From: "Russell Jocoy" 
To: jhisson1{at}columbus.rr.com, atm{at}shore.net
Reply-To: "Russell Jocoy" 


>From: Jason Hissong 
>Reply-To: Jason Hissong 
>To: atm{at}shore.net
>Subject: ATM Chips on the side
>Date: Mon, 14 Jul 2003 08:29:25 -0400
>
>
>Hi guys,
>
>I got my ROC to the proper length for my 6" mirror, however, when I was
>using longer strokes to lengthen the ROC, some chips formed at the edge.  I
>pretty much ground them out so that it would not cause anymore damage,
>however, my mirror is not completely round.  Does this matter? (i.e., the
>bevel is wider at the spots that the chips were on the side.)  It is still
>pretty much a 6" mirror.
>
>BTW... I recently purchased this spherometer:
>
>http://www.tjanstrom.com/spherometer.html
>
>And it works great.  Thanks Thomas!
>
>Thanks!
>
>Jason Hissong
>
>

("atm{at}shore.net")

   Jason,

   You need to explain when you say your mirror is not round, I'm sure all
who were reading your listing
had visions of astigmatism from the start of your process. If you mean your
bevel grinding is off center
don't worry , when you move out to a sphere with your grinding your bevel
will be different widths.
    From what you say you have grinded all the way to the edge elimnating
the bevel ( if you did bevel
the glass?) and when you have a sharp edge the tool tends to chip the edge
since it becomes knife
like.  Glass does not like sharp edges pushed into, only away from (when
grinding straight on or
horizontal)  I am not sure but I think that even when grinding
"flats" that a slight bevel is necessary on
the outside of the flat.
       If your glass is not round by at least 1/4" in diameter , you need to
fix this.  Even though this will not cause major problems if your rotation
and grinding is all in sinc.  you will end up with a larger reveal
on the glass since the grinding and rotation tend to grind a true circle...
if you are rotating the tool and
glass properly. I noticed 1/16" differences on my bevel of my mirror
after all my grinding since I am the
one who rounded the blank by primative means..
                                Russ Jocoy
("atm{at}shore.net")

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