From: Kris Jones 
To: atm{at}shore.net
Reply-To: Kris Jones 


Good afternoon,

I am grinding my first mirror, and am finishing rough grinding and have
discovered that there is a small depression defect near the center of my
tool that is not grinding in a uniform manner relative to the rest of the
tool. Both the tool and blank are normal thickness pyrex blanks.

The mirror seems to be grinding in a uniform manner, and I have eliminated
any flat spot on the tool center and mirror edge, as described in most
guides to grinding a mirror. I have verified uniform wear by marking both
surfaces with a marker and monitoring over a few wets.

My concern is that this 1" x 1.5" kidney-bean shaped depression
"defect" in the tool , which is less than a 16th of an inch deep,
would cause problems later in the mirror grinding, smoothing and figuring
stages.

Should I ignore the defect, or should I continue to rough grind using a
centered stroke until the process naturally removes the defect? The mirror
& tool are both 12.5 inches in diameter. Any advice is greatly
appreciated.

Thanks!

Kris Jones
Santaquin, Utah.

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