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Re: Need Help With 6" F/8 Mirror Blank

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Posted by Kenneth Blackburn/">Kenneth Blackburn on February 22, 1999 02:02:02 UTC

I have a rather interesting problem. My father started grinding a 6" f/8 mirror blank some 40 yrs ago. He gave me the blank and tool around 9 years ago. I finish ground the blank, tested for radius of curvature using focault test, finish polished the blank then parabolized the blank. Before I was able to send the blank out for coating my father nad I had a disagreement and he asked for all of his things back. In January of this year he brought me the blank back. I began work on the scope again and was preparing to send the blank out for coating. On a whim since it had been so long since testing I placed the mirror blank in its cell and the tube and viewed the moon with it. I was not able to bring the moon into focus at all. Which leads me to believe I made errors in my original tests. Where would be the best place for me to start in determing what my problem is? Thanks for any input.

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