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Posted by dave hawkins/">dave hawkins on April 14, 1998 12:28:08 UTC

I`m having a little difficulty polishing a 2" secondary mirror for my 8" f4-15 dall kirkham.I`ve already gone back to fine grinding once,after fine grinding, a little polishing so I can see the rings I see two perfectly straight lines acroos the mirror,carry on polishing and progessivly these lines become more bent,and more of them. How do I decide if the miiror is concave or convex, If I push on the mirror in any place the rings move toward the center very slightly. I should have said I`m using the tool which I have checked for sphericity using the focault test, Any body HELP!! thanks in anticipation Dave

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