How To Question

Hello fellow telescope builders, I wanted to tap the resource before committing to attaching my mirror to its mirror cell. I have a Novak 10” 9pt floating mirror cell with 3 hold down clips and a 2.5” thick glass mirror. Weight of the mirror is 15lbs.

In discussions with other’s as to how best to attach the mirror, some have said to remove the hold down clips and glue the mirror to the side arms. Others have said to glue the mirror down to the floating “plates”. And some have said to glue to both floating plates and side arms.

What is the best proven way to do this.

This is for a 10" newt, f5.5 ota.

Thanks, Don

Glued to the floating plates is the most used method that I know. Silicone glue is used in small amounts. All that you gain is you are rid of the clips and any spikes created by them.

If I may chime in, I've been contemplating doing this for my 8" scope which also has a Novak nine point cell. The problem with the clips is that it is difficult to get them spaced and set correctly to hold the mirror securely while avoiding pinching it. I’ve found that the way I have it now is OK as long as the weather is warm, but in cold weather the mirror is pinched. My guess is it’s because it’s a Pyrex mirror (very small COE) in an aluminum cell (relatively high COE). So I’ve been contemplating gluing the mirror in, eliminating the clips, but I don’t like the idea of gluing, which can create problems when you want to clean the mirror or have it recoated.

Something I’m now considering is eliminating the clips and holding the mirror down using Velcro as shown in the picture. It’s from a homemade cell made by Lee Stock (hope he doesn’t mind me using his picture.) There would be no need to glue in the mirror in this case - the triangles could just float.

Food for thought.

Doug

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