Hi Gene, Not sure about why a 4 pinion is any better than 3. Also now, as I research more Youtube videos, which I should have done before I started printing, is whether Todd's model was complete.
https://youtu.be/-VtbSvVxaFA Seems like all the others use a sun gear in the middle driven by the motor. He didn't include one. But then that's why I'm printing this. Because I really don't understand how this is driven. 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. _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
