[ATM] New? Idea for mirror support

[sho at surfnetUSA.com (Steve Houlihan)]

Last week, Tom Krajci sent three links to this thread that dealt with three
different ways that professionals have used to solve this problem.  Did any
of you read them?  The first one he mentioned is a little hard to
comprehend, but uses a central support glued to the back of the mirror.  It
also has a counterweight to reduce the bending moment applied to the mirror.
I think this scheme has a lot of merit.

http://celt.ucolick.org/reports/report16_mirrorsegsupprt_mar01/report16_mirr
orsegsupprt_mar01.htm

Check it out.

Steve Houlihan
Santa Cruz, California

sho@SurfnetUSA.com
http://www.surfnetusa.com/sho
----- Original Message -----
From: "Andy Saulietis" <iss@pvtnetworks.net>
To: "Atm-List" <atm@atmlist.net>
Sent: Friday, February 13, 2004 2:59 PM
Subject: Re: [ATM] New? Idea for mirror support


> Doug asks, re supporing a mirror with a central rod:
>
>
>
> >Has anybody tried something like this?  Is this just another crazy idea
that
> >won't work?
>
> The mirror will be restrained radially as you suggest, but there will also
> be a moment (torque) applied to the back of the mirror, the amount
> dependiong on the
> elevation angle. This torque can deform the center of the mirror.
>
> Re mirror supports in general..I've found that there are no such
> things as 'rigid' materials..when trying to maintin geometries
> meaured in fractions of wavelenghths of light or arc seconds,
> *evrything* is made of jello..<g>
>
> I've supported perforated mirrors of 24-36" size using a central
> tube attached to the cell..the center support has to be located
> near the middle of the central hole so there's an equal amount
> of mirror weight both in front of and behind the support.
>
> I'v thought about restraining a mirror radially by attaching (with RTV)
> radial dovetail slots to the back of the mirror..these slots are trapped
by
> a radial mating bars, each mirror support point (9, 18, 27 etc) has
> one such slot/bar. The idea is that the mirror is now free to
> expand/contract relative to the cell structure. The slots/bars
> would have to have low stiction, but each one only carries a fraction
> of the total weight..thoughts? Probably an overkill but I'm beginning
> design of a 37" f4.6 alt-az & want to avoid the sling issues with
> this large & thin (2") mirror.
>
>
>
>
> Andy Saulietis
> ISS Enterprises
> 10 Milky Way
> PO Box 19
> Mayhill NM 88339
>
>
> World's first astronomy land development:
>
> http://www.pvtnetworks.net/~iss/starend1.htm
>
> 9 of 17 lots sold to astronomers as of 1/04
>
> 505-687-3067 voice/fax, call voice or e-mail to set up
> e-mail: iss@pvtnetworks.net
>
>
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/