Re: [ATM] Re: Ball bearing for triangles

["Jan van gastel" <jhm.vangastel@wanadoo.nl>]

I use piano wires (1.5 mm thick), placed at 90 degrees, in my 12 and 20
incher (both 2 inch thick mirrors) They work fine and without astigmatism.
The only thing I have to do, while collimating, is putting the scope in
vertical direction for a moment, to get the tension of the wires, and then
finetune the collimation.

Jan
http://home.wanadoo.nl/jhm.vangastel/Astronomy/

----- Original Message ----- 
From: "Raphaël GUINAMARD" <rguinamard@infonie.fr>
To: <atm@atmlist.net>
Sent: Sunday, September 05, 2004 9:34 PM
Subject: Re: [ATM] Re: Ball bearing for triangles


> > Your compliant edge supports seem good to me.  Question:  when you
install
> > the mirror in the cell...how do you know that when the mirror is at rest
> on
> > the edge supports...
> When I install the mirror, I push it slightly against the piano wire
> support.
> >the edge supports are somewhere in the middle of their
> > allowable range of flexure?...
>
> I don't understand exactly your questions.
>
> >how do you tell if the mirror has pushed the
> > edge supports beyond their useful limit of flexure?
>
> In fact, at the end of the laser collimation, and before the star test
> "ultimate" collimation I have to move (just a little bit) the piano wire
to
> get rid of constraints. Otherwise I have a big amount of astigmatism due
to
> the piano wire.
> In fact I'm not so happy of this piano wire because even when I move a
> little
> bit the piano wire, it's difficult to get rid of the astigmatism and I
have
> to move several time the piano wire. I think I'm going to upgrate on a
> different lateral
> support like this one : a caster (don't know if it's the correct
translation
> for the french "roulette") lateral support:
> on a 32" with astatic cell :
>
http://www.atmlist.net/contrib/rguinamard-at-infonie-dot-fr/600f3.3/MyFutureLateralSupport%3f%3f%3f/globalDevant.JPG
> detail :
>
http://www.atmlist.net/contrib/rguinamard-at-infonie-dot-fr/600f3.3/MyFutureLateralSupport%3f%3f%3f/RouletteCeinture.JPG
> on a 16" (ccaster in wood) :
>
http://www.atmlist.net/contrib/rguinamard-at-infonie-dot-fr/600f3.3/MyFutureLateralSupport%3f%3f%3f/Support%20miroir%20%e0%20roulettes%204%20%28floue%29.JPG
>
http://www.atmlist.net/contrib/rguinamard-at-infonie-dot-fr/600f3.3/MyFutureLateralSupport%3f%3f%3f/Support%20miroir%20%e0%20roulettes%201.JPG
>
http://www.atmlist.net/contrib/rguinamard-at-infonie-dot-fr/600f3.3/MyFutureLateralSupport%3f%3f%3f/Support%20miroir%20%e0%20roulettes%202.JPG
>
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