Fidget Spinner Speed and How to Make Yours Spin Longer

Using Camera to measure spin speed - at 1/200s exposure = 17.78 rotations per second

I finally succumbed to the inner child, curious about the fidget spinner, and bought two different models at a St Ives market stall, one for a £1 and the other for £3 (allegedly better quality and being "Sold for 13 quid in Cambridge, metal bearings, will run for several minutes". One's pretty and the other's shiny. Both spin smoothly and the £3 on does run for almost 4 minutes. After the novelty wore off, curiosity set in.

How fast can I spin my spinner?

To measure how fast I could spin my spinner, I picked up my SLR camera. You can set many cameras to take pictures at a fixed shutter speed. I set my spinners running on the table and played around photographing them at anything from 1/500 s to 1/10 s. At 1/100 s I could see a motion blur from the shiny parts of the spinner on my photos, taken immediately after setting the fidget spinning. Initially, this the motion blur was about 1/6 of a circle. 

Therefore in 1 second, the spinner would spin 100 x 1/6 revolutions

This equals (100/6) revolutions per second

which is 16.67 rps or about 1000 revs per minute!

Playing with both spinners at the same table, the speeds they could reach were very similar. I had to glue white spots onto the £1 spinner to measure this accurately.

This was interesting. Both spinners were accelerated to the same speed but the £1 stopped after about one minute, whilst the £3 spin for about 3 minutes.

I moved to the kitchen and set up the camera to 

1. Get the best strike of the spinner for maximum speed. This turned out to be: hold spinner centre with one hand to table and sharply strike a glancing blow on a spinner projection with a forefinger, the swing coming from the arm.
2. Measure the decay speed of the two spinners over time.

From the above graph you can see that I could now reach initial speeds on both spinners of 24 rps, or 1,440 rpm. The £1 spinner (1 in the chart) would now spin up to just under 2 minutes from this starting speed. The £3 spinner (2 in the chart) could spin for nearly 4 minutes. The spinners would lose  just over half their speed in the first quarter of their run time (down to 10rps), then halve that speed again to about 5 rps by half their run time and then coast to a stop. Their decaying speed approximated the shapes of inverse square curve.

Increasing run time

My maximum speeds and run times were pretty consistent for each spinner. I wondered how else I could get them to spin longer. I could not do much about the bearing friction. Perhaps I could change the effect of braking by the air?

I tried placing a transparent round tub over a spinning fidget. The reasoning being, the fidget would start the air in the tub spinning with it. This would reduce the drag. Repeated experiments showed that on average, I could extend the run time of the £1 fidget by up to 20 seconds and that of the £3 fidget to 30 seconds or longer. The video below shows a typical result of the same spinner out in the open on the table and under a plastic tub. The unexpected benefit of the video are the different visual patterns created as the spinners slow down, in relation to the video shutter, working at 60 frames per second.

There was some BrexiTrump news today. In Boston, a planned far right demonstration was swamped by a largely peaceful counter demonstration. All 17 members of White House arts panel resigned in protest after his reaction to Charlottesville, issuing a dramatically scathing letter reproduced here https://www.scribd.com/document/356620864/Members-of-the-President-s-Commission-on-Arts-Humanities-resignation-letter-to-President-Trump. The President and First Lady would also be the first for a long time to miss the prestigious Kennedy Center Honors evening.