I have a few questions relating to a multiple layered spinner that uses ball bearings to reduce friction, kind of similar to a fidget spinner. The image below is an example of the multilayered bearing spinner.

Bearing Spinner

My questions are as follows:

  1. Does having multiple layer of bearing rings decrease the overall friction on the outermost ring and allow it to spin for a longer period of time?
  2. Does increasing the number of ball bearings in each ring decrease friction?
  3. Are there any formulas or relation that would allow me to calculate the overall run time of the outermost ring for a given tangential force?

The more you increase the number of balls and tracks increases the friction, what does change is the speed differential btween the any track and its predecessor / successor - but guaranteeing that the middle tracks will share the changes of speed....

If you want a suggestion for a long life spinner : use a spinner that is supported in a magnetic field then it is basically only air friction and, if you put it in a vacuum not even that.

  • Thanks for the answer, Solar Mike. However, if I decrease the number of bearing balls, say 4 placed at diametrically opposite ends, the total friction would be reduced as the contact point is much lesser. But does the lower number of bearing balls affect the spinning motion, say I'm just using 3 balls, placed in a triangular formation. – Vijey Jan 10 at 9:02
  • What do you think will happen to the stability? Will the races start to wobble and then slow down? Why don’t you run some tests and find out - you have already built the first version. – Solar Mike Jan 10 at 9:05

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