On Thursday, December 16, 2021 5:03:10 PM EST John Dammeyer wrote: > > From: gene heskett [mailto:ghesk...@shentel.net] > > Subject: Re: [Emc-users] Harmonic Drive > > > > On Thursday, December 16, 2021 1:10:30 PM EST John Dammeyer wrote: > > > A pencil line on both outer ring gears. The Blue 100 gear held tight. > > > Turn the Red Planetary cluster shaft and the Green 101 gear turns > > > slowly.> > > Sweet John. Can you show us a pix from the blue side? And are the top and > > bottom pinions the same tooth count with the difference in the outer rings > > only? > > > > Thanks John. I am encouraged to see if I can make a smaller one when my > > printer is working again. > > > > > > From: Todd Zuercher [mailto:to...@pgrahamdunn.com] > > > > > > > > 19tooth, 1.25module "should" be the right size sun gear for the 101/41 > > > > gear set, and 20tooth would be the one for the 100/40 set. > > Hi Gene, > As Todd mentioned, 100/40 for the blue and 101/41 for the green. > > Now that I've beveled the gears (should have been done while printing) they > no longer run into the other ring which I also beveled I'm not sure the > system is actually working. It seems like the 101/41 set wants to skip a > tooth every little while. But I don't know if that's because the spider is > too flexible or because I'm trying to hold onto everything while I turn it. > The outer gears appear to want to wobble too. Could just be too tight a > mesh from the 3D printing side of things.
My guess is that the spider is too willowy, see my comments in the previous post to Todd about how to stiffen it up by making it as two rings with a bolthole thru the pillar, in the gap just outside of the pinion teeth. the trick is to keep the pinion shafts dead vertical between the rings by locking the rings together. It could also be that the pinions are out of time with each other, perhaps a printed in marker at the exact both sets of teeth are aligned point to help when inserting the pinions on the shaft, with the marker being used to establish the correct timing? Piece of cake if there are 3 pinions and a 3 tooth diff in the ring gears, they all point east at the same time. But thats not what you have. pinion timing correct would be when its running, zero wobble of either the spider rings OR the output, moving ring when everything is in time. And there is one correct, and n! ways it could be wrong. Make the marks, it couldn't hurt. And with 3 pinions, each with 40 or 41 teeth, n! is well out of range of my elderly SR-51 as it only has a 2 digit exponent. I have a gnawing feeling in the back of my mind that with three pinions, you need a three tooth diff in the ring gear tooth count. But I'm hoping I'm wrong. > Oh and beveling was done by chucking up a piece of casting sprue, turning it > to 20mm and drilling tapping a 1/4-20 hole. Slide on the gear, clamp with > fender washer and bolt. I ran a 30 degree bevel on the compound and then > used a dirty wire brush with the lathe stopped to clean out the bits of > plastic hanging on. > > Previously the gears had all been reamed with one of those expandable > reamers and the spider posts sanded and smoothed to the gears spin freely > without any play. > > John 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
