From: "CSC" 
To: "Atm" 
Reply-To: "CSC" 


Ignore it.  Remember, the edge is where the action is.  On professional
laps, the center is often cut away. It may disappear when you go through
the grits or not.

Grind more, worry less.

Colin

-----Original Message-----
From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of Kris
Jones
Sent: Monday, June 30, 2003 4:23 PM To: atm{at}shore.net
Subject: ATM defect near center of grinding tool?



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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