I was not suggesting a cycloidal drive for your application. You need something that can't be back driven and harmonic is best. My comment was that soon you will know more than the designer of this thing. I did that with printed drone chassis. I made a bunch then broke them and made more. Plastic works well for prototypes and learning but in the end you can't beat metal for things like gears and bearings.
For my toy car project, I started with printing the ball bearing units as a disk with a hole in it. They work for about 5 minutes. Nest I made them from mild steel and they work well. In the final build, I buy real deep groove bearings. Same with my printed timing belts. They work for hours. Then I deside to change something. When the design a fixed I'll buy real belts, real bearings and make the motor mounts with aluminum. In my case, I need back drivable reduction systems that are ultra compact for robots. I don't need a huge strength because a large impact spins the motor backward and with luck we recover that energy back to the battery. If you design from the start around cheap bearing you can save a pile of cash. 608ZZ type can be bought for 14 cents each from China ebay.com/itm/100PCS-608-ZZ-Skateboard-Bearings-Double-Shielded-8x22x7 <https://www.ebay.com/itm/100PCS-608-ZZ-Skateboard-Bearings-Double-Shielded-8x22x7-Miniature-Ball-Bearings/352974583128?_trkparms=ispr%3D1&hash=item522eecb558:g:AGkAAOSwLDBeSrYr&amdata=enc%3AAQAFAAACcBaobrjLl8XobRIiIML1V4Imu%252Fn%252BzU5L90Z278x5ickkWpEuxXwAiCNKyBQsQ5%252Fe6zm0BtkgVWXrrOO4c6YeFioRXgcfHxC5iQg%252Ft9%252FppmHUcWjsmucH03fvaMfJiBJRRTdZwZ4txyGIPeB3HQaPB7RbAzHvkrRopmv9go53pr07neZRsdSg61wJTgbRc5sYqaWVCBNrb9grvaOsFaWkMpcP7B0UUEMVlLO%252FRp%252BujTzoMz1zj1xhonxq8y05CjhdWjA3bwose717bboi%252F11zgNQbGqJKEQ3Hn5rAFXwjwucrrKd9fRvrU3ZM5fw6zxMWJiTYpQAK33uuRaQFLR%252FDKEDLnaAeVhy3hjdXI646MJByh%252FoDwJvMJFD%252FswNrIeeIraUzIPpXGbQrvXcwP7KQYr4bllK8MOfetjnvAk7IVQZ7qML2Bqmzx81LSgBL3xVRZZsy5UNQxaNOEEHdBn%252BkNMAZbBL%252BBq5UAK%252FuHVjUlHWOa6k6CZLyQ3Gyob6Xh2gKkQHSyKQeYmwY8eGK0GTrCV1p%252B6UPuxUd06r1nCHEKEYeXio9ANulrelmN2Vm2wELv4GV2SOPbvQlISpuyF833FBeITe6Dhub3%252F5YtGLc7HqyO9tXp%252B8wQbE5GhgWCeNf1g0j8XXzaroCWj2%252BWUYtPJ1xbEEz9SK801cl%252FGIVO6KSS%252BC2cm%252FjNK0SAOw0czGMH9%252F8RjTYPj7%252F49yf3BQ5oyqKl0inSI6Etd6%252B1lj7tYHWkEvnkpKTpaHDNCWwztPoiPkJofm5R5x8bh%252FpRJeXmGE%252BA5fYTzDRFqh2avQJ%252Fl2reHdFGk4Rf%252BLom%252FRNXxRN7A%253D%253D%7Ccksum%3A35297458312830445aba5ec142f897fae9853a103a97%7Campid%3APL_CLK%7Cclp%3A2334524> Same for smaller ones https://www.ebay.com/itm/100pcs-623ZZ-Ball-Bearing-3x10x4mm <https://www.ebay.com/itm/100pcs-623ZZ-Ball-Bearing-3x10x4mm-Stainless-Miniature-Bearings-Shielded-Greased/263803498544?epid=25004954353&hash=item3d6be9f030:g:YK4AAOSw10FdryEu> The trick is to find the good deals on bearings and screws FIRST, then do the design. On Wed, Aug 19, 2020 at 4:19 PM Gene Heskett <ghesk...@shentel.net> wrote: > On Wednesday 19 August 2020 17:52:39 Chris Albertson wrote: > > > I suspect that in the end you will need to design your own reduction > > drive from a clean sheet of paper using what you learn from building > > this. I think I'd make the gear teeth larger so that small printing > > errors don't matter. > > > That also reduces the gear ratio. But I don't have that math handy other > than to note I counted splines and decided it was a 30/1, but I am > observing more than that I think. > > I've made the second new flexgear at the same scale is the other, and > according to my measurements to get full mesh, I need a wave bearing of > 74.23mm so since I've lost the scale references for that part, but have > made several bigger, too big in fact, I switched PLA spools for some > white that I can write notes on, and reset the printer for a scale of > 80.00 per mm, a std I can do math from, and its made the cap, with > prelim measurements indicating it will be about 74.10mm so I'm already > pretty close. The carrier I had in it, which is a hair too small, is > 73.51, and a caliper stretching it to fit 100% at the apex's says I need > 74.23. I should be able to assemble and test this one around 21:00. > That 74.23 is a 2 point measurement, but this carrier has 6 bearings, 3 > on each end. With the other 4 touching, 74.10 might be enough. > > I'm trying to conjure up a scheme to mount a good size rotron fan on the > top frame bar to come on and blow down on the plate to speed up the > glass cooling at the end of the job. The cooldown is a significant part > of the production time for smaller parts like the bearing carrier > > > My plan with my plastic printed milling machine parts is to do a > > boot-strap where I use the plastic machine to make metal parts. You > > might have to do that same, use the plastic reduction units to make a > > better one in metal. > > > > I'm wanting to try to make one of there using rubber timing belts as > > gear teeth. There are some belt profiles that mesh with themselves > > Not without a cyclic velocity variation to deal with. One of the secrets > to the splined design is very constant velocity because the "teeth" are > all carrying load as they slide down the mateing side ramps of the saw > tooth spline format. Thats primarily the reason I chose this project. > Cycloid's share that but with all those bearings, bearing costs will eat > your lunch. > > Thanks Chris. > > 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 > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
