On Wednesday, December 15, 2021 6:31:21 PM EST John Dammeyer wrote: > I still haven't been able to make a simple circle in FreeCAD. I keep > looking for the Alibre way of doing it which for my brain has always been > close to perfect. Never could use AutoCAD and I find Fusion360 confusing . > However the gear tool is quite nice in FreeCAD. > > I'm still having some problem visualizing exactly how the gears turn to > create 67:1. So I thought I'd blow a bunch of money on filament and print > them. In hindsight I should have expanded the pinion holes to 22mm since > that's a standard (cheap) bearing size. > > Too late now. Just over 2 hours before the other 4 are done. I could make > some tubes that hold smaller diameter ones. Or just play with the motion > here first. See how it works and then decide if I want to use my module > 1.0mm cutters to make them out of metal. > > Or just print ones with inset relief to hold 8x22x7 standard bearings. > John [...] The 4 pinion model intrigues me, so I may. when my printer parts get here, rethink my A axis design. By making the output disk fit directly on the shaft of the axle after superglueing the existing belt pulley to it, or locktite as the case may be. It fits on the axle shaft with a single machined into the bore key, and that key is schloppy, hence the superglue or locktight. Or maybe print the output disk with a bigger key. The schlop as it is, gradually loosens the retainer nut until it has about a degree of backlash. The axle is lower than the motor shaft, in this A drive and putting the drive inline with the motor shaft restricts the max diameter since the gantry bottom should clear it if it gets that far to the rear. That restricts me to about a 90mm OD for the whole thing.
By moving it to the axle shaft, I have about 30mm additional room to play, or 120 mm and will still have 2 or 3mm clearance to the mounting bed. I have a bag of 6.5x17x7mm bearings to use for the pinions. I'll still use BB's for the outer bearing of the output disk. Or if I make the disk thick enough, the axle bearings will suffice. But no openscad work will be done until my printer repairs arrive, and I just got notice from fedex that the expected Friday delivery will be delayed. CZ is a fur piece away from Weston WV. I don't see a way, with these small a bearings for the pinions, that I can do the pinion disk in one piece. its going to have to be a sandwich in order to support the pinions with adequate rigidity. For pinion disk bearings I have a few 7mm wide, 35mm bore, 47mm OD that should stand at least 1000 rpms for the input shaft turning the pinion disk. Question: This little bearing I have a bunch of seems to have a high wear rate. Since the pinions have room for an even bigger bearing than the std skate wheel mentioned above, is there another sweet spot pricewise with a 10 or 12mm bore? With that big a bore, the pinion driver disk could be made with substantial posts, and only one sided and still be rigid enough. Just thinking out loud. 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, 1940) 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
