Re: [ATM] Is it possible?

[Mike Shuken <mikeshuken@value.net>]

Hi Ralph,

Go to http://www.atmlist.net/ and click search the achieves 2004 - 
present.  Type in my last name Shuken and go down to answer 18.  I 
asked the same question a few months ago and got several detailed responses.

Mike



At 03:57 PM 5/20/2006, you wrote:
>Hello all,
>I am new to ATM. My first experience was throwing a 6" ebay mirror in
>a tube and being surprised at what I could see. My second experience
>is involving getting an old 10" ebay mirror recoated and we will see
>how that does.
>
>But my post currently involves the following challange. I went out and
>bought an old 20" porthole ($28 total cost to me). I cut off the
>bronze frame and was pleased to find a nice chunk of 3/4" glass that
>was 16.5" in diameter. It is in prettys good shape with some surface
>scratches that I'm sure will grind out. No large internal bubbles
>although there are a few small ones near the surface... i am hoping
>these will grind out as well.
>
>Do you all think I have half a chance of successfully grinding this
>into a thin mirror if I use a cell with lots of points of support? I
>don't mind making it a long focal length to keep the center from
>getting to thin... This will be my first experience at making a
>telescope mirror. Am I being too ambitious trying to tackle a 16.5"
>thin mirror for my first experience? I think this is a motivating
>factor. How many hours will it take? 100?
>
>What is the lowest f-ration anyone would recommend this getting ground
>into? Have others had success grinding thin mirrors from 3/4" glass?
>
>I know I have alot of questions,
>Thanks,
>Ralph
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