From: "Jerry" 
To: "'Jerry B. Hillman'" , "ATM
List" 
Reply-To: "Jerry" 


I don't know what your knife edge readings are but your shape is not too
bad there. You need to start being real careful not to mess up what you
have. Take some zone readings on that thing so you (and the rest of us)
know how much correction you have.
        It looks like you may be close and just a bit of work in the middle
might turn that into a good parabola. I would use accented pressure but I
will leave it to others to tell you what to do. Accented pressure usually
doesn't work well until you have practiced it a bit.
        You may want to wait until later at night for cooler temperatures to
do your figuring if that is posible. I think you had said it was something
like 90 degrees where you were working. That is hot for the lap... let
alone for you pushing a lap around.
        The temperature is higher than what I have ever tried to figure at
and I just wouldn't really know what anything I would suggest for any shape
you could have would really do at a high temperature. But in general
whatever the pitch lap does it will do faster hot. Not necessarily the same
thing it would do at a cooler temperature though.
        The main thing though is that if quantity of correction is good on
the outer part it would not take much to make that into a nice shape too.

Measure.


-----Original Message-----
From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net] On Behalf Of Jerry B.
Hillman
Sent: Monday, May 12, 2003 8:51 PM
To: atm{at}shore.net
Subject: ATM failed pitch lap


Hi all,
So it didn't work.  The pitch lap mold is great for 12" and smaller
but is hard for larger mirrors.  In redoing it I discovered that the
portland cement between the tiles was coming up with the pitch.  So, a
brand new can of pitch ruined.
I guess it is back to TOT with the 10" sub diameter tool. Clear skies, Jerry

BTW - my web site is back up.
http://www.convertabarn.com/Figuring_2.htm

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