husqORbust
ArboristSite Operative
I reckon chilling the bearing has more to do with the time it takes to expand, rather than how much it shrinks.
Take a .003" heat shrink fit for example.
Chill bearing from 2.0000" to 1.9998"
Bearing is 2.0000" at room temp. Bearing expands to say..... 2.0010" at some temp between room and an expanded bores temp
Bore is 1.9970"
Apply heat to bore, it expands to 2.0010"
Now its a .0010" slip fit.
If it took 2x as long to go from -20°C to expanded temp than it took from room temp, you would have boughten yourself 2x the time to seat your bearing in a very small window of opportunity where there is a .001" slip fit. Knowing that, freeze your bearing, heat the case up, put it together square, and have something to hammer it within a split second if it hangs up.
In the best practices, a piece of dust will damn near hang up a .001" slip fit...so having .5 of a second extra to drop something in the hole is major.
Or, skip the freezing process, and properly heat the case up. In any event, I think if the bore isnt HOT enough, you'll have problems.
Totally arbitrary numbers. Just trying to illustrate my thoughts on what freezing will actually do with a heat shrink fit up.
Take a .003" heat shrink fit for example.
Chill bearing from 2.0000" to 1.9998"
Bearing is 2.0000" at room temp. Bearing expands to say..... 2.0010" at some temp between room and an expanded bores temp
Bore is 1.9970"
Apply heat to bore, it expands to 2.0010"
Now its a .0010" slip fit.
If it took 2x as long to go from -20°C to expanded temp than it took from room temp, you would have boughten yourself 2x the time to seat your bearing in a very small window of opportunity where there is a .001" slip fit. Knowing that, freeze your bearing, heat the case up, put it together square, and have something to hammer it within a split second if it hangs up.
In the best practices, a piece of dust will damn near hang up a .001" slip fit...so having .5 of a second extra to drop something in the hole is major.
Or, skip the freezing process, and properly heat the case up. In any event, I think if the bore isnt HOT enough, you'll have problems.
Totally arbitrary numbers. Just trying to illustrate my thoughts on what freezing will actually do with a heat shrink fit up.