This weekend I tried printing Rayraywashere’s ball bearing with mixed success. The plastic spheres inside we pretty well fused to the sides of the bearing, which made for a difficult cleanup. Although it got better with time, it was a laborious process. Ultimately, printed bearings that rely on printed balls may not be the way to go for everyone. Even if you can print it without fusing the balls to the bearing, there’s no guarantee the balls would be sufficiently spherical to work properly.
That ball bearing design got me thinking – if I could find a reasonably ubiquitous and cheap alternative to small printed spheres, I could make the entire design much smaller and probably significantly more reliable. The photo above is rough draft/proof of concept for a printed bearing only slightly larger than a traditional 608 bearing. Rather than printed spheres, it uses plastic pellets of the sort typically used as stuffing in craft projects. I sorted through a lot of these and used only the most nearly spherical ones. However, there was still a lot of variation that lead to the bearing getting jammed.
Later I emptied the plastic pellets and tried out small spherical 3mm plastic beads. These have worked really well in this printed design. To improve upon this design I intend to move the “bead filling gap” to the interior ring or change the ring system so that two rings will snap together and cover the filling gap. Overall, I am very happy with this result. I’m looking forward to actually installing a slightly smaller version into my Cupcake 3D printer in place of a 608 bearing to see how well it works.
I spent $4.00 for 1700 identical plastic beads, silver in color, 3mm in diameter. It takes about a dozen of these beads to fill the bearing. The potential savings are pretty self-evident. The per-unit cost for each bearing is probably only about $0.05 or so in plastic and beads. That’s pretty good compared to $2+ for commercial bearings. The real test will be how smoothly they work, how well they work at high speed, how quickly they might wear out. However, I think I may be on the right track here.
|Tagged with||ball bearing, bearing, proof of concept||16 comments|