[ATM] Mirror workshop

[Francis J. O'Reilly]

Mitch,

Thank you for your input on the issue of pressure on the back of the mirror
when polishing. We all have our own methods of polishing our glass. Does
mine take longer than that of others? probably so, but to paraphrase what
Porter once said, what is a hobby if not to kill some time. The method I
now use was taught to me in 1995 by an old friend who has since left us,
Bob Goff, a professional astronomical optician from Tucson.

I have tried your method of applying pressure on the mirror when polishing
on my first project, a 6" f/8.? that I started in 1970 when I was 12. It
was an unmitigated disaster. I am now able to achieve a very good sphere
when polishing and then when figuring, I can move forward to my objective
(no pun intended) in an efficient manner.

I usually use borosilicate glass (pyrex) in what is considered full
thickness (1:6 thickness to diameter ratio). I am considering using fused
quartz however for my next project.

I am interested in finding out what type projects that you have completed
or are in progress? I'd also like to hear about the methods that you find
helpful.

Best regards,

Francis J. O'Reilly 

I normally put no pressure whatsoever on the back of the glass when I
polish.

If your coarse polishing pits out I believe you're supposed to use as much
pressure as you physically can, ask anyone, I believe they will agree.

Once you get to figuring of course you want to lighten up to the weight of
your hands or so. 

Mitch

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