Re: ATM 11.2" F/2 Primary testing questions :)

["James W. Burrows" <burrjaw@earthlink.net>]

At 07:15 2001-12-31 -0800, Ric Rokosz wrote:

>The need for such small figuring laps means you should
>leave it in your will for your next lifetime to finish
>it ..:)

I'll second that.  I used HCF "wax dolls" (calculated shapes to reduce 
deviations), much more effective than small tools, on my 10"f/2.6 RC cass 
primary.  According to Everest, you're supposed to go back to a pitch lap 
after polishing with HCF to get an "optical surface"; the trouble is the 
surface got smoother but the figure went to pot.  I'm guessing now that 
pitch starlaps (with calculated shapes) would do the job and leave a 
smoother surface.

Looking at my log (from !long! ago) for the mirror, I started polishing 
with 6 waves of surface P-V.  There had been several grinding sessions 
(some "with 2 in bottom of tumbler & #400 SiC") and flash polish to check 
the figure.  With these fast aspherical surfaces, it's just not possible to 
bring to a full polish then figure.

         -- Jim Burrows
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