[ATM] Initial large thin mirror grinding question

[Ralph <wolfteacher@gmail.com>]

Hello all,
I am lucky to have a library that has a rather complete book on how to
grind telescope mirrors. It's called Standard Handbook for telescope
Making by N.E.Howard. He is very thorough on the procedures involved.
Since this is my first attempt at grinding a mirror, I'm just trying
to get the big picture down as to how all this works.

I will be attempting to grind a 16.5" mirror out of a 3/4" porthole at
some point in the future - probably as a second project.

In Howards book, he describes the initial grinding with the tool on
the bottom and the mirror on top. The book was copyright 1959 so
probably not up to date in all recent developments. But still an
excellent foundation for proceedure. I imagine doing anything with the
mirror on top would be risky as the mirror would flex and bend during
initial grinding process.

Are thin mirror ground MOT first? Or are they ground on the bottom to
have maximum support? Would it be be beneficial to grind a large thin
mirror on an 18 point support system similar to a mirror cell?

Can anyone recommend a thorough complete text on gringing large thin
mirrors other then Mel Bartell's site?

Thanks,
Ralph
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