Print-in-place eccentric cycloid planetary gear

prusaprinters

<p>This is an example of an idea I've had floating in my mind for a few weeks now, having seen people make eccentric cycloid gears for robot joints on youtube. &nbsp;I thought they might make quite effective printed bearings, because they only (*in theory*) have rolling contacts, and no sliding ones.</p><p>This one needs printing at 50% size otherwise the clearance between the parts is mahoosive.</p><p>When it comes off the build plate it feels like it's locked up and won't turn. &nbsp;It's fibbing to you. &nbsp;Get some grease onto the pins and rattle it around a bit and it'll loosen up. &nbsp;I'm not quite sure what the problem is with the initial configuration: it's not a problem with the print, all the parts are separated cleanly off the print-bed, it's something geometrical.</p><p>This one doesn't spin too cleanly. If you print the top or bottom half alone, when you turn it the pins want to pop out. &nbsp;That's why this one is herringbone-configuration. &nbsp;I <i>think</i> what's going on to make it not spin well is that at the joint between the top and bottom half, the profile is sensitive to being even slightly out of alignment. &nbsp;The reverse in direction of the spiral means that if the planet is even slightly out of position, the profile doesn't fit well. &nbsp;This has 0.4mm clearance between the surfaces by design, which doubles up to 0.8mm if the planet is in direct contact with the opposing surface on the far side. &nbsp;With a 5mm profile diameter (as here) that's significant.</p><p>The next experiment is to see if reducing the clearance makes things better or worse. &nbsp;I suspect introducing a gap in the profile between the top and bottom halves will help too, but that's&nbsp;</p>