On Monday 24 August 2020 06:15:16 andy pugh wrote: > On Mon, 24 Aug 2020 at 10:35, Gene Heskett <ghesk...@shentel.net> wrote: > > I hadn't thought of that, changing filament is a pita, but worth the > > experiment. > > I think that I would be looking to change the design. Where is it > breaking? > Most of the time right at the junction of the fillet at the edge of the bottom disk, so the separation is at the first layer of wall. However, if the bearings size is adjusted so the splines are fully engaged, then the breakage seems to correspond to the root of the spline.
Best lifetime before breakage corresponds to what I would call about 90% engagement at the maximum, and a hop clearance at maximum pullin between the bearings that doesn't result in a click as they hop over each other. Half the tooth height for clearance is still too much flex, and will break it in under 30 minutes if left running at 4 or 5 rpm at the output. Definitely needs a filament with more elasticity than PLA. What TPU I've seen on you-tube is way too much though. Cura's original wall count was 2, but that breaks by the time the motor has turned 2 full turns. At 6, its better but is beginning to effect the motors ability to turn it at about an amp a coil drive. The TB6560 doesn't map its coils well for microstepping which results in its running at a fractionally slower rpm unless I stop it and restart it from the function generators dials, effectively bringing it up from zero speed. But thats this crappy drivers fault. Thats why you can buy this POS for about $6/copy on fleabay. What we need is a 2M542 for about 2 amps. Yep, a better design and some more flexible plastic is needed. Like Yogi Berra said, is so true. This one needs a bigger pair of main bearings too. That said I found I was gonna be late writing a check for the Missus's keep, so I started a flexgear and got in the truck to go do that. Bout an 85 or 86 mile round trip. On arrival back here it had a clogged nozzle, so I killed that, cleaned the nozzle and rethreaded it, getting some flow at 180C. So that might be a minimum temp sometime. Resliced it, taking a few more defaults, getting the build time down to 10 something hours and restarted another flexgear. This keeps me out of the bars. You can get stuff in a bar, that they don't have a pill for. > If you look at some other designs they incorporate flex-beams. > https://www.thingiverse.com/thing:2951164 > (Not the same type of harmonic drive, it uses two internal gears with > the same diameter but different tooth counts) > I think that the way to make the one you have more robust will be to > make the strain gear more flexible (lower wall count, lower infil, > probably the reverse of what you have been doing) 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
