Todd, More after the paint on the screw heads dries. http://www.autoartisans.com/harmonicdrive/GearSide3.jpg
I hadn't tried that particular orientation of Tooth #1. But as you can see, within the limits of 3D printing my 3 alignment screw holes are designed along with the concentric center bore to duplicate the planetary gear assembly so that tooth #1 on both gears always line up. Before I pulled the screws and painted the heads I did re-assemble it in that configuration and the 101T ring gear slipped easily down onto the planets. I might still be out one tooth but the entire assembly rotates so much more easily now. I'll draw up an alignment jig that has pins that will go into the other end of the 3 mount holes on each planet and align them correctly. More later. John > -----Original Message----- > From: Todd Zuercher [mailto:to...@pgrahamdunn.com] > Sent: December-17-21 8:10 AM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Harmonic Drive > > Here is a better image with the clocking points marked on the pinions to > better illustrate what I mean. > > Andy, I think what you are describing is what I did with my first drawing > (with four sets of planets). When the rings have the same > diameter but different tooth counts, you have to fudge the module (and > probably the tooth profile) of the rings. (The version of > Freecad I'm using doesn't give me the option to mess with the tooth profile.) > With that set up all of the pinions would have the same > tooth counts. And in the case of a 1 tooth ring count difference, one of the > planet sets would have no phase shift and could be a > single gear double tall. But all of the others would have different shifts. > For a 3 planet the shift would be +1/3 tooth for one set and > -1/3 for the other set. This set up has exactly 1 tooth per spider rev > reduction. > > I dropped the identical ring size version when I discovered that making the > pinions 1 tooth different made up for the 1tooth > difference in pitch diameter of the rings, because I didn't like how the > fudged module rings were meshing with the pinions, and I > couldn't change the tooth profile to make it work better with the software I > was using. > > Todd Zuercher > P. Graham Dunn Inc. > 630 Henry Street > Dalton, Ohio 44618 > Phone: (330)828-2105ext. 2031 > > -----Original Message----- > From: andy pugh <bodge...@gmail.com> > Sent: Friday, December 17, 2021 10:43 AM > To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] Harmonic Drive > > [EXTERNAL EMAIL] Be sure links are safe. > > On Fri, 17 Dec 2021 at 15:27, Todd Zuercher <to...@pgrahamdunn.com> wrote: > > > > Andy, Initially I thought what you are saying about the pitch diameters > > needing to be the same was true. And that would be the > case if all the pinions had the same tooth count and size. But When I was > modeling it I found that if all of the module was the same > for all the gears, and adding one tooth to the output set, and the output > pinions, their pitch diameters still meshed perfectly. > > I think that whilst that will work in theory, getting it assembled right > would be a problem. > > With two ring gears with the same PCD but +1 teeth on one gear you can have > pinion pairs with equal teeth and a fixed phase offset. > These can be assembled in any rotational orientation (as long as they are in > the right place relative to each other) > > Also, with such an arrangement you can drive the pinions with a small sun > gear, for a second level of reduction. You just have to > make sure that the sun gear toothcount is divisible by the number of > plantets, and also that you drive the unshifted half of each > pinion (I think) > > > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is designed for > the especial use of mechanical geniuses, daredevils > and lunatics." > - George Fitch, Atlanta Constitution Newspaper, 1912 > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Femc- > users&data=04%7C01%7Ctoddz%40pgrahamdunn.com%7C4842da1f9f934e91441e08d9c1741eef%7C5758544c573f47cebee96 > c3e0806fb43%7C0%7C0%7C637753527048039153%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJB > TiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=jxrNeQMSLeIFw8UIaEbmsfbb61M1abPjoVKFmwCIRP8%3D&reserved=0 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
