Re: [ATM] fishing for a lil polishing advice!

[Jim Burrows <burrjaw@earthlink.net>]

At 2007-05-21 14:47 -0500, Mike Lockwood wrote:

>I like the idea of getting acquainted with testing as early as
>possible, so long as the results are only used to correct significant
>flaws in polishing technique, and the beginner mirror makier is not
>trying (pointlessly) to figure an unpolished mirror.

I'd second Mike that it's a good idea to test mirrors during early 
polishing, but not to try to "fix" things.  Just do a quicky Foucault 
test with a few zones, see what the surface deviations are from a 
parabola, then a spell with a fixed stroke (maybe one of the many, 
many suggestions), then test again to see what happened and put notes 
in a "pre-figuring" log.  By the time the mirror is completely 
polished, you'll be a figuring expert with tools really ready to fix 
things.  The trouble is there's so many variables (pitch softness, 
channeling, temperature, hand size <g>, default pressure, etc., etc.) 
that your situation is almost unique, then it gets really unique when 
the Strehl ratio gets up to ~ 0.7.

         -- Jim Burrows
         -- http://home.earthlink.net/~burrjaw
         -- mailto:burrjaw@earthlink.net
         -- Seattle N47.4723 W122.3662 (WGS84)

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