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Re: [ATM] Tests of Surface Quality
Richard,
Thank you for your comments. I did not do any surface tests between grades
of abrasives, none whatsoever. I relied solely on the clock. 45 minutes to
an hour of each grade then clean up and move on.
My surface was pretty good before I began polishing. I've had good luck with
5 micron and 3 micron CeO before. I was not dissapointed this time either.
I've decided to call it good after seven and a half hours of polishing. The
surface is very clear. I cannot see any grey when I shine a high power
American Optical light ion the surface, even when I amplify the light with a
magnifying glass. I'm done.
I'm not concerned about the laser results at all based on what I am told by
others whom I respect such as Dick Parker. The test is too sensitive for
telescope purposes. I'm not even sure that what I am seeing are pits. But in
any event they are uniform from the center to the edge.
As this is the largest piece of glass I have ever handled by myself, I now
need to build a new test stand. I spent the afternoon at Lowes in Danbury CT
geting supplies to do so, and to do other things as directed by my wife.
Best regards,
Francis J. O'Reilly
----- Original Message -----
From: "Richard Schwartz" <richard1941@gmail.com>
To: <foreilly@verizon.net>
Sent: Saturday, September 22, 2007 1:47 PM
Subject: Tests of Surface Quality
> If you are dismayed by a red laser, DON'T TRY A GREEN ONE! You will
> go suicidal.
>
> I am curious what tests of surface quality you did before moving
> between grits and when moving from grind to polish. For example, did
> you do the red-out test? Were you able to look through the glass and
> actually see things as I do ? ( I have cataracts on both eyes, heh
> heh....) The fine ground surface should be no more frosty than
> frosty scotch tape.
>
> A common problem in fine grinding that results in pits is excessive
> pressure. The weight of your hand and the glass should be enough.
>
> You were wise to use 5 and 3 micron grit... many on the ATM list claim
> that those grits cause more problems than they cure, but I have had
> good luck with them. They certainly cut polishing time way down.
>
> That is all I can offer from my personal experience. Books do not
> always have the answers you seek, nor do those who pontificate from
> what they have read in books.
>
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