AVS Special Member
Join Date: Apr 1999
Location: On a large overstuffed couch in Virginia Beach, Va
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I originally thought of a solid screen too. I think the radius would be different enough from either a balloon or dish that if you were going the solid route, the best bet would be to make the screen as we're talking above (vacuum method), then just lay it flat on the ground and use that as your mold for fiberglass.
I would want it to be light enough to handle, but sturdy enough to keep its shape. If your idea works, Tim, it should work as well with a "proper" shape (as per Don and Peter). The material in the "mold screen" could be chosen for shape characteristics only without regard to gain...ie cheaper, less stretch.
Once you have a mold, you could use that to form the "real screen". Perhaps even using standard high gain screen material laying face down over the initial mold, then smoothed carefully with proper stretch as needed, and sprayed from behind with the fiberglass to give support. Boats are done in this fashion, with the gelcoat (or finish coat) going on first.
If this works, it would be much easier to temporarily set the final screen material accurately in shape over a mold, and THEN make it fixed permanently into that shape ...rather than making the shape frame first, then trying to glue the viewing surface (the critical one) to the support surface without blebs, wrinkles etc.
I once was against the vacuum idea, but think it could actually be much more lightweight than fiberglass...even with a box frame. I do like the fact that once the fiberglass is set, the shape is fixed. OTOH with the vacuum idea, you could re-cut your frame sides and fine tune your curve.
The other problem with a solid screen is what to use for the surface. Gluing a standard high gain material to it would be very hard to do smoothly with the compound curve. And you would want a high gain...that's the whole point of torus. If KBK could come up with a 2-3 gain paint with good even characteristics then painting would definitely be best.
Todays homework, class, is to find out if a fiberglass or plastic material can be laid over the back surface of any commercial high gain screen material without damaging it. If resin doesn't
eat the material, I think the application would be smoother and more blemish free than gluing to a compound curve shape.
Next, everyone email Ken Hotte until he thinks of a suitable paint.
THEN, we have to pick a size that several of us can use!!!
I like Peters idea of getting info from him or Sigma...but really, if ANYONE with a home theater and high end CRT has already bought this from Sigma, etc., then the numbers would generally be usable to most of us...they wouldn't even have to start over.
They could sell us the specs from Jonathan $. Doe Esquire III, who has ABOUT the same screen and seating area size, and probably wouldn't care if we used the info if we just asked politely.
(God I hope the server isn't down after I typed all this!)
Finally went digital: RS20, ISCO IIIs, DIY 10.5' wide torus screen, Stewart StudioTek 1.3 G3 with 4 way masking and adjustable image size