ATM Opinions needed

I'm new to this group and ATM'ing in general. I'm currently grinding a 14.5" f/6 mirror to go into a tube of my own design. I have searched the archives for info regarding attaching primaries to flotation cells with silicone. I found all of the info I needed but most of it was old but still relavent. A guy by the name of Tom Cathay *i think* attached his primary to a 27 point flotation with good results. I have tried sending mail to his AOL address but it no longer exists. Does anyone know how this worked out? I intend to mount my mirror this way but just wanted to see if there is any new info on this.

Does anyone know if Mr. Louis Wilkenson in Bell, CA is still making secondaries for amateurs? I have his contact info but would hate to call and find out that he has become disabled or worse.

About my tube design.......... I want to make a tube that will separate into 4 sections which will nest into each other when not in use. My design is loosely based on those collapseable camping cups. Why you might ask? Simply because I want to build something unique. The tube sections will be made by machining two aluminum rings for each end of the tube section. The tube itself will be made from carbon fiber, fiber glass, formica or similar material. It will be attached to the ID of the rings with countersunk screws spaced every 2" or so. The top tube section will be approx. 15.5" ID with each remaining tube section being successively larger so that each section will fit inside the next.

To connect each tube section I will need to have three more aluminum rings made that will bridge the size difference between each tube section. Each ring will attach to it's tube section in the same way that lenses mount to 35mm SLR cameras. The friends I'm working with on this agree that we can maintain the extremely tight tolerances needed to prevent too much free play. I also want to be able to rotate the top tube section with focuser 90 degrees to permit convienent ep placement. I understand that this will have to be done with extreme precision to maintain collimation but this detail can be left out if need be. I will have a leveling focuser base made in a dovetail design that will allow quick release of the focuser while alowing it to be replaced precisely each time the scope is set up.

My goals in designing this scope are high optical quality, uniqueness, compact light weight tube, extreme ridgidity and ease of use. I welcome any comments, criticism or other input I may have overlooked with this design. I will use this in "dob mode" until I aquire a large enough mount to permit using it for photography. My main drawbacks are expense, overly complicated design and lack of "stacks o cash" and a hard head!

1. What would be the best material for blackening the inside of the tube sections. Keep in mind that the sections will nest inside each other and I want to avoid marking up the inside of the tubes and the aluminum rings. I also do not want *stuff* falling on the primary like dust, paint chips........

2. What would be the best material for the tube sections? I was thinking about carbon fiber, fiberglass, aluminum or formica. I will install a rib on the *sky side* and *ground side* of each tube section to handle the the tensile and compressive forces associated with a tube this size.

4. Is there some other material I could use in place of the aluminum rings? A composite perhaps? It will need to have approx. the same characteristics as aluminum especially in strength and ability to maintain the critical tolerances of machining.

Bill Cotten
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