Greetings all; It has come to my attention that one of the potential failures in my harmonic drive with a loose belt experimentation, which seems to be caused by the unequal shrinkage in the xy direction as opposed to the z direction is at least partially caused by the nozzle diameter. If I attempt to achieve a zero clearance bearing simply by shrinking the dummy ball from about .5mm bigger than the bearing, as it shrinks, the wider edges of the bearing groove come into zero or a slight preload condition, leading eventually to a race fatigue split at the center of the races width. Working in openscad, a scale command would fix this by shrinking the bb shape used for clearing that groove, only in the x direction.
Th question is how much would it take to transfer the majority of the stresses on the race from being on the outer edges of the race, to be more concentrated on the center of the race, with an eye toward reducing the splitting force on the bearing race. 1% x shrink, 2%, 3%, what would be the ideal amount of shrink to compensate for the printers .4mm nozzle, being used to only lay .12mm per layer? Seems to me there ought to be a way to mathematically predict how much that shrinkage diff there is. Attached, an extra 2 lines to draw that away from the bearing itself, showing how little the difference is for a .97 x shrink. Comments plz? 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
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