Re: [ATM] Rebuilding the mirrorcell

["Bob May" <bobmay@nethere.com>]

I might remind you that the "old" system of mounting the mirror with 3
points at the 70% zone (you should use the 40-45% zone now) and 3 posts
around the mirror equally spaced with a tab over the top of the mirror
surface to hold the mirror in place worked well for a large number of years.
Don't forget to insure that there is some clearance to the posts (1 business
card thickness is fine on one of the posts wth the mirror sitting snug
against the other two posts) from the mirror as well as that much for the
space from the mirror's top surface to the overhanging tabs will hold the
mirror more than well enough for a continous good alignment.  In fact, if
there is roughness on the back surface like there is with a lot of the
castings for pyrex mirror blanks, it would be better to glue one of the
support points to the mirror so that it doesn't move or make small holes for
the points to stay in.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net
----- Original Message -----
From: Treur, Harro <H.Treur@wlb.amsterdam.nl>
To: 'Bob May' <bobmay@nethere.com>
Sent: Thursday, November 11, 2004 11:23 PM
Subject: RE: [ATM] Rebuilding the mirrorcell


> Hello Mr.May,
>
> I realize that mirrorsupport and Plop have got nothing to do with the
> collimationproblems.
>
> The mirrormovement is only the reason (for rebuilding).
> But in my rebuilt I don't want to make things more complicated than
> necessary. So if a 3 point system  is sufficient, why should I bother
making
> a 9 point?
>
> Best regards
> Harro Treur
>
> -----Oorspronkelijk bericht-----
> Van: Bob May [mailto:bobmay@nethere.com]
> Verzonden: donderdag 11 november 2004 17:59
> Aan: atm@atmlist.net
> Onderwerp: Re: [ATM] Rebuilding the mirrorcell
>
>
> What is the problem?
> The number of points on a cell just tells how accurately the surface is
> going to be held and not anything to do with collimation of the mirrors.
If
> the primary is moving about in the cell, that is something else. Bob May
> bobmay@nethere.com http://nav.to/bobmay http://bobmay.astronomy.net
>
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