Re: [ATM] PVC fitting mirror-cell.

["Chris Rowland" <chris_group_mail@dsl.pipex.com>]

I have the secondary of my 8.75" Dob held to a PVC pipe with Silicone. It
has been there for over 3 years now. It is stored pointing up so the glue is
in tension all the time.

The secondary holder is made from a piece of 40mm PVC waste pipe with one
end cut at 45 derees and the other end square. The square end is glued to an
aluminium disk that holds the collimation screws, the 45 degree end has the
secondary glued on. All this is held together with RTV silicone, so I have
Al to PVC and PVC to glass glued joints.

The uPVC is sanded and I was very careful to degrease it - with surgical
spirit.

The primary mirror cell is made of plywood, varnished, and the mirror
attached with RTV.

If I were you I would try it. Sand a couple of spare pieces of PVC, clean
them and glue them together with a gap, as you will for the mirror.  Wait a
few days then try to get them apart.

Chris

----- Original Message ----- 
From: "Charles Mitchard" <charlesmitchard@iinet.net.au>
To: <atm@atmlist.net>
Sent: Sunday, April 18, 2004 7:52 AM
Subject: Re: [ATM] PVC fitting mirror-cell.


> PVC and silicone RTV do not mix. The bond if you are extremely lucky and
do
> not stress of move the items may last a week or so.
> Definitely do not use as the only fixing for the mirror or secondary if
> using PVC or in general most other plastics.
> As Kurt states, it peels off at the slightest excuse with no adhesive
> properties.
> Charles
>
>
> >What are the experiences of the list with silicone and PVC?
> >
> >Kurt
> >Nixa, MO
> >
> >
> >
> >
> >At 09:19 AM 4/17/04 -0500, Danny F. Barnes wrote:
> >
> >>Hi there,
> >>
> >>New to list and ATMing, starting with a 6" reflector. When it came to
the
> >>mirror cell, I made something out of PVC fittings, toilet flange
> >>floor-plate things. Seems like it will work, has this been done before,
> >>and if so, has it worked out? Is the PVC stable enough in varying temps
> >>to keep the mirror in collimation?
> >>
> >>Planning on attaching the mirror to the cell with silicon.
> >>
> >>Images are here:
> >>http://www.geocities.com/dannybarnes@sbcglobal.net/Desktop.html
> >>

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