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-   -   How much stretch in the blackout fabric? (http://www.avsforum.com/forum/23-screens/19889-how-much-stretch-blackout-fabric.html)

BrianMat 08-16-2001 07:44 AM

I am getting the materials this weekend to start on my screen. I have decided to use 1x3 fir strips for the frame and 1x2 fir for the stretchers. Not sure if the stretchers are necessary (seems to be a mixed bag on that on in this forum).

I have 104"x80" single panel blackout fabric. I figure that I can get the following by building a 4x3 screen:

4:3 = 104"x78" (130" diag)
16:9 = 104"x58.5" (119" diag)

The room is 20'x19'4" with a seating of about 15' (can be moved back)

My question is on the stretch factor of the fabric. It seems that everyone reports that it does stretch pretty well and I want to maximize my screen size. How much stretch can I expect from this size fabric? I would hate to loose that extra couple of inches http://www.avsforum.com/ubb/smile.gif

So, any problem with fir 1x3 vs. fir 1x4 and is 104"x80" a good idea?

Sorry for all of the questions on the forums. I am really anal on stuff like this. Someday when I am more of an HT expert I will actually post something worthwhile.

But, I will take lots of pics when I do this...

kal 08-16-2001 07:50 AM

Brian,

Not quite the same dimensions as you, but I bought blackout fabric that was 54" high to build my 96" x 54" screen. I was able to stretch the stuff to roughly 60" high - sufficient to staple it to the 1"x4" pine frame I had built. My biggest problem was that initially I didn't stretch & pull enough - I was afraid I'd rip it. I simply started pulling more & more and came to the realization that this stuff is super-strong and will put up with pretty much any abuse you give it.

Kal

------------------
BarcoGraphics 800 (1280x720@72Hz)
Silent HTPC DVD (RF modified GeForce2, Audiophile 24/96 for S/PDIF out)
8' wide 1.4 gain 16x9 painted fabric screen

BrianMat 08-16-2001 08:20 AM

Wow, a 6" stretch in 54" material? Wait, if you stapled behind the frame then you are talking about more than a 6" stretch, correct?

That is not bad. Hmm, maybe I can go even bigger (assuming the same extra 6"-10").

I see that you used 1x4 pine, but since the fir is more dense it looks like I should be OK with 1x3. Did you use stretcher bars or just a rectangular frame?


kal 08-16-2001 11:00 AM

Brian,

Nope, my viewable area is 54" high, so I stretched it to roughly 59-60" in order to staple it to the frame.

I used a couple of support beams in the middle of the frame - mostly to counteract all the stretching I was doing.

Kal

------------------
BarcoGraphics 800 (1280x720@72Hz)
Silent HTPC DVD (RF modified GeForce2, Audiophile 24/96 for S/PDIF out)
8' wide 1.4 gain 16x9 painted fabric screen

dhanson 08-16-2001 11:49 AM

Aside from stretcher bars, you might consider a solid backing, like 1/16 ply or MDF. That will prevent the frame from twisting in any direction as well as preventing the sides from bowing inward under tension.

I'm building my frame right now, and I started with 1 x 4 fir. I didn't think pine would have the torsional rigidity I'm looking for. But I'm not a carpenter and I'm not used to dealing with large pieces of wood so I'm trying to err on the side of caution.

But I guarantee a solid back would make your screen frame incredibly strong - this is how aircraft wings are made. The drawback is that it will be harder to replace the screen material if you build it so it's sandwiched between the frame and backing.


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