Bearings?

[hootie]

Has anyone tried to print parts that can be used with sealed bearings? I'm curious of the fit. I'm developing a prototype, and have one part that used two sealed bearings. Something tells me it will be trial and error. Anyone have any thoughts?

[Ama-fessional Molder]

Well. If you are confident that you can get overall dimensions correct, you can start there with a test piece, measure the resulting hole, and then apply your offeset to only the hole dimension before another print.


A trick we use in manufacturing is to chill the insert, in this case your bearing, and insert it into the part while the material is still hot. When the part cools fully and shrinks over the course of an hour or so it will result in a very tight fit. That would mean you want to have the bearing cool and at the ready (stick it in the freezer) and the moment the print finishes and the plastic is all still fairly warm drop it in.

This also gives you a slightly larger margin of error to work with, and since you are dealing with plastic there is even more play. Plastic will shrink to fit around a steel insert without causing too much compression to induce premature wear in the bearing like you find in a steel piece.


You will have to be careful if you are putting the bearing in mid-print, or if you require force to slide it in. This method works best with a drop in, or "slip" fitment while warm, forcing it into a warm part not only can, but will distort it.

If done correctly, you can have an interference fit bearing which does not require additional means to secure it to the part. If you are really slick with the design, you could even build the bearing into the print - just pause it when the walls are complete, drop it in place, and print over the top of it. You will see some challenges with that however, but as with most makers I suspect you can overcome.