3 Nm is about 2.21 ft-lb so at 12:1 reduction I think it would provide about 26.5 ft-lb. For comparison, the Tormach microArc4 (harmonic drive with NEMA 34 stepper) claims to provide a maximum holding torque of 28 ft-lbs but they suggest using only half of that to avoid excessive wear. I don't know the reduction ratio for their unit. See https://tormach.com/microarc-4-4th-axis-38412.html
> -----Original Message----- > From: Gene Heskett [mailto:ghesk...@shentel.net] > Sent: Saturday, May 16, 2020 3:22 PM > To: emc-users@lists.sourceforge.net > Subject: Re: [Emc-users] Cheaper than normal FHA-25B > > On Saturday 16 May 2020 15:09:08 Chris Albertson wrote: > > > One interesting and fun option is to make your own cycloidical > > reduction. These are completely buildable on a CNC mill that can do 2 > > 1/2 D machining on mild steel. Unlike most other gears, these can be > > cut from plate stock with just an end mill. THey can be 3D printed > > too. > > > > See the wiki link below. In a real system, the purple and grey parts > > are made from sealed bearing units and you'd have two moving plates > > stacked 180 degrees out of phase so as to counterbalance each other. > > But the good points are (1) high torque, (2) very low backlash, (3) > > compact size, (4) very simple 2D geometry > > https://en.wikipedia.org/wiki/Cycloidal_drive > > There are 100 Youtube videos about people making these with 3D > > printers but they work better with metal. These have become popular > > with people building robot arms and robot legs but could also be > > driven with a servo motor and used as a rotational axis for a machine > > tool. > > > > In a machine tool application, you would place a rotational sensor on > > the axis and close the servo loop inside the controller. A cycloidal > > system can be back-driven (just like spur gears or timing belts) so > > they MUST be used in a closed-loop > > Which then brings up the need for some math. So how would one go about > getting from a 3 phase stepper motors holding power, say 3 NM to lbs/ft > at the output of a 12/1 cycloidal gear? > > Assuming zero losses in the bearings, which I'd guess at 5% if decent > bearings. > > Could that 3NM motor hold it, or even move it under cutting loads? > > > > > 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 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
