Roller-brearing z-screw experiment (Dollo3D)

thingiverse

This is a fully 3D printable z-screw roller-bearing thingamajig I came up after couple of years tinkering with Dollo3D and trying to get a fully 3D printed Z-axis done. It is quite possible that there's a wee bit of over-engineering in play here, or simply madness, but the idea actually works and I've had this running on my Dollo3D.2 printer for over a year now and after more than 500h of print time, it's still going on strong. I had a looksee inside the contraption few months ago and there isn't even noticeable increase in play between the parts which I find quite supprising. Also the accuracy of the z-axis is supprisingly good. The thing is quite loud, though... So what and why? In the beginning I was going for a simple 3dprinted screw-nut combo, but I started thinking that with plastic parts the screw would wear out unevenly (because we hardly ever use full z-height) so I started thinking about somekind of bearing where the wear doesn't happen on the screw. So after few scrapped ideas I thought about rollers against the screw and after few iterations, here we are. I hope the wear now mostly happens in the rollers/roller axles. The reason why the screw and rollers have a multi-way gearing is to make sure the rollers keep on rolling. With simple screw without the extra teeth, it was possible for the rollers to stop and start wearing out unevenly. Parts to print: - 1 top housing - 1 bottom housing - 3 rollers - 3 roller axles - 6 washers - 3 housing screws - x amount of screw parts - x-1 amount of screw centers Housing assembly should be straightforward. Z-screw assembly in case of multiple screw parts needs glue and the center parts to keep things aligned. The source files are here: https://github.com/spegelius/Dollo, see z_screw.scad For linear rods I use this: https://www.thingiverse.com/thing:2613202 I might do some further development on this someday, like make this kind of a planet gear type where the rollers aren't fixed on the housing.