Re: [ATM] Support for slumped mirror

["Polk, Tom" <TPolk@decatur-al.gov>]

Arjan,

I have only worked with "normal" 1:6 ratio blanks. The various
information that I have read on fine grinding and polishing a blank with
a thickness to diameter ratio of 1:17 (and greater) are not in harmony
with one another. Which is OK, since there is more than one way to skin
a cat and what works for one may not be the best way for another.

At the present time, I am waiting on 9 micron from Got Grit to recover
from a failed attempt to "flash" polish with felt pads. An improper
stroke also contributed to the failure. The corrective action:
Go back to 9 micron, pour a pitch lap with Gugolz #64, use a 1/3 COC
stroke alternate TOT, MOT.

The concern I have now is the weight of the glass and the heat from my
hands while polishing MOT introducing astigmatism. Since I have a 12.5"
x 0.75" blank lying around, I would like to use it if the technique
would be beneficial.

Thanks for the reply. What stroke did you use on your 10" f/6? Did you
alternate TOT and MOT? How did it turn out?

Tom Polk


-----Original Message-----
Arjan te Marvelde

*SNIP*

Why do you need backing for this mirror? It is not that thin.
A 10"-f6-same thickness, gave no noticeable heat or pressure induced
effects. If you randomize your moves, use a plaster tool and touch the
glass
mainly at the center it should turn out OK.
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