Re: [ATM] 8" Diagonal

[Mike Lockwood <melockwo@uiuc.edu>]

Hi,

Polaraligned wrote:
> Can anyone offer me an opinion on how thick an
> 8" diagonal should be?  Is 1.5" enough?

That's 8" minor axis, a little under 12" on the major axis, right?

I went to check the PLOP-derived designs already posted on the web, 
but the link is now broken.  I would consult those or run PLOP to get 
a feel for mirror thickness.

What is the design of the scope and where is the diagonal used?  If it 
is closer to the focuser the cell requirements can be relaxed a bit 
and the mirror can be thinner.

> Also, is silicone with safety clips the best bet for
> mounting? or is it too big for that.

We used silicone only (no clips so far) for our 5.5" minor axis 
diagonal in our 30".  The back was quite smooth, and was thoroughly 
cleaned before glueing.  We had to remove it from its mounting once 
and we had a heck of a time getting it to come loose.

They pick up gigantic mirrors using only RTV adhesive (I think that's 
the right flavor).

At some point I get concerned about flexure of the glue due to the 
weight of the mirror, and the resulting effect on collimation.

	Mike Lockwood

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