Re: [ATM] ritchey cretians

["Jerry" <wa4guu@verizon.net>]

I would think that you would have all the answers to these many questions of
design, manufacture and testing already if you think you are going to turn
the optical industry on its head.

If you haven't learned and solved the difficulties of designing, producing
and testing large sophisticated optics, what makes you think that consumers
are being taken to the cleaners by those presently making such optics? And
what are you going to do differently that will cause you to win in the
competitive marketplace?

If anyone on this list knew those answers they would be doing it already
themselves.

Jerry




-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Khail Rosenberg
Sent: Sunday, January 20, 2008 11:33 AM
To: Bob May
Cc: atm@atmlist.net
Subject: Re: [ATM] ritchey cretians

Rather suprised by that Bob.... no auto collimation?

then what would you recommend? the benefit of collimating is that i plan on
doing it more than one time...

not too sure about the mirror design, i think for the sake of time, i am
already pouring it and dont really want a cell... anything thats going to be
48" especially an RC is not going to be too mobile, and to house it, i would
want to spend some money on for the controls.. making a lighter mirror will
take a bunch of time, and also no one at my shop (including myself) has made
this type of mold.... sadly..

let me know your suggestions for testing though...

On 1/19/08, Bob May <rmay@nethere.com> wrote:
>
> As is usual, when someting interesting comes along on the list,
> everybody has a bunch of good ideas.
> If you're going to be casting glass yourself, you might as well
> do a cellular mold ala the 200" Hale mirror.  Bob Goff had a 32"
> mirror blank from the company he had (Hextek) and it was light
> enough that a single person could pick it up.  Those things
> weren't cheap tho!  He did a fused proces in making the mirrors.
> As to handling the glass, the first thing is to make up a good
> strong band of steel with clips to hold the glass onto the band
> and not allow it to sli9p.  From there you can do any kind of
> attchment for lifting and otherwise moving it about.  I will note
> that having a building with a ceiling high enough that you don't
> have to tilt the glass off of the table in order to do the
> testing o at the ROC will be a plus if you don't mind walking on
> catwalks.  Otherwise, a tilting top for the grinder (you don't
> need to support the last few inches of the glass on the table!)
> will make testing easy.  Remember that you're looking at about a
> half ton of glass for the mirror.
> As to the flats, don't even try thin glass for them.  They will
> flex way too much with something that thin.  I won't say that
> autocollimation is out for a telescope of that size, but I'd
> rather look at all of the other tests before even contemplating
> such a test.  Even just finishing the telescope and pointing it
> at a star for star testing will be easier!
> Bob May
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