On Tuesday 24 January 2017 01:11:40 Danny Miller wrote: > Dude, drop the 2-phase bipolar stuff and move to 3 phase! Or at least > DSP drives. > > http://www.ebay.com/itm/Nema-23-3phase-1-8N-m-255ozf-in-stepper-Motor- >57mm-frame-8mm-shaft-57J1285-658-/262562493149?hash=item3d21f1b2dd:g:fM >sAAOSwCfdXor7F > > http://www.ebay.com/itm/LeadShine-3DM683-3-Phase-Digital-Stepper-Motor >-Driver-20-60VDC-0-5-8-3A-NEW-/222183145504?hash=item33bb25c020:g:JU4AA >OSw0kNXg2ZV > > That's a programmable DSP drive. That's a great combo. 3 phase's > torque does not drop off until significantly later than 2-phase. They > run smoother and don't need dampening. Torque numbers are not > entirely equivalent since the 2-phase is typically limited by where > the high-speed torque drops off, not the base torque. There are > larger ones available. > > But programmable DSP drives alone do great things with 2-phase: > > http://www.ebay.com/itm/1PC-Leadshine-AM882-Digital-Stepper-motor-Driv >e-80VDC-0-1-8-2A-protect-function-/252635288934?hash=item3ad23c9566:g:M >UQAAOSwT6pVmTam > > You go through a setup, tell it to auto-tune for that specific motor, > and it's unlikely you'll ever have vibration issues. > > Danny > > On 1/23/2017 11:45 PM, Gene Heskett wrote: > > Greetings all; > > > > I see some "Nema 24" motors at quite reasonable prices showing up on > > fleabay, in fairly high torque ratings, so I bought one 10 days > > back, since I need a stronger one, with perhaps a damper on it on my > > x axis. I bought the 8 wire model so I can drive it in parallel > > where I ought to be able to get 3k rpms out of it. The mount bolt > > pattern appears to be a duplicated of nema 23, but the body is just > > a wee bit fatter, the shaft is double ended 8mm, and the whole thing > > looks like it will fit behind the new apron with about 5mm of > > clearance between the back shaft end and the face of the bed. So > > its perhaps 5mm longer than the double ended nema 23 rated at 235 > > oz/in in there now. > > > > So I need to locate a 20 tooth, 8m bore pulley before I make the > > swap. > > > > Now, I don't believe this is going to help with the resonance stalls > > I am getting at about 30 ipm, so I'm thinking of building a viscous > > damper to fit on the rear of this puppy. But unlike the ones on my > > hf micromill, which are long steel spools carrying a 2+ inch stack > > of heavy fender washers with elastomer sheets between the washers, > > which are true shock absorbers as the resonance is killed by the > > frictional losses as the washers walk on the talcum covered > > elastomer, but I don't have room for a 2+" stack of fender washers > > in this spot. 5/8" axially at best. > > > > I do have room for a larger diameter assembly on the back, so I am > > thinking in terms of a 1/2" thick by maybe 4" in diameter alu wheel, > > drilling in from the side at a low angle to put a couple set screws > > in to clamp it to the motor shaft, and knock down 1 or 2 of my 00 > > buck 12 gauge rounds, measure them, and bore as many pockets in the > > rim as I can fit leaving about 20 to 30 thou for the balls to move > > within the pockets filled with grease, and sealed over. A thin > > gasket to contain the grease, and a 1/8" thick cap ring with a pair > > of 0-80 cap screws into the fillets between the pockets should make > > a good torsional vibration damper. Or plow a groove for a 1/16" > > o-ring on the outside of the cap, and the inside radius of the cap > > ring on one side of it. Useing the o-rings would tend to make the > > grease self distributing, and the small clearance might even aid in > > the damping if I intentionally plow a shallow 3rd groove between the > > grooves for the sealing o-rings would further enhance the viscous > > losses of the grease moving back and forth between pockets thru that > > narrow passage. > > > > What do the vibration engineers in this crowd think of this idea? > > > > Cheers, Gene Heskett > Its amazing the papers one can come across from a google search. For instance, this one bears testing out:
<http://machinedesign.com/news/how-take-vibration-out-stepmotors> Look at the last wiring diagram. I may try this tomorrow with the small motor just for S&G. The theory is that it rotates the resting position by 1/2 of whatever the microstep angle is, with the real effect coming from there never being a condition where one winding is completely off. This should result in a smoother step whose absolute movement angle is more consistent from step to step regardless of the current setting, where with the upper two configurations, smoothness and equal angle per step performance is much more dependent on the current mapping in the driver matching the magnetic characteristics of the motor. I am going to put the nema 24 motor in but that depends on whether I had the great good sense to buy two of those 20 tooth pulleys, so I can bore the 2nd one to 8mm. It will be a bit under driven, the m542T driver does 4.2 amps peak at full song, but this motor says 4.5 amp rms for max twist. Might have to buy a heavier driver & toroid power tranny to feed it. This one is heating some feeding the M542T 46 volts at its full current of 4.2 amps peak. News tomorrow night maybe. Thanks Danny. 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
