Re: [ATM] PVC fitting mirror-cell.

[Kurt Clement <kurt.clement@flashmail.com>]

Looks like you are making good progress.

I have had mixed results with PVC and silicone on a number of 
projects.  Even if you sand the PVC, the silicone seems to peel right off 
with little adhesion.  I am making my secondary holder from PVC and have 
done some experiments on PVC and adhesives.

Silicone does not adhere well to PVC, sanded, smooth, or preped with acetone.
Epoxy adheres well to sanded PVC.
Silicone adheres well to smooth epoxy.

My plan is to sand the portions where the silicone will go.
Apply a thin smooth layer of slow cure epoxy and let it cure for 48 hours.
Set up three toothpick spacers and apply three dabs of silicone between them.
Cure the silicone, remove the toothpicks, apply a bead of sillicone all the 
way around the secondary, forcing it into the gap left by the toothpicks.

Do some experiments of your own before trying it on your mirror.  A spare 
PVC coupler or short pipe section could be used as the test 
surface.  Whatever you test, clean the PVC with a solvent first.

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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