, anything would work. On Sat, May 27, 2017 at 1:58 PM, Gene Heskett <[email protected]> wrote: > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
