Coefficient of thermal expansion...
.. of aluminium is 22 - steel is 13.

If you cool it down the aluminium will shrink at twice the rate of the steel.
( Ugi , it's a game of give and cake, Fri 11 Mar 2011, 14:57, 2 replies)

So...
heating the whole lot up, then rapidly cooling the aluminum components would potentially free them?
(Monchberter Can't go wrong with Doom, Fri 11 Mar 2011, 15:11, closed)

that sounds like a good solution
I suggest using first a blowtorch and then a CO2 fire extinguisher
( Vipros. clever got me this far, then tricky got me in, Fri 11 Mar 2011, 15:17, closed)

*Checks man drawer*
Nope, can't see a blowtorch or CO2 extinguisher, what about heating it on the cooker and plunging it in the sink?
(Monchberter Can't go wrong with Doom, Fri 11 Mar 2011, 15:22, closed)

What's for dinner?
Could work - fill the sink with iced water, heat the whole area and the plunge the aluminium part into the ice.
( Ugi , it's a game of give and cake, Fri 11 Mar 2011, 15:24, closed)

Maybe....
The problem is that as you heat it up the joint will get tighter (the aluminium will expand more than the steel). However, aluminium is very conducting - much more so that steel and so you may be able to free it by then cooling the aluminium part quickly while the steel stays hot.

The other approach is to cool the whole area. When the whole lot cools, the aluminium will shrink more than the steel. Not too sure whether practical methods of cooling it will be enough thou'.


Edit vipros' method of a CO2 extinguisher might do it: -78'C. Wear gloves.
( Ugi , it's a game of give and cake, Fri 11 Mar 2011, 15:21, closed)

Now I have a vision
Of someone trying to wedge a bike into a Chest Freezer. I have often made installing bearing shells easier by putting them into the freezer overnight first.
(Mackeson_drinker, Sat 12 Mar 2011, 7:16, closed)