Bearing temps frustration.

[Canyon Angler]

So I guess the bottom line is, chilling the bearing can't hurt, but might help, especially given the fact that aluminum is super thermally-conductive, and will dump its heat (via conduction) into whatever it touches, as fast as it can, and the larger the Δt, the faster the heat will transfer from the hot part to the cold part.

Now, if you were trying to do the reverse -- fit an aluminum part into a steel hole -- then chilling the aluminum part would make a much larger difference due to aluminum expanding/contracting about twice as much as steel for a given temperature differential.

This reminds me of that old wive's tale about how hot water will supposedly freeze faster than cold water...

 

[sean donato]

You’re going off topic Sean, I agree at liquid nitrogen or dry ice temperatures which are between -80 to -200c of course there will be a useful advantage for even chainsaw bearing instal. No one is questioning that. In fact I’m very aware that even the warmth of your hand holding a piece of metal, that has been machined to fit at room temp (so a change by what, maybe 15c) no longer will fit if you hold it a few minutes.

I’m testing if your home freezer has the ability to make any practical difference in installing bearings into chainsaw pockets (which so many teach and recommend as gospel).

Precision machine / milled / lathed fits where the mating surfaces are perfectly round within microns, any temp change makes a big difference to the fitment, that’s a precision fitment. A 40 year old cast chainsaw bearing pocket is far from precision.

People can do whatever they like and whatever makes them happy though, it was more to clarify it for myself and if others wanted to come along for the journey then all the better. Enjoy the video,

Tom I don't believe I was off topic, my response was to the guy I quoted, whom basically said we're doing it this way because we don't know any better. That's a lie. I did enjoy reading and watching you go about it as scientifically as you could, but will not sit here and debate the practicality of doing it in saw cases. It works. The degree of success is directly proportionate to the temp difference and expansion/ contraction rate of the base metals. Which you've shown very well to be true. I was not and am not attacking your method, nor discrediting that you can't seem to make it work very easily at your home. You found something out informative to you, and will likely venture to a new or different way of installing bearings, and thats OK. Cheers.

 

[Vintage Engine Repairs]

So I guess the bottom line is, chilling the bearing can't hurt,

Hmm yes and no, I don’t think condensation which will come from freezing and then heating will do any good. Nor the time waiting hours for it to freeze. I guess this is why I re tested it, to see if accepting condensation and waiting 12 hours to get it to temp was worth it. Do you freeze your bearings for instal? I’m curious if others will still freeze them.

 

[Canyon Angler]

Do you freeze your bearings for instal? I’m curious if others will still freeze them.

I do ... but not for 12 hours. More like 1 hour, which is about how long it takes for a warm beer (which contains a lot more BTUs than a warm bearing) to freeze solid.

As for condensation, bearings usually have some grease or oil in them (and they will get condensation on them in a barn or garage all the time, anyway). Hell, I have wheel bearings on boat trailers that get dunked in SALT water all the time and still last for years and years, if not forever...and when they do go bad, I suspect it's mostly due to excessive lash, not saltwater...YMMV.

 

[Bob Hedgecutter]

I do ... but not for 12 hours. More like 1 hour, which is about how long it takes for a warm beer (which contains a lot more BTUs than a warm bearing) to freeze solid.

As for condensation, bearings usually have some grease or oil in them (and they will get condensation on them in a barn or garage all the time, anyway). Hell, I have wheel bearings on boat trailers that get dunked in SALT water all the time and still last for years and years, if not forever...and when they do go bad, I suspect it's mostly due to excessive lash, not saltwater...YMMV.

Garage!? Barn!? You heathen! Should they not be shelf stored inside ones abode? Kept in the same heated and or air conditioned conditions as the owner/operator?
What about the air mixed with the fuel you run them on, is there not a moisture content involved with that, when the saw is shut down and cools- what is the crankcase full of?

 

[Canyon Angler]

Garage!? Barn!? You heathen! Should they not be shelf stored inside ones abode? Kept in the same heated and or air conditioned conditions as the owner/operator?
What about the air mixed with the fuel you run them on, is there not a moisture content involved with that, when the saw is shut down and cools- what is the crankcase full of?

Little-known fact: The combustion of hydrocarbons produces dihydrogen monoxide which is the #1 greenhouse gas! (In fact, about 2 gallons for every gallon of gasoline burned.)

 

[bwalker]

I have access to liquid nitrogen. I cool the bearing with it and heat the case with a trip to the oven until 200 degrees.
I've also just pressed them in, but I feel the heat cold thing works better with less risk of cracking or scraping the case surface.

 

[Madmantrapper]

Man you got to be careful with LN2, you drop that bearing it might crack.

 

[bwalker]

Man you got to be careful with LN2, you drop that bearing it might crack.

In industry it is very commonly used.

 

[Madmantrapper]

In industry it is very commonly used.

For shrinking bearing? I've only used it for cooling spacecraft to simulate outer space.

 

[L34]

Freeze bearing overnight.
Heat case (to what temp,FIIK)
Never had a bearing that didn't just drop in.

 

[bwalker]

For shrinking bearing? I've only used it for cooling spacecraft to simulate outer space.

Yes, and that's the sole reason I have access to it.

 

[kybob]

We use a co2 fire extinguisher at work.
Put clean rags in a bucket. Lay the bearing on the rags and bam. Insta freeze. I most often makes the difference between sliding the bearing ( or sleeve ) in vs beating on it.


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[kybob]

We were taught that roughly 1/2 of bearing failures were caused by improper installation. Don’t know if it’s true or not but I do know the more careful you install it the better.


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[bwalker]

We were taught that roughly 1/2 of bearing failures were caused by improper installation. Don’t know if it’s true or not but I do know the more careful you install it the better.


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I have been told the same thing when I went to a pump school years ago.

 

[kybob]

The biggest thing they stressed was not to drive through the rolling elements. Whichever race is held , push or use bearing driver on that race.
And to prove it, we ( as a class ) drove a bearing on a shaft by driving on the outer race. A major no no. Then pulled it off and cut it open. Sure enough, little dimple marks on the races. And you could feel the marks too. The rollers ( or balls ) are harder than the races. I never knew that either. Very good class. Covered internal clearances , fit tolerances, correct lube type and amount.


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[iowagold]

We were taught that roughly 1/2 of bearing failures were caused by improper installation. Don’t know if it’s true or not but I do know the more careful you install it the better.


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same here...
we use a bearing induction heater for the ones that can be heated with out issues...
and on the super tight stuff
that hot cold thing works for us.
hot on the over size and cold on the under.
yea co2 works well or dry ice if you can get it.

 

[iowagold]

The biggest thing they stressed was not to drive through the rolling elements. Whichever race is held , push or use bearing driver on that race.
And to prove it, we ( as a class ) drove a bearing on a shaft by driving on the outer race. A major no no. Then pulled it off and cut it open. Sure enough, little dimple marks on the races. And you could feel the marks too. The rollers ( or balls ) are harder than the races. I never knew that either. Very good class. Covered internal clearances , fit tolerances, correct lube type and amount.


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one of the classes even showed pressing on with the outside as a dimple.
pretty cool!
super small dimple in the roller...
big deal when it is a 6 inch bearing at high load.
a small power plant steam turbine...

 

[Vintage Engine Repairs]

I have access to liquid nitrogen. I cool the bearing with it and heat the case with a trip to the oven until 200 degrees.
I've also just pressed them in, but I feel the heat cold thing works better with less risk of cracking or scraping the case surface.

That’s a great resource.

 

[kybob]

+1 on the induction heater. Just don’t make the mistake of turning it on and leaving to get other parts.
Hint, you can smell it before you get back. Boss was not happy. Especially when it’s a double row spherical roller bearing , taper bore preloaded to that journal. ( printing press cylinder )


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