Sideways Open Bearings

[routercnc]

Hi Tenson

I've answered previous posts on sideways mounted open bearings by pointing out that they will open up a bit with load in that direction. This time however I decided to carry out some stress analysis on a simplified part. The results were quite interesting.

For a 16mm open bearing:

1N load was applied vertically to inner bearing whilst restraining the outer face (the area you would clamp your gantry to).
Displacement is 1.85e-5 mm, therefore 1.85e-5 mm/N.
So for a 30kg gantry spread over 4 bearings thats 73 N per bearing, which is about 0.00136 mm or 1.36 microns.

Initially that seemed pretty small so either there was an error in the calcs or I was worrying over nothing - but then realised that I should really model the supported rail and include that since I think it would be quite significant. Will have to wait for another night . . .

Here are the pretty pictures for the open bearing under 1N vertical load. Stress on the left in N/m2 and deflection on the right in mm.





The FEA discussion ensuing from this post is here: http://www.mycncuk.com/forums/genera...-software.html