I'm in the final stages of completing a Torus style compound curved screen and thought I'd post about some of the trials and tribulations I have gone through to get to this point.
All in all it was a fun project. All I have left to do is actually staple on the screen material. The material is the Vutec PearlBrite 3.1 .I am hoping there will be no surprises! When I did a quick test with the material it didn't seem to have much gain, but I'm hoping that is because it wasn't tensioned. While testing the material I noticed that quite a bit of light passed through it so blacking out of the inside of the box would be very important. I ended up lining it with black velveteen just to be safe.
The screen itself is 108" by 54". The string method for determining curves came up with a pretty deep horizontal curve, so going by posts of other people who have built these, we compromised with curve depths of about 8.5 and 3.5 inches for H and V.
To control the screen depth I am using a limit switch to modulate a fan which draws a vacuum on the inside of the screen. This should work well along with the various voltage settings of the wall transformer. Since the idea is that the switch is put in such a position that when the screen is at the proper depth, it will hit the switch, turning off the fan, I wanted to find a switch with a very soft touch. Easier said then done! I did eventually find one.
For the sake of adjustment and replacement I made sure the limit switch, fan and wall transformer jack are easy to get to. The last thing I wanted was for the switch or something to fail with no way to get to it!
The hardest part of the project, other than finding time to work on it was dealing with the Canadian winter. Because of the size of the thing I had to build it in my garage (this one is not going into my theatre...). It's amazing how many materials such as glues, caulkings and paints say not to be used under 5 to 10 degrees Celsius. I must have a great wife, 'cause she let me keep the thing in our foyer for a week or so.
Anyways attached is a pic of the screen box sans screen material.