Gene, I did a search on the part number to gave and, they look really good but cost $400 per axis vs about $60 for what I have. Yes, they are much better. Did you find a better deal?
Question for the group: Assuming that you need about 3NM holding torque, what will $400 get you if you want to use a servo motor? I'm thinking that these 3-phase closed loop steppers are more comparable in performance and price to servos than to cheap steppers. Anyone have a link to a source of small-size Chinese servos and matching drivers. Next idea... I looked up Gene's part and the motor/controler is sold as a set. I can see why. But I see I can buy a 3-phase stepper motor for about $100. So we pay quite a lot for the driver and encoder. I can buy a 1000 line encoder for under $20 and close the loop with a $4 microcontroller and three h-bridges. I've done this many times using DC brushed gear motors. (My use case is robotics but it's identical to a multi-axis mill.) On Sat, May 1, 2021 at 6:30 AM Gene Heskett <ghesk...@shentel.net> wrote: > On Saturday 01 May 2021 08:35:12 Thaddeus Waldner wrote: > > > So these are actual stepper motors and not 3-phase BLDC motors with > > step/direction input? > > yes, and while I said a step loss will stop them it has to exist for an > unspecified time frame. You can fasten them down, put a vice grip on the > shaft and turn them 1/4 turn before they error, they will resist > mightily and if you let go of the vice grips quick enough, they'll catch > up to a zero error and just keep on trucking. I can, creeping along with > my jog dials, run a carbide tipped tool into a stationary chuck jaw, and > when its found itself jammed, it shuts down the output drivers and > bounces about 10 thou clear of the chuck, all without damageing the chip > in the tool. The machine will obviously need re-homed as I have the > volatile option set in the .ini file. Thats a 25mm z screw, but my x > screw is only an 8mm, so while its wired I've deferred to the size of > the screw and the possibility of damaging it, and not tested it > similarly with its shorter, 2NM rated motor. That screw today seems to > be made of pure unobtainium, its half of one of a triplet I bought from > Stuart St. about 15 or more years ago to cnc the smallest hf mill. > > > I always assumed that it’s the latter, with the difference being lost > > in translation. > > So did I, but installing one, replacing a stepper that ran burn you hand > hot, and finding it stone cold after half an hour powered up but the > only move was homing the axis was quite the eye opener, the motors > holding current is determined by the encoder error. No error=not enough > holding currant to make feelable heat. You think its shut down, until > you try to turn it... > > [...] > > 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) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
