On a 3/16" shaft/hole, 400 F will give you an expansion of about .0006".
Not enough to make it worth the hassle of trying to assemble it.

Bob May wrote:
One thing that nobody else has mentioned is to heat the brass flywheel to
maybe 400F or higher before putting it on the shaft. You will want to make
the hole only big enough to just fit on the shaft at that temp and the brass
will shrink considerably when it cools and hold hard. It will also help to
knurl the part of the shaft were the flywheel goes and this can quickly be
done with the edge of a fine file. You don't need to do a real deep knurl
to make it hold well.
When you do the pressing, a jig to hold the rod so that you can drive the
flywheel solidly to the spot where it belings will help. Even just a hole
in a block of wood if you need the flywheel in from the end an inch or so
will do fine, depending upon how accurately you need to have the flywheel in
a particular place.

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Why isn't there an Ozone Hole at the NORTH Pole?