Quote:
Originally Posted by Satchmo
Looks like you have done some research! My original 8" binocular used silicone squeezed fairly thin to mount all my optics and I eventually found them all to have been seriously warped by the thinly spread silicone causing quite a bit of astigmatism , which is why I suggested a minimum of 3mm.
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If you had more than three blobs of silicone or a single large area then that would constrain the glass and likely cause astigmatism. By having just three blobs this would allow any of them to shrink / swell without straining the glass (assuming the blobs are not too large as then you would get differential pressure across each blob).
No one has any suggestions for the type of silicone? Then I will probably test Selleys Glass Silicone - it appears to be low modulus (high flexibility) so I will try a thickness of 1mm for three points. My great fear is that the silicone gives out and the secondary falls off!
Selleys Glass Silicone appears to provide the most secure bond for glass (and hopefully carbon fibre / epoxy resin). I had originally thought that I should use a neutral cure, but I don't think this is necessary since it is not coming into contact with metal.