From: "Russell Jocoy" 
To: krjones{at}novell.com, atm{at}shore.net
Reply-To: "Russell Jocoy" 


>From: Kris Jones 
>Reply-To: Kris Jones 
>To: atm{at}shore.net
>Subject: ATM defect near center of grinding tool?
>Date: Mon, 30 Jun 2003 14:23:23 -0600
>
>
>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.
>

  ("atm{at}shore.net")

       Kris,

                Keep grinding, keep rotating mirror and tool in your normal
stroke and it will grind out.
   I would not go to the next grit until it does.  Make sure you are
rotating the mirror and tool opposite from each other if you are in a fixed
grinding position. If you are doing the barrel dance, rotate the tool,
or mirror opposite your rotation around the work circle..     Russ J.
("atm{at}shore.net")

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