Theo, Alec, everybody,
I had access to full workshop facillities, but I managed it with a small gas ring on the stove. The trick is:- Put your flywheel in the freezer compartment (suitably wrapped up so that it doesn't stick to anything!) for a few hours before so that it contracts. Then you dont have to overheat the ring to get it on.
Regards
Dawpooldad.
Wirral