From: "Jeff Baldwin" 
To: "Atm" 
Reply-To: "Jeff Baldwin" 


Masking a 10" scope to 9.5" is far better than a 10" scope
with TDE.  If you can't get it out, mask it.  If you CAN get it out, I'd
still mask or remove the outer 1/16".  A 9 15/16" scope with no
tde is a zillion times better than a 10" scope with tde.
Jeff Baldwin
Stockton  CA
W121d20.96m N38d01.62m
bald{at}gotnet.net
http://bald.gotnet.net/
----- Original Message -----
From: "CSC" 
To: "Atm" 
Sent: Sunday, February 09, 2003 5:29 PM Subject: RE: ATM Polishing from center


>
> Garth:
> Replacing a tool late in the fine grinding stage would create some
problems,
> I'd guess.  High or irregular tiles would plow the edge until they found
the
> curve.
>
> Reportedly, Jean Texereau believed that one could not reliably figure the
> edge, and recommended masking it.  Maybe 3/8" is more than he meant.
Either
> way you go, it will be a great scope.
>
> The edge cannot be left turned in the optical system, as it does affect
the
> image, and will spoil the view.
>
> colin
>
>
>
> -----Original Message-----
> From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of Garth
> Arsenault
> Sent: Sunday, February 09, 2003 9:34 PM
> To: atm{at}shore.net
> Subject: ATM Polishing from center
>
>
>
> I am in the process of building my first telescope. It will be a truss
> style Dob with a 10 inch f6 BVC mirror.  I am now polishing the
> mirror.  The mirror has polished out nicely from the center and has
> gradually polished out to within 3/8" from the edge. I have been
> polishing this mirror for about 14 hours.  I experienced rapid
> progress for the first 5-7 hours but have not noticed any progress
> for about the last 7 hours.  I understand that a sphere should polish
> uniformly across its entire surface.  I had to replace my glass tool
> about 3/4 way through fine grinding (Don't ask!) with a home made
> tile tool. Could this possibly explain what appears to be an
> imperfect sphere after fine grinding and leading to my problem with
> polishing.  I am looking for some advice on how to best proceed
> from here.
>
> Thanks!
>
> Garth Arsenault
>
> PEI, Canada
>
> arsenault{at}upei.ca
>
>
>

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