Yep, in this case, quite literally surfaces of revolution!
I'm just about positive that a large telescope mirror was cast on a
spinning platform in recent years. A whole electric furnace was
built to rotate, raw glass was melted, and the platform never stopped
until the glass had slowly cooled, iirc many months later.
I believe they had either a standby generator, or some special
arrangement for uninterrupted power. The platform might have been 30
feet or more in diameter; with things like power transfer (sliprings,
iirc), temperature controls for many 100s of kW, and tight speed
control, it was no casual undertaking. My recollection is that the
project went quite successfully; it's probably documented in some
detail in Sky and Telescope (did it change its name?) magazine.
I've also heard of spinning mercury pools that worked quite well.
Nicholas Bodley |@| Waltham, Mass.
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