From: "Dwight K. Elvey" 
To: atm{at}shore.net
Reply-To: "Dwight K. Elvey" 


Hi
 It sounds like the new tool wasn't broken in properly.
I always recommend going back to at least #120 to break in a new tile
surface. Going through the grits doesn't take all that long.
 I'd have to give it some serious thought. If I really
wanted to get a good mirror, I'd go back to grinding. The fact that you
have such a wide band indicates that you have missed something in the
grinding. Although, others talk about TDE, you may find that you have more
than the 3/8" when you include any TDE that may be there as well.
Dwight


>From: "Garth Arsenault" 
>
>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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