[tooseevee]

When installing bearings in cases does it really help to heat the case?

I can see figidizing (yeah, I made it up [/img]) the bearing, but why would a hole in the case get bigger when heated if the whole case is expanding? Would not the case (hole) expand also toward the center of the hole?

PS: I HAVE done this, but I'll bet I could have just frozen the bearings?
PPS: What prompted this is that I enjoy watching total, meticulous, even ridiculously over-the-top restorations on YooToob once in a while.

[AzCal Retred]

The whole case gets bigger, taking the hole along with it. I freeze the bearings also(if some is good, more is better, right?), but I've lived mostly in dry places. Lots of condensation on a frozen bearing at 80% humidity, not so much at 4%.    After the bearing is seated, a little more heat & WD40 have always seemed to make things acceptably dry again.

IF a guy had an inside mike, a non-contact thermometer & propane torch it would make an interesting YouTube Vid to track hole size as you heat the case, hint hint...   Always good to prove what you think you know in my experience.

[tooseevee]

The whole case gets bigger, taking the hole along with it. I freeze the bearings also(if some is good, more is better, right?), but I've lived mostly in dry places. Lots of condensation on a frozen bearing at 80% humidity, not so much at 4%.    After the bearing is seated, a little more heat & WD40 have always seemed to make things acceptably dry again.

IF a guy had an inside mike, a non-contact thermometer & propane torch it would make an interesting YouTube Vid to track hole size as you heat the case, hint hint...   Always good to prove what you think you know in my experience.

     So the whole case half expands from the centers of the holes OUT?

      Sort of like the whole universe is expanding outward from wherever you happen to be located; think surface of an expanding balloon. Every point on the balloon is moving away from every other point?

     Do the thin parts & the thi(n)k parts of the case half expand at different rates?

      Do you really have to answer this? No. I have nothing to prove anything on. Except can I get back up the stairs one more time

[Paul W]

I first heard this question many years ago . My engineering college lecturer (fifty years since I was there) answered it with another question. He said "What do you think would happen if the hole wasn't there?"

[Leofric]

I first heard this question many years ago . My engineering college lecturer (fifty years since I was there) answered it with another question. He said "What do you think would happen if the hole wasn't there?"

Did you ever get an answer to that ?

[AzCal Retred]

The heated area expands outward slightly, "bubbling up" under expansion. Heat a piece of sheet metal to see this effect amplified in thin material. Heating the case effectively "opens up" the bearing hole ID a few ten thousandths. Freezing the bearing makes it's OD smaller. Doing both minimizes total required case heating. Mechanics have been doing this for over a hundred years.

If you had enough measurement tools and a temperature controlled lab you could get good numbers on the total thermal distortion introduced into the casting from heating effects. Or you could just use the effect to your advantage when installing a bearing.

[Paul W]

Did you ever get an answer to that ?

My apology - I thought it was obvious. The hole expands as if the original metal was still in place.