I haven't been following your project recently but am intrigued by "And it turns the armature easy enough the 3NM 3 phase motor (those are magic folks, running 50C cooler than 2 phase stuff) I'll use will not be a bit overstressed." Where did you end up getting your motors and what are you using for drivers?
-----Original Message----- From: Gene Heskett <ghesk...@shentel.net> Sent: April 30, 2021 10:45 PM To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Maybe a minimally printed harmonic drive? On Monday 22 March 2021 09:19:19 Sam Sokolik wrote: > 202,200 for the outside spline and the flex gear is 200. In this > situation - the 202 tooth spline is stationary to the stepper. The > 200 tooth outside spline is mounted to the faceplate. In this layout > - the ratio apears to be 101:1 > > In this situation the stepper motor and the face plate spin the same > direction. > > With the same set of outside spines swapped - the ratio is 100:1 > > I am sure Andy can explain it. It doesn't make sense to me. > > Happy with runout... https://www.youtube.com/watch?v=eLyP2YwdstQ > > sam I am running some behind you Sam, with my project, having printer problems kills time and money. Finally settled on an ender 5 Plus, which is working passably well but I've wasted $3k getting there. Any way, I changed the design some from yours, to a 30/1 because those big spines print better, and by making my own bearings in openscad, useing crosman bb's for balls. I put a huge one with over 150 loose bb's directly on the outside of the moving spline, with only the lip of the output coupling disc (printed of course) interposed. And the floating spline has 3 more of those, sized for a good friction fit inside that spline, with both the spline and the bearings made as thin as practical to improve the flex life, and I just took the eliptical armature off the build plate and wiggled in into those 3 bearings inside the loose spline, so thats the driver armature, no commercial ball bearings anyplace like yours. I've made the 8mm hole in the plastic for the motor shaft into a prominent D-flat, and used a cbn wheel to make the flat much wider on the motor shaft, and this armature will be driven onto the motor shaft without any grub screws at all. No clue how long it will run before it bores that hole out and I have to make an alu inner for it. :( But I just now assembled it without the motor, turning the armature by hand, and it works, with no detectable backlash. And it turns the armature easy enough the 3NM 3 phase motor (those are magic folks, running 50C cooler than 2 phase stuff) I'll use will not be a bit overstressed. Those bb's will pound the plastic smooth and get smoother with use. So now its time to finish the output shaft, and make the rest of the housing. Which will be supported by the big bearing at the spline end, and 4 of the printed bearings at the load end. I've got the motor end gnawed out of some 1" stock I had, and I bought a foot of 3.125" thick by 6" wide stuff so I can make 2 output housings. That showed me the current price for extruded alu, scary. I also bought enough rod to make about 4 output shafts, over $200. And I've a spare 4" chuck from a TLM upgrade to a 5" to use on it. Or better yet, buy another 5" from LMS. So I'll get there, if I don't fall over first. At my age, thats always a possibility. I'll try to get some pix of what I've got so far, put up on my web page over the weekend. Along with some of the openscad source files. As usual, this stuff keeps me alone, safe, and out of the bars. :-) 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
