Can you help me visualize what you were doing? You held the bearing by
the inner race, applied air kind of sideways, and then let go of the
bearing?
i
On 2008-04-24, Gerald Miller wrote:
On Thu, 24 Apr 2008 20:51:11 +0100, "newshound"
wrote:
I've heard that many times, what is the reasoning?
If you spin it too fast and the outer land and cage can come off the
balls, it can take fingers off. I still blow 'em off, but I don't spin
'em much any more.
This may be true; the other reason is that the fatigue life of rolling
element bearing is quite sensitive to surface damage and with a completely
unlubricated bearing spun fast this may occur; certainly if there is any
grit around when it is spinning that will be enough to create fatigue
initiation sites. Of course most ball bearings fail for other reasons than
fatigue.
To re post an item from several years back:
One of the motorcycle race engines I used to race required main
bearing changes after every race. As a result, I had a large surplus
of slightly worn, approx. 1" diameter bearings. A fairly long road
used to dead end onto another road that went in front of our house.
Our driveway was on the other side of the road. I used to spin these
bearings up with 175 psi air and release them to run down the road.
The bearings would EASILY outrun cars driving at ordinary residential
street speeds, spraying sparks all the while. When it hit a gravel or
other debris, it would jump high into the air. Which resulted in some
funny instances. Like when it chose to leap while under a car. Or
when it hops up in front of a car. Driver reaction was interesting.
I learned several things from this experience:
* This is a lot of fun.
* It is fairly hard to turn the bearing while is spinning due to
gyroscopic effect. Turning the bearing can make it seize from the
high side loading.
* When the bearing seizes up while you're holding it, the
friction heat makes a nasty burn on your fingers.
Gerry :-)}
London, Canada
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