On Friday, 2 September 2016 16:53:37 UTC+1, Rob Graham wrote:
I posted a mail some 4 weeks ago about freeing up a garden shredder which had seized through lack of maintenance - mine!!

Pressure from the head gardener(!) plus seeing how much a new one would cost has encouraged the DIY approach with heat and brute force enabling removal of the end plate. This allowed access to the grinder wheel and the bolts to take the epicyclic gearbox off the motor.

Because the grinder wheel goes so slowly, just plain steel bushes carry its shaft in the aluminium housing and end plate. These bushes are now running freely, but the end plate one came out with the shaft, so will have to go back into the end plate first.

I guess this will be an interference fit needing heat / freeze.

The question is just how much - I can't do more than -20C for the steel bush, but how much heat will the aluminium end plate casting take?

Thanks for any help.

Aluminium expands lots. You probably won't need much heat.
I remember removing the bushes in an aluminium motor cycle gearbox by putting it in the (gas) oven.