On Wednesday, December 22, 2021 8:20:10 PM EST John Dammeyer wrote: > Here's a bit of an addendum with respect to the HGD_EWG version. The wheels > are mounted on an ellipse and as close as possible to each other. > http://www.autoartisans.com/harmonicdrive/HarmonicDrive-29.jpg > They are just close enough to create zero backlash across the opposite > wheels which hold the cup in the ellipse form. The center gear (100T 1.25 > module) is fixed to the frame and doesn't turn. The center shaft is fixed > to the cup and runs in 1" ID tapered trailer bearings. Eventually this > will be metal. > > The motor drives the outer cup which holds the bearings and you can see that > the pressure on the cup is now on the shallow part of the ellipse rather > than the peak resulting in way less tension on the cup. It's formed around > the gear in the same way a drive belt goes around a toothed pulley. So > proper involute teeth can be used or even rubber belt teeth forms. The > outer cup is located with bearings located in the output shaft so it all > stays concentric. > > Compared to the smaller internal wave generator which has some resistance to > turning this one can have the bearing cup spun with a finger tip and you > still can't hold back the output shaft. Ratio is 36:1 with the 70 and 72T > forms and direction is the same as the motor. > > This also turns more easily than Todds dual ring gear and triple pulley but > to be fair, I don't have any ball bearings or support structure on that one > yet.
This looks like a much better idea John. the cup is a tad too big, as you've more that the needed clearance for a successful tooth hop in the slack between the bearings. I still think you will get a more linear movement with triangular splines. > John > > > From: John Dammeyer [mailto:jo...@autoartisans.com] > > What I also found was that with the cup, (don't know about the belts), is > > that even a very thin cup flexes in a way that only the 3 bearings at the > > top of the ellipse contact the cup. The other two are redundant and the > > reason they are there is because the original designer I don't think knew > > any better. > > > > So although I printed a wave generator that used all the wheels I did some > > detailed inspection and I cannot see them ever contacting. The cup is > > different from the belt perhaps? Maybe the belt could be held in place > > by the extra wheels but the cup is way too stiff for that. > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > . 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, 1940) 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
