On Wed, 24 Jun 2015 16:55:34 -0700, wrote:

On Wed, 24 Jun 2015 10:32:11 -0400, Ed Huntress
wrote:

On Wed, 24 Jun 2015 07:04:33 -0700 (PDT), rangerssuck
wrote:

In a shop where I worked, a somewhat amusing lunchtime activity was taking clapped-out bearings, washing all the lube & dirt out of them, holding the inner race between thumb & index finger, spinning them up to some insane speed with an air gun & putting them down in the parking lot. They'd go some pretty impressive distances.

We can't let this trick go by without comment. First, if you turn the
bearing to the side while doing that, the gyroscopic effect will
side-load the bearing and likely burn your fingers, unless you
instantly let go, in which case the bearing will run off and hit
something at a very high speed.

If you put your finger through the shaft hole and it side-loads like
that, it may seize and rip off your finger. However, your finger will
have the ride of its life.

Twist off.


Third, if you succeed it getting it to spin up freely, you will,
eventually, learn about the fracture mechanics of hardened 8000-Series
steel, while the outer race explodes in your face.

'Just a caution.
Way back when I was cleaning some wheel bearings from a VW Bug. I was
using air to blow them out after cleaning with solvent. I decided to
spin one up. I put it on my finger and spun it up a little, then a
little more, and then decided to see how fast I could get it to spin.
The pitch of the sound coming from the air accelerated bearing rose
higher and higher. Just when it got high enough that I couldn't hear
it the thing exploded. I thought my finger was broken. Pieces of
bearing stuck into the sheetrock. Learned my lesson that day for sure.

I'll bet. I'd be more leery of the bearing retainer sheetmetal
shredding (cleanly, or not so) taking all the muscles and ligaments
off the finger as it failed.

--
Find out what people will submit to, and you have found out the
exact amount of injustice and wrong which will be imposed on them.
--Frederick Douglass