Re: [ATM] ritchey cretians

["Khail Rosenberg" <mikhail.rosenberg@rosenbergtelescopes.com>]

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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