# Best pipe to use without sag for projection screen



## joecaption

PVC that long unsupported with nothing hanging on it would sag at that length.
It's also not UV protected and will get brittle over time if left exposed.
I might consider slipping in a piece of EMT tubing inside the pipe to see if that make it stronger.


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## SPS-1

If your pipe is 1.38" ID, then you more likely have 1-1/4" schedule 40 pipe.

Its going to easily sag 3 inches in the middle. Going to steel won't help much because of the added weight of the steel. Going to 4" pipe (4.5" OD) will help a little, but for a screen, you probably want zero sag.

Maybe you can put temporary supports under the pipe after unrolling it.

Or else perhaps run it over an edge (or rollers) that is absolutely rigid (as shown below. In the sketch below, the brown support can be as tall as necessary and have as many supports as you want.

(oops - In the sketch I meant to write weight on bottom of "screen", not "roll")


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## scampy74

Thank you both for your responses. I've been going around in circles trying to come up with an idea on how to make this work, as I don't have room to make a rigid support in front of the tube.

So far I've come up with this idea:



Cut a 1/4"-1/2" channel in a 3" PVC pipe that runs the length of the pipes (as well as a channel in the coupler).
To do this I'm planning on using my circular saw, two 2x6's, and my bench. I will turn the 2x6's on their side (6" standing up) and put the PVC pipe in between them and clamp them. This prohibits the PVC pipe from spinning while cutting, while also allowing me to place my circular saw on top of the 2x6's and slide it along as a guide. By being 3" above the PVC, my saw has no chance of slicing completely through the entire pipe, instead only being able to reach the top of it to cut my channel.

Attach 6 corner brackets to top of pipe and back of pipe (3 on each side of coupler), with the screws going into the eave and the wood of the house to provide support to the middle to prevent sagging
Slide 1-1/2" PVC pipe with the tubular motor inside of the 3" PVC, with the projection screen slightly hanging out of the pre-cut channel


Then, as the tubular motor rotates the inner PVC pipe, the screen can descend and ascend through the channel unobstructed.


The brackets on the top and back of the 3" PVC will provide structural support, but will not cover the channel to prevent the screen from descending and retracting.




What do you think? Will this idea work, or am I completely missing something that will blow this idea out of the water?


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## KarenStein

I solved a similar problem (though on a much smaller scale) by stiffening the PVC with a similar diameter metal rod inside.

For your use, I'd see if there was a size of copper tube or EMT that fit fairly close inside the PVC. I'd prefer copper, because of the smaller outside diameter of the coupling you'll have to use. Extend the metal beyond the ends of the PVC and support that; this will let the PVC spin freely on the support.

Sort of like this:

-)-=====-(-


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