#### brewdexta

##### Forum Supporter

- Messages
- 4,088

Seeing as I'm bored on the train, I thought I would work out theoretically how much the bearing would shrink and the axle expand.

Coefficient of expansion of standard oilite is 12 x10 -6 per degree Fahrenheit which is about 22 x 10 -6 in centigrade/Celsius

Steel is about 13 x 10 -6 per degree centigrade

Assuming a hole/bush size of 52mm

ambient temp of 15c in the workshop

freezer temp of -22

assume I can warm up the big lump of an axle to say 100c with a blow lamp inn the area that matters

equation - linear expansion = coefficient of expansion x initial length x (final temp - initial temp)

results

bush will shrink 42 x 10 -6m and the axle (or the bit around the hole) will expand 57 x10 -6m so in total the difference will be about 0.0001m or 0.1mm which sounds about right.

I should be able to get the axle hotter than that so may get a bit more.

Anyone agree/disagree? Not sure its that scientific as the bush is not solid, may have to work out the circumference of the bush and apply the equation to that an work out how that affects the diameter?

A teabreak conundrum.

Cheers

Andy