Likely for the 0.5 module setup these would work. https://www.amazon.com/uxcell-6812ZZ-Groove-Bearings-Shielded/dp/B082PQ1NCY/ref=pd_sbs_1/136-5776133-4069347 They have an ID of 60mm which is what I set the 0.5module ring gear OD to. So one could make the ring gear body a bit wider with a raised middle section and slip a bearing onto each side. A lot easier than trying to make a bearing spacer.
> -----Original Message----- > From: Chris Albertson [mailto:albertson.ch...@gmail.com] > Sent: January-03-22 10:53 AM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Harmonic Drive > > Large ring bearings are not crazy-expensive. I was thinking about using > some in a robot leg design. This one could work for your size reduction > drive. Use them in pairs spaced as far apart as possible. They are deep > groove so they can take some axial load. With wide enough spacing you > don't get much play. This company, "uxcell", makes cheap but good enough > bearings and sells on Amazon, eBay and other places like that. > amazon.com/uxcell-6816-2RS-Bearing-80x100x10mm- > <https://www.amazon.com/uxcell-6816-2RS-Bearing-80x100x10mm- > Bearings/dp/B07RQ4RXDR/ref=sr_1_3?crid=21LZ75QCVNKGM&keywords=uxcell+ball+bearing+100mm&qid=1641234560&s=indust > rial&sprefix=uxcell+bal+earing+100mm%2Cindustrial%2C111&sr=1-3> > > I generally press-fit bearing onto the plastic and have to always "post > process" the plastic until the bearing slips on with slight hand pressure. > I have a lathe but I'm lazy and mostly just sandpaper the plastic until > the bearing fits. but if you turn the plastic you get better concentric fit. > > For cheap hardware I now just search for "uxcell" and find screws, nuts > and bearings, precision ground rods and what not, all "decent Chinese > quality". > > Also when you use big ring bearing, threat them as structural member in the > design. A plastic part is very weak but a plastic part with a big > stainless steel ring attached with CA glue is almost as strong as a big > stainless steel ring. > > I discovered "hardware as structure" a few weeks ago as a fix for broken > plastic parts. So I re-printed the part but with long internally thread M3 > or M4 holes all the way through then I fill the hole with CA glue and put > in a long screw. I call it "steel reinforced plastic". Like rebar in > concrete. > > > > On Mon, Jan 3, 2022 at 12:57 AM John Dammeyer <jo...@autoartisans.com> > wrote: > > > For fun I created Todd's version with 0.5module gears. The OD of the > > assembly is now 60mm compared to 150mm. It would now be possible to > > choose a far east harmonic drive tapered roller assembly to hold the driven > > gear in place. Although they are expensive. > > > > Not sure what type of bearings, if any would be used for the planetary > > gear clusters. I suppose one could press in bronze sleeves. I guess it > > all depends on the duty cycle and target application. If it's a 6 axis > > robot arm used for tool changing and placement/removal of milled parts then > > it's not running continuously. Might well for the home or small shop be > > more than adequate. > > > > This example still has 67.3333333:1 reduction but if the fit is well set > > then the backlash is essentially zero which is different from normal > > planetary reduction drives. Not sure how important that is for a 6 axis > > robot arm. > > > > In either case, using a 4th axis to create all three spur gears at the > > same time (one set of 40T and one set of 41 T) and then some sort of > > broaching/indexing to create the two ring gears the real issue is the outer > > bearing of the 101T output ring gear. But overall not that difficult to > > create once you have the 0.5 module shaper style cutter. > > > > John > > > > > > _______________________________________________ > > 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
