If this thing works decent enough - I could easily then 'shape' the outside gears. pretty easy...
sam On Wed, Mar 10, 2021 at 2:00 PM Chris Albertson <[email protected]> wrote: > I've done this a few times. PVA is best used if the mold is new. You can > spray in on the mold using an old spray bottle that used to hold kitchen > and bath spray cleaner that is well rinsed out. But after the mold is used > a few times mould release wax alone is OK. The PVA has some tiny film > thickness and a slight irregular surface and can't be polished. Wax on the > other hand can be buffed and made to shine. The part is only as nicely > finished as the mould. Mould seem to get earlier to release with repeated > use. PVA dissolves in water, so you can soak the mould and part to release > it. > > But it just might be that epoxy does not adhere to rubber and no release > agent is needed. We never used a release agent on latex rubber moulds. > > Carbon fibre parts have this high-tech mystique around them but they can be > made with very crude and low-cost methods using just paper cups, > popsicle sticks and c-clamps. > > You can buy one yard of carbon cloth for about $10 and it is a lifetime > supply. Then cut it on bias into 1/8th inch strips and stir the strip until > they become 1/8th inch long unwoven fibers, (or for more money buy "chopped > carbon fiber") mix with epoxy to make a fibrous paste and this mix is so > strong when it sets you can not break it with a hammer and as lightweight > as foam. > > Now that we have 3D printers we can print moulds and fill the mould with > this DIY epoxy/carbon paste and in effect print strong-as-steel parts. > > I woud cast the ring gear directly inside the aluminum housing so the epoxy > would bond to the aluminum. No need to use screws. The fit would be > perfect > > On Wed, Mar 10, 2021 at 10:58 AM dave engvall <[email protected]> > wrote: > > > PVA seems to be the release agent of choice for epoxy. However, IIUC it > > has limited shelf life. Silicone oils will work but they tend to migrate > > to places you > > don't want them. > > > > Dave > > > > On 3/10/21 9:31 AM, Chris Albertson wrote: > > > This is the best and most durable DIY drive I've seen. One > > > improvement for the future is to make the internal tooth gears from > > > something other than 3D printed plastic. Perhaps you can cast them in > > > epoxy and fiber composite. If you used a timing belt as part of the > > mold > > > the cast teeth would be as perfect as the belt. > > > > > > I can imagine the mold is the square aluminum part with roughened up > > > internal pocket. Then stretch a belt over a disk and place the disk in > > the > > > pocket leaving a ring then pour in the epoxy. With luck the epoxy > bonds > > > with the aluminum but not with the rubber belt. Perhaps the belt is > > > coated in mould release wax. > > > > > > On Wed, Mar 10, 2021 at 7:58 AM Sam Sokolik <[email protected]> > wrote: > > > > > >> another update - at 1/2 step - the discrete resolution should be about > > >> 40,000 divisions per rotation. .009 deg. > > >> > > >> https://www.youtube.com/watch?v=IdfKre6zpEY > > >> > > >> On Thu, Feb 4, 2021 at 4:00 PM Sam Sokolik <[email protected]> > wrote: > > >> > > >>> https://www.youtube.com/watch?v=ZVVffljc7kE > > >>> > > >>> On Tue, Feb 2, 2021 at 9:46 AM Gene Heskett <[email protected]> > > >> wrote: > > >>>> On Tuesday 02 February 2021 08:30:56 Sam Sokolik wrote: > > >>>> > > >>>>> I have looked at cycloidal drives and feel that they have too many > > >>>>> parts :) > > >>>>> > > >>>>> Gene > > >>>>> https://www.youtube.com/watch?v=Gx263nnTrqY > > >>>>> > > >>>>> Ran for over 6 hours like that - about 850rpm input. > > >>>>> > > >>>> I am highly impressed. > > >>>> > > >>>> Now finish the housing, and hang a load on it, like the worm of a > BS-1 > > >>>> while making another worm to replace the crappy worm in the Chinese > > >>>> BS-1. That worm is doomed to a higher wear rate, a fact I'm becoming > > >>>> aware of as I exercise this BS-1 servo for tuning. > > >>>> > > >>>> That is why I bought the ender3, but I was using O.P's code which > was > > >>>> crappy code IMO. Turns out the ender3 can make stuff a heck of a lot > > >>>> better that the code I could DL from thingiverse. I now have the > > >>>> extruder motor on the x carriage, moving a modified stock hot end, > and > > >>>> while its slower than some because the heating is only once the > > filament > > >>>> is in the nozzle, dozens of times more dependable than the stock > > setup. > > >>>> No clogging from cold filament because the hot stuff backs up into > the > > >>>> heat sink and freezes. > > >>>> > > >>>> I think this loose ring idea has the most promise of making a long > > >>>> lasting drive, and shorter axially than any design so far. Please > > >>>> continue. > > >>>> > > >>>> Thank you Sam S. > > >>>> > > >>>>> On Thu, Jan 28, 2021 at 3:13 AM andrew beck < > > [email protected] > > >>>>> wrote: > > >>>>>> Guys just to chime in here. > > >>>>>> > > >>>>>> Sam went don't you design a cycloidal drive instead. They are > easy > > >>>>>> to make on a normal 3 axis Cnc mill with a end mill and much more > > >>>>>> rigid than a harmonic drive. As they are not so fragile. I'm > > >>>>>> planning on making some on my VMC soon. I don't understand why > > >>>>>> use a harmonic drive. (I actually have a big harmonic drive here > > >>>>>> from a robot. ) > > >>>>>> > > >>>>>> On Thu, 28 Jan 2021, 18:53 Bari, <[email protected]> wrote: > > >>>>>>> On 1/27/21 10:55 AM, Sam Sokolik wrote: > > >>>>>>>> Nice being able to make things while I sleep.. > > >>>>>>>> > > >>>>>>>> 2 outside side rings - one 202 teeth - one 200 teeth. > > >>>>>>>> Inside flex ring - 200 teeth. Feels good - for what it is.. > > >>>>>>>> > > >>>>>>>> > > >> http://electronicsam.com/images/greenmachine/IMG_20210127_104237 > > >>>>>>>> .jpg > > >>>>>>>> > > >> http://electronicsam.com/images/greenmachine/IMG_20210127_104628 > > >>>>>>>> .jpg > > >>>>>>>> > > >> http://electronicsam.com/images/greenmachine/IMG_20210127_104354 > > >>>>>>>> .jpg > > >>>>>>> Timing belts will take the flex > > >>>>>>> > > >>>>>>> https://www.youtube.com/watch?v=Y8ZELQdgBbU > > >>>>>>> > > >>>>>>> https://www.youtube.com/watch?v=2YC-0C8oPUo > > >>>>>>> > > >>>>>>> > > >>>>>>> Cycloid prototype under microscope > > >>>>>>> > > >>>>>>> https://www.youtube.com/watch?v=um5GMOBgz6s > > >>>>>>> > > >>>>>>> > > >>>>>>> Hybrid planetary/harmonic drive - check out how they made it flex > > >>>>>>> > > >>>>>>> https://www.youtube.com/watch?v=sdRGrTHq4hA > > >>>>>>> > > >>>>>>> > > >>>>>>> > > >>>>>>> _______________________________________________ > > >>>>>>> Emc-users mailing list > > >>>>>>> [email protected] > > >>>>>>> https://lists.sourceforge.net/lists/listinfo/emc-users > > >>>>>> _______________________________________________ > > >>>>>> Emc-users mailing list > > >>>>>> [email protected] > > >>>>>> https://lists.sourceforge.net/lists/listinfo/emc-users > > >>>>> _______________________________________________ > > >>>>> 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 > > >>>> > > >> _______________________________________________ > > >> Emc-users mailing list > > >> [email protected] > > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > >> > > > > > > > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
