On Tue, 14 Dec, 2021 at 12:31 AM, John Dammeyer <jo...@autoartisans.com> wrote:
To: 'enhanced machine controller (emc)' Todd, I'm not sure I 'get' how it works with the pinned gears. I built a different kind of flex cup drive based on a paper on what is called an HGD_EWG_Drive https://www.geartechnology.com/issues/1013x/harmonic_drive.pdf Here's a really short video of the version of one I created. I used that earlier 3D print harmonic drive for the base tooth form although this type looks like you can use involute profile or even belt profile as the flex teeth follow a circular rather than elliptical gear. Something to play with now that I have some PETG. https://youtu.be/lb6shTgQ1wY I really need to bring in a bigger stepper to play with this. The surplus unit with about 1A at 36V will stall if I even look at it cross eyed. Here's the original I was playing with along side the new one. http://www.autoartisans.com/harmonicdrive/HarmonicDrive-35.jpg I still don't have the right size bearings but did have these tiny ones I bought 20 years ago at a model aircraft show in the UK. So I created bearings that were 22mm diameter. Big issue there they were really only 21.3mm after printing and that caused all sorts of issues because I forgot that detail. I then printed some oversize, created an arbor for them on the lathe and turned them down to 22mm. Now I get 100% connection and zero backlash. This things spins so smoothly just by placing a finger on the wave cup driver and pushing it around. And you can't hold onto the output. http://www.autoartisans.com/harmonicdrive/HarmonicDrive-29.jpg And here's a diagram of most of the bits and pieces. http://www.autoartisans.com/harmonicdrive/HarmonicDrive-28.jpg The main bearings are utility trailer 1" ID roller bearings. I'm waiting for 6101 and 6103 bearings to arrive. Most of the parts will be made from metal. John Dammeyer What happens to these designs if the teeth are triangles instead of involute, with say 10% of the tips clipped. It seems to me that the needed flex to gain the free space for the tooth to "hop" over the mating tooth would be reduced, prolonging the life even further. The pinned, 4 pinion model also looks interesting. The involute tooth profile used in most of the links shown here would need a more rapid engage/disengage, which results in the overly large eccentricity and clearance gaps seen in the original paper. The smaller pinions in the 4 pinion model shown here would make the involute gear shape more desirable. FWIW, the one I built, the one that's 100% printed from PETG except for the crosman BB's as loose balls for the 3 bearings, has now been running at about 500 revs of its input shaft, for about 60 days now, has not failed other than I ripped the output pulley out of the output disk trying to find a tooth count that resulted in a tight, zero backlash belt to the A axle of my 6040 mill. One more tooth was too tight with the available belt. But the drive itself is still running. Driven by a 1NM 3 phase stepper. Its a 30/1 ratio. Could be made higher, but with additional gear down in the belt to the axle of about 4/1, its a bit slow. OTOH, the ability to drive while something in the chuck is being gnawed on by an eighth inch tool doing 20k certainly opens up lots of possibilities. :o) > -----Original Message----- > From: Todd Zuercher > [mailto:to...@pgrahamdunn.com<mailto:to...@pgrahamdunn.com>] > Sent: December-03-21 8:37 AM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Harmonic Drive > > It was easier to model in Freecad than I expected. I'll try to attach a jpg > of it and see if it goes through. > > And if it doesn't go through a link to it on my Google drive. > https://drive.google.com/file/d/1_eSu-olALMsevTnOpzQ1o1r_rPjfexwU/view?usp=sharing > > Here is a link to the Freecad file (Freecad v0.18). > https://drive.google.com/file/d/1GGwG9nzmYowKeuMAWMvOExeGrvSzZCnY/view?usp=sharing > > > 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<mailto:bodge...@gmail.com>> > Sent: Thursday, December 02, 2021 6:40 PM > To: Enhanced Machine Controller (EMC) > <emc-users@lists.sourceforge.net<mailto:emc-users@lists.sourceforge.net>> > Subject: Re: [Emc-users] Harmonic Drive > > [EXTERNAL EMAIL] Be sure links are safe. > > > On 2 Dec 2021, at 21:14, Todd Zuercher > > <to...@pgrahamdunn.com<mailto:to...@pgrahamdunn.com>> wrote: > > > > What if you used two outer ring gears of the same diameter one with one > > fewer teeth. Then have 4 sets of planetaries stacked in > pairs. Each pair would be pinned together > > You can just use pinions twice as long as the ring gears. I think I have seen > this done > > It would work with all-external gears too. > > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net<mailto: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%7Ce891b8fadd884297a79608d9b5ed4669%7C5758544c573f47cebee9 > 6c3e0806fb43%7C0%7C0%7C637740852975732935%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJ > BTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=16s%2BM61vPdzTAtr3Qg6ttYnRU6%2Fg4vkOsrYcbPRxmuY%3D&reserv > ed=0 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net<mailto: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
