Re: ATM Re: flexed shaped-back null

["William Kelley" <wekelleylwk@sedona.net>]

Frank- No hole in the mirror for the puller- bolt is epoxied to the 1" stud,
Shaped-back tapering
to the edge as as per a flex program provided by Alan. A bolt glued to the
center of a flat-back blank will only produce less than a 4 times
improvement on a sphere. A 6" F8 sphere thus becomes about a 1/12 wave
parabola. A good newbie scope that is easy to make.  Regards  -  Bill


Subject: Re: ATM Re: flexed shaped-back null


>
>  Bill,
> Sincere, heartfelt congradulation,
>
> I never doubted the quality of the parabola you could
> produce, but then I don't have a vested interest in
> any method of obtaining one.
>
> Question: Alan Adler uses a central plate of aluminum which is
> fixed to the flat back with epoxy and a rubber "pressure"
> compensator. He then runs a carriage bolt thru a hole to
> a second plate fixed to the edge with a ring of rubber.
>
> How does your formed back differ. One,are you still epoxying
> a carriage bolt into a hole in the center of the blank which
> has a tapered surface to a thinner edge.  Two,are you also
> using a ring of rubber and a back plate for your pressure?
>
> If you are, then you are trading the puller plate for a fixed
> stud and a tapered back, correct?  Since a tapered back
> is in the commercial field, could we get equal results with
> a fixed stud in a flat back with a pusher plate and the
> rubber ring? Or, lastly, is the quality dependent on the taper
> which allows the glass to flex uniformly with less pressure?
>
> With friendship,
>
> Frank Ward
> Atlanta, GA
>
>