Re: [ATM] ATM Dave Williams and his 3/4" x 20" attempt at aTelescopeMirror

["Bill Kelley" <flex@commspeed.net>]

Thanks Russell,

We all know that he is not likely to produce a fine optic, but dammit, he 
might make something that will make him proud of what he did. He clearly 
wasn't going to quit,  and after a flood of questions, many the wrong 
questions, he posted his original query all over again on the ATM site. It 
was time for someone to step in and lead him step by step as far as he was 
willing to go. He is now rebuilding his work station so there will be 
reasonable support for the mirror. It is many hours away from being polished 
out.

I agree with all of the caveats offered. I just finished a 13" X 3/4" plate 
glass sphere for some experimental flex work. I sweat bullets, spent months 
off and on, but finally got a lovely smooth null when the mirror is in 
temperature equilibrium.

I'll sometime soon  persuade him to make a small fast mirror that will give 
him some experience, and it will make an excellent finder for his big dream 
scope. I've lots of this stuff around from the classes we teach, and it 
won't cost me or him any thing for the materials.

I'm doing this by personal phone calls to him. As we make some progress 
worth reporting I'll have him post it.

David, hang in there. You have already been warned about the amount of work 
ahead, and the failures.  Don't let anyone discourage you. None of my 
students who were willing to stay the course ended up without a telescope of 
some kind. (not always the one they started on)Nor will you.

Bill Kelley

Subject: [ATM] ATM Dave Williams and his 3/4" x 20" attempt at a 
TelescopeMirror



>   Bill Kelly,   You are a saint to comming to the rescue of this newbie 
> who has already made
> his dive into the deep end of the thin glass pool. My first mirror attempt 
> was and still is 5/8"
> by 10".. I knew from the beginning that this thin glass needed support in 
> order to get a
> decent surface.  I  now have a sphere with a turned edge, this is quite a 
> feat for a first try.
>  To dive into a plate glass surface this thin , with a diameter way beyond 
> the limits, may be
> a lost cause.   I would suggest you get in contact with James Learch and 
> let his comrade
> Ron fill you in on getting anywhere from here. Ron produced an 18" x 3/4" 
> mirror with some
> success. I have been told when he figured this fun mirror he had to wait 
> 24 hours after 15 min.
> figuring session to even test. Plate glass likes to move all around when 
> your lap heats it up.
>   Many on the list have had nightmares with large pieces of plate glass. I 
> you are not experienced
> with the testing or the movement of the material on a large disk.. do a 
> small one first.   But thats
> too late. There may be a way to get to the end but Jerry Hillman will tell 
> you to throw it against
> a fire hydrant and start with some thing at least 1.625" thick for this 
> size...    Russ Jocoy
>
>
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>
> 


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