On 29/11/2019 13:07, Chris Green wrote:
I have a small fan motor that I need to replace, the fan is mounted on
an aluminium (I think) collar which is siezed on the shaft.

So, what's a good approach to getting it unstuck? I've drilled out
most of the grub screw that should be holding it, I doubt that's the
issue now. It's just that the collar is very firmly stuck on the
shaft.

There's lots of "how to get steel studs out of aluminium cylinder
blocks" advice I can find on the web but my problem is the other way
around. Is there anything in particular that might help apart from
all the usual things like soaking in penetrating oil, bashing it,
etc.?
Heat will do it. Also, try knocking the collar down the shaft a short
way (perhaps with a suitable "socket" or box spanner)

It's quite small, the shaft is about 7mm (possibly 1/4") diameter. The
end protrudes only 1cm or so beyond the fan, I can hold it in a vice
quite firmly but the fan is quite flimsy so brute force rotation of
that is rather difficult.