Igus makes plastic harmonic drives: https://www.igus.de/product/20413
> On 26. Jan 2021, at 21:59, Chris Albertson <albertson.ch...@gmail.com> wrote: > > I just did t quick Google and found several companies who make belts > "sliced to order" in any width. 6" wide if you like > > The other way to "print" a flex cup is the print a female mold and fill the > mold with urethane and kevlar fiber. > > I'm working on a robotic/prosthetic hand that uses this technique, Many of > the parts are made with a very strong kind of urethane. This stuff really > takes a beating. This is really a good way to use a 3D printer, You can > make multi-part molds that come apart to allow the molded parts to be > removed. > > > > > > >> On Tue, Jan 26, 2021 at 12:13 PM Todd Zuercher <to...@pgrahamdunn.com> >> wrote: >> >> For the belt idea, it might work better to invert the whole thing, So you >> have the belt teeth in and one gear with two fewer teeth than the belt, >> then the follower wheels on the outside of the belt compressing it to mesh >> with the smaller gear. The hardest part might be finding a belt wide >> enough to reliably flex between the two gear diameters. (Something tells >> me this sounds better than it can actually work in practice.) >> >> Todd Zuercher >> P. Graham Dunn Inc. >> 630 Henry Street >> Dalton, Ohio 44618 >> Phone: (330)828-2105ext. 2031 >> >> -----Original Message----- >> From: Sam Sokolik <samco...@gmail.com> >> Sent: Tuesday, January 26, 2021 2:41 PM >> To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> >> Subject: Re: [Emc-users] Maybe a minimally printed harmonic drive? >> >> plus - you fold one inside out - the pitch doesn't match up very well. >> >> >>> On Tue, Jan 26, 2021 at 1:30 PM Gene Heskett <ghesk...@shentel.net> wrote: >>> >>>> On Tuesday 26 January 2021 13:04:11 Chris Albertson wrote: >>> >>>> The weak link on all 3D printed harmonic drives is the flex cup. The >>>> plastic fails after some hours of use. The best design I've seen to >>>> overcome this is to NOT print the flex cup. They used a wide double >>>> side timing belt for the inner teeth. >>>> >>>> The thing that very few You tubers do when designing 3D printed >>>> machines is to not simply copy the design of metal parts but start >>>> the design from the ground up knowing they will be using plastic. >>>> Plastic has very different strength and stiffness to volume ratios. >>>> So if your part looks like the metal equivalent it is a good clue >>>> you are doing "eyeball engineering" and your experience with metal >>>> is influencing your design. >>>> >>>> If you need to print a reduction gear and need a really big ratio >>>> the Cycloidic reduction system really does work better especially if >>>> the rolling parts are sealed bearing units that are press-fit into >>>> the plastic. >>>> >>>> That said, I've printed parts in plastic to directly replace metal >>>> or even rubber and I just have to accept the very short lifetime and >>>> low strength. Plastic is a good material to verify ideas quickly. >>>> >>>> In any case, use a timing belt for the flex wall and it might last >>>> 30 years. >>>> >>> But that brings up the tooth profile problem. I've not seen a timing >>> belt that resembles the triangular splines? >>> >>>> On Mon, Jan 25, 2021 at 8:47 PM Sam Sokolik <samco...@gmail.com> >> wrote: >>>>> I am sure the torque is limited - but I feel it might have >>>>> possibility... >>>>> >>>>> https://www.youtube.com/watch?v=QlpkmEEhFqc >>>>> >>>>> _______________________________________________ >>>>> 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) >>> 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 >> >> >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > 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
