Optical Supports new Mirror cells

[pmrid (Peter)]

Has anyone tried these?
http://www.opticalsupports.com/mirror_cells.html
They look well engineered and are quite light. The 12-12.5 inch versions weighs in at about 1.2 Kg only and they look extremely well made. Only thing I'm uncomfortable about is the way they secure the mirror in the cell. There are no mirror clips. Instead, it relies on a blob of silicone fixed on the edge of the mirror with the 3 brackets then tightened up onto it so the silicone flattens out. I'm putting a full-depth 12.5 inch mirror into one of these shortly (when the cell arrives from the maker) and am nervous about whether this system will hold the weight of a 43mm thick cell. They are pretty well priced too. The large size I have ordered plus US$50 or so freight will cost less than A$300 landed so it's not bad. Other positive is that it can accommodate a Cassegrain-style system as well - by turning out a suitable hole in the middle of the supporting plate. There is already a 92mm hole in the base plate giving plenty of room for making suitable connection systems to attach baffles, focusers etc.
Peter.

[Benno85 (Ben)]

I'm also curious on some feedback regarding these cells, as you say the price is quite attractive and appear to be quite light.

[Satchmo]

I think you are better of with flotation triangles and clips or to at least hold the mirror with a ring of silicon at the support zone . I can't see how the mirror can float properly on the supports when it is held from the edge like that. It would always be hanging somewhat from the edge. Mirror cells for large telescopes go to all sorts of lengths ( ie roller bearings , slings , teflon pads ) to stop a mirror hanging on its edge support.

[pmrid (Peter)]

Originally Posted by Satchmo

I think you are better of with flotation triangles and clips or to at least hold the mirror with a ring of silicon at the support zone . I can't see how the mirror can float properly on the supports when it is held from the edge like that. It would always be hanging somewhat from the edge. Mirror cells for large telescopes go to all sorts of lengths ( ie roller bearings , slings , teflon pads ) to stop a mirror hanging on its edge support.

Hi Mark. I hear you. I raised this with Curt (the designer of these cells) and I thought you might be interested in his response to me:
"I understand your concerns about supporting such a heavy mirror. This is in fact one reason why I do not make cells for 14.5" mirrors and up. IMHO flotation is a must from that point forward. There is some debate as to the necessity of a true flotation cell for a 12.5" mirror but I think this size represents a gray area in supporting various mirror apertures. I believe my 12" cell is adequate to support a full-thickness mirror provided the user takes care to apply strong adhesive at each vertical support AND between the mirror's bottom and the cell's upper plate (this whole process is described in the user manual). Adhesive placed on the bottom does not take the place of support points though. It merely fills the gap between, so the mirror's weight is still supported by the pads. Protostar actually uses a similar system with their secondary mirrors.

That being said, I would not discourage you from adding more support or security if you have the means."

I like the bit at the end - that's his insurance company talking I am guessing.

Peter