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Posted by Gerald Miller on April 24, 2008, 7:40 pm
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On Thu, 24 Apr 2008 20:51:11 +0100, "newshound"
>
>>>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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Posted by Ignoramus26128 on April 24, 2008, 7:58 pm
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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 Thu, 24 Apr 2008 20:51:11 +0100, "newshound"
>
>>
>>>>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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to spammers, I and many others block all articles originating
from Google Groups. If you want your postings to be seen by
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posting on Usenet.
http://improve-usenet.org/
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Posted by Gerald Miller on April 24, 2008, 8:18 pm
Please log in for more thread options On Thu, 24 Apr 2008 18:58:15 -0500, Ignoramus26128
>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 was re posting something from several years back, but yes, that
would be how it was done. You can get them up to some impressive RPMs
that way - enough to explode the outer race I'm told.
Gerry :-)}
London, Canada
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Posted by Larry Jaques on April 24, 2008, 11:36 pm
Please log in for more thread options On Thu, 24 Apr 2008 20:18:04 -0400, with neither quill nor qualm,
>On Thu, 24 Apr 2008 18:58:15 -0500, Ignoramus26128
>
>>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 was re posting something from several years back, but yes, that
>would be how it was done. You can get them up to some impressive RPMs
>that way - enough to explode the outer race I'm told.
You forgot to tell them to bend over it while they spin it, Gerry.
<evil grinne>
--
Happiness in marriage is entirely a matter of chance. If the dispositions
of the parties are ever so well known to each other or ever so similar
beforehand, it does not advance their felicity in the least. They always
continue to grow sufficiently unlike afterwards to have their share of
vexation; and it is better to know as little as possible of the defects of
the person with whom you are to pass your life.
-- Jane Austen, Pride and Prejudice, 1811
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Posted by Gerald Miller on April 25, 2008, 12:39 am
Please log in for more thread options On Thu, 24 Apr 2008 20:36:09 -0700, Larry Jaques
>On Thu, 24 Apr 2008 20:18:04 -0400, with neither quill nor qualm,
>
>>On Thu, 24 Apr 2008 18:58:15 -0500, Ignoramus26128
>>
>>>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 was re posting something from several years back, but yes, that
>>would be how it was done. You can get them up to some impressive RPMs
>>that way - enough to explode the outer race I'm told.
>
>You forgot to tell them to bend over it while they spin it, Gerry.
><evil grinne>
All the more reason not to do it
Gerry :-)}
London, Canada
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