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 <[email protected]> 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 > > [email protected] > > 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
