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Discussion Starter · #1 ·
Hi everybody.:)

Amateur musician and bored nerd soliciting your sageness. I dove in head first here in my small apartment with 11.1 and now that the projector and screen are temporarily installed, I have some issues, of course.

I just started looking into this setup a couple years ago. Until then my DIY experience was mainly limited to component-level troubleshooting (I is enganeer of course). Besides a couple of very simple systems I installed for family and friends, my home theater experience is limited to what I have done here in my apartment.

My front towers are blocking the wall. I bought a used Elite Screens Spectrum AT Electric100H-A1080P2 and found it has a severe moire problem with the BenQ HT1075. Acoustically the transparency seems fine.

Not really surprised based on my prior reading but the moire is worse than I imagined. At least the curls and waves are not too bad yet. Maybe it will work out for a year or two before it self-destructs.

It works well enough for now but I would like to be rid of the streaky lines someday (without being rid of the projector too).;)

I did some reading and discovered the Spandex threads.:cool: Little nerd wheels start grinding away inside wondering if there is a good solution to this problem.

Can I put a layer of Spandex and some tensioners on this screen? Can I replace the screen material entirely with something that has no moire? This place is an experimental home theater so I am willing to remove and remount the guts of the screen roller and motor assembly on a board to make room for larger diameter when rolled up.

I might even be willing to start fresh with a piece of pipe and a hand crank, if I can save $$$ off the price of a high grade screen and get similar results. Can I?

My manual skills are OK but my strength is not so good. Any DIY will need to be done with minimal hand tools and maybe an electric saw and definitely not requiring any precision beyond what average person can accomplish without a workshop.

Should I just build a fixed screen on the wall? Buy a better retractable AT screen? What will it cost me?

Issues with fixed screen are that the screen increases from 100" in front of the speakers to 130" on the wall and the LCD has to go somewhere else (but where?). Since the stove is only about 10' away from the edge of the screen and I keep the windows open for half the year, dust and grease are also an issue. Whatever screen I have in here either has to retract or be washable.

I am mounting the projector on the ceiling so that the top of the screen will be similar height regardless of whether it ends up in front of the towers or on the wall.

I have a dark bedspread on the front wall temporarily. Some day I hope to put absorber panels in (probably DIY) so regardless of screen type it should be AT or part of a sealed absorber. Not interested in making the rear wall the 'dead wall'. Want the 'dead wall' to coincide with the screen that will be there plus the sectional sofa already blocks a third of the rear wall anyway.

That is, unless someone convinces me otherwise. Right now I am fairly exhausted from this build. I spent 2 years shopping for used equipment to make this system happen. So far, I am pleased with just about everything except the moire.

Your opinions? Thx.
 

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Lots to deal with....

First, resurfacing the Elite is not an option as the spandex would not be a good stand-alone material for such a Roller assembly.

Overlaying the Elite material would also be at best a Problematical solution, as the spandex, not being attached across the surface, would almost assuredly bunch up during retraction.

Building a Fixed spandex Screen seems most likely, as it does not involve much expense or any real effort, it's visual and audio performance is excellent (...but comes in at a lower gain than the Elite...) and a slightly smaller screen that looks good is better than a bigger screen whose appearance is annoying.

Dust should not be an issue. But if your cooking involves a lot of frying in close proximity...well, that's a pretty intractable issue there.

TV wise, moving it is the simplest fix. Maybe not the most desirable, but the easiest to effect.

Morie is always a consideration with AT screens whose weave is too open or aggressive. I'm sorry your own research prior the purchase to failed to discover that.

But one possibly easier yet effective solution would be to change the angle of the PJ's beam as relates to the angle of your viewing, and instead use Keystone adjustment to square the image.
 

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Hi everybody.:)

Amateur musician and bored nerd soliciting your sageness. I dove in head first here in my small apartment with 11.1 and now that the projector and screen are temporarily installed, I have some issues, of course.

I just started looking into this setup a couple years ago. Until then my DIY experience was mainly limited to component-level troubleshooting (I is enganeer of course). Besides a couple of very simple systems I installed for family and friends, my home theater experience is limited to what I have done here in my apartment.

My front towers are blocking the wall. I bought a used Elite Screens Spectrum AT Electric100H-A1080P2 and found it has a severe moire problem with the BenQ HT1075. Acoustically the transparency seems fine.

Not really surprised based on my prior reading but the moire is worse than I imagined. At least the curls and waves are not too bad yet. Maybe it will work out for a year or two before it self-destructs.

It works well enough for now but I would like to be rid of the streaky lines someday (without being rid of the projector too).;)

I did some reading and discovered the Spandex threads.:cool: Little nerd wheels start grinding away inside wondering if there is a good solution to this problem.

Can I put a layer of Spandex and some tensioners on this screen? Can I replace the screen material entirely with something that has no moire? This place is an experimental home theater so I am willing to remove and remount the guts of the screen roller and motor assembly on a board to make room for larger diameter when rolled up.

I might even be willing to start fresh with a piece of pipe and a hand crank, if I can save $$$ off the price of a high grade screen and get similar results. Can I?

My manual skills are OK but my strength is not so good. Any DIY will need to be done with minimal hand tools and maybe an electric saw and definitely not requiring any precision beyond what average person can accomplish without a workshop.

Should I just build a fixed screen on the wall? Buy a better retractable AT screen? What will it cost me?

Issues with fixed screen are that the screen increases from 100" in front of the speakers to 130" on the wall and the LCD has to go somewhere else (but where?). Since the stove is only about 10' away from the edge of the screen and I keep the windows open for half the year, dust and grease are also an issue. Whatever screen I have in here either has to retract or be washable.

I am mounting the projector on the ceiling so that the top of the screen will be similar height regardless of whether it ends up in front of the towers or on the wall.

I have a dark bedspread on the front wall temporarily. Some day I hope to put absorber panels in (probably DIY) so regardless of screen type it should be AT or part of a sealed absorber. Not interested in making the rear wall the 'dead wall'. Want the 'dead wall' to coincide with the screen that will be there plus the sectional sofa already blocks a third of the rear wall anyway.

That is, unless someone convinces me otherwise. Right now I am fairly exhausted from this build. I spent 2 years shopping for used equipment to make this system happen. So far, I am pleased with just about everything except the moire.

Your opinions? Thx.
I doubt you could do anything with that existing Elite case and mechanism except sell it onwards to recoup your money.

This http://www.avsforum.com/forum/68-di...69-apartment-setup-guidance.html#post29617650 is an example of someone using two layers of miliskin spandex stretched between clips attached to the walls, ceiling and floor with bungees. White over black and using a W1070.

Obviously, it lacks borders and aesthetics and is not as convenient as a retractable rollup screen but in terms of picture quality it should be no different than if it were permanently stretched across a fixed frame. It will not be as EVENLY stretched because on a fixed frame the stapling or screen-tite fastening would be providing almost continuous tension. But it might give you some ideas on how you could use spandex on other than a fixed frame. Possibly with a curtain rod along the top and bottom (weighted to provide vertical tension) and clipped every 6 inches to the glides in the rods while stapled to solid vertical sides, so it could be drawn off to one side of the TV area like a curtain, then drawn across and hooked so it was held under horizontal tension. With the curtain rods (not really rods but those tracks I can't think of the name for) behind wide black velvet wrapped boards top and bottom and the vertical sides the same, you could end up with a very nice looking retractable spandex screen with sharp black borders.
 

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Discussion Starter · #4 ·
Lots to deal with....

First, resurfacing the Elite is not an option as the spandex would not be a good stand-alone material for such a Roller assembly.

Overlaying the Elite material would also be at best a Problematical solution, as the spandex, not being attached across the surface, would almost assuredly bunch up during retraction.

Building a Fixed spandex Screen seems most likely, as it does not involve much expense or any real effort, it's visual and audio performance is excellent (...but comes in at a lower gain than the Elite...) and a slightly smaller screen that looks good is better than a bigger screen whose appearance is annoying.

Dust should not be an issue. But if your cooking involves a lot of frying in close proximity...well, that's a pretty intractable issue there.

TV wise, moving it is the simplest fix. Maybe not the most desirable, but the easiest to effect.

Morie is always a consideration with AT screens whose weave is too open or aggressive. I'm sorry your own research prior the purchase to failed to discover that.

But one possibly easier yet effective solution would be to change the angle of the PJ's beam as relates to the angle of your viewing, and instead use Keystone adjustment to square the image.
I was aware of the limitations of the Elite. I just had no actual experience with it. My only other screen attempt was a blackout cloth on a portable wooden frame made with dirt cheap and simple hardware including stick pins and elastic straps and felt. Amazingly enough, it worked well enough to get used.

One aspect of my HT is that I am compromising on quality to try out features. Projector with 11.1 in decent sounding transducers basically mandated serious compromises.

So I compromised on quality to get a leg up on implementation. This AT screen just happened on Craigslist at a price where the actual investment is best considered an education as well as a shortcut. I knew if I passed on it the chances of seeing it again were small.

This way I at least verified that an AT screen works very well acoustically in my room. I did not even recalibrate and it seems the additional damping of the screen material or its reflectivity or whatever has slightly improved the sonic character of the room in some way.

Maybe it is because the weak center speaker is below the screen. It has a more direct route into the listening space so maybe that helps it compete for attention.

That may change somewhat after the projector and screen are mounted. I have not yet figured out the height and just hung the screen from cable. I also have a better center speaker on the way.

Actually despite my surprise at how strong the moire is, I have to say the picture looks awesome at 100" from 6.5'. The colors are dead accurate and the brilliant rainbows are becoming as automatic as the gentle hiss of tape and the wharpy whoofy tick of vinyl.:)

So in regard to the option of spandex, I come down to this ultimate limitation. No matter what I do, cooking is going to taint it unless I find a way to protect it. I can cover it or I can retract it or whatever but what I cannot do is leave it somewhere that it can have the grimy dust of a dirty oven smoking on it.

I really hate the thought of moving the TV every time I want the screen. Too risky to the TV and to me.

What about a frame that works the same way a partition in a conference room works? Spandex should easily fold up into a square tube-shaped cabinet on the side of the room. Then I can just extend the partition in front of everything, hang it on a hook on the opposite end of the room and voila, instant AT screen.

Anybody know how to construct such an animal?
 

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Anybody know how to construct such an animal?
While I don't really know about that particular way of making a folding spandex screen, Dreamer recently drew-up what looks to be a very sound folding option that might work for you.. gimme a second.
... not precisely to scale. Rotate the drawing 90 degrees left. Top pic is the frame in a partially collapsed stage, bottom is in full width with straighteners attached. I did not show the fully collapsed stage which would just be 10 thicknesses of the 1x3s on edge. Because the 6 segments are each only 1/6th the width of the frame, even on a 2.40:1 ratio screen the top and bottom segments will not prevent complete collapse because each is less than half the frame height. The dowels on vertical pieces combined with the horizontal segments provide gusseting of the corners to hold it square. 1x3 wood for frame on edge and 1x4 wood on the flat for the straighteners. I would expect dimpling of the spandex around the hinge points, which is why I suggested making the screen 8 full inches taller than the viewable area so 4" high sleeves of black velvet would cover top and bottom and hide those dimples.
 

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Discussion Starter · #6 ·
Nah mebbe not. Too much gravitational force to fight with a jointed frame. It would need a track at ceiling height to support it anyway.

What about a pipe roller along the ceiling and a weighted bar on the bottom of the screen. Then I just need to figure out the mechanics of translating the rotational force from the pipe down to shoulder level. Another pulley is involved as well as an anchor point. Built-in bookcase... clamp... brake... what about the brake? The Elite has the ability to stop in any position. I need friction.

So now I also need the screen material. I saw some threads about Spandex and a few other AT materials. There is a product available on Amazon where they just ship something and cinegrey AT might have been on that list. If I put in a roller I do not really need the elasticity of Spandex at all. Options open up.

Tensioners, well that is a different story, I definitely need tensioners. How do I make tensioners?

What about a super-light, minimally tensioned Spandex screen with super-light tensioners?

Oh now I see, you suggested the frame on either side to tension it on the sides. How would I make that adjustable in height? The projector only has about 3" of lens shift and it is a screw mechanism that obviously cannot withstand much repeated stress or do much adjustment. That limits my flexibility in where to take up the slack.

Also I have not got the projector mount yet. It seems the attachment must be to the wall. There is acoustic spray on the ceiling and it makes a mess if I look at it too hard.

Almost every mount I see is ceiling not wall. The one wall mount I did see was less than impressive and presents challenges in positioning. I prefer to attach at the header plate where I can center the projector exactly without having to hunt for studs. A thin metal shelf at ceiling height would make a good attachment for a ceiling mount... drill though the angle at the corner of the bracket... sink one screw into each of two such brackets...

For $100 there seems to be a fairly good ceiling mount available with adjustment wheels and set screws. There are also others for le$$ with just a swivel or an aluminum extender tube and U brackets but they look clunky. There could be a DIY solution that I am already halfway to just because I already have a thin metal attachment plate in the plan at the ceiling anyway. Thoughts?
 

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Discussion Starter · #7 ·
OK here is another iteration in the brainstorm.

I think the problem with retracting on a roller is that Spandex needs similar strength in the frame on all sides to apply tension in both axis evenly.:confused: The material cannot hold its own shape so it needs some limit on its stretch in the vertical direction from the weighted bar at the bottom while adding some additional pull horizontally to keep it taught in that dimension.

How about a ceiling roller system similar to the Elite but with the addition of extra weights on the bottom bar and a set of non-stretchy vertical edge cords? I suppose the horizontal tension may diminish when the thing rolls up and friction takes over from gravity, but at least while it is down it should be OK? Maybe some tablike tensioners can help even it out while it is rolled up without needing to be strong enough to support the entire load themselves when it is down?

Just how much tension does Spandex need?:confused:
 

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The spandex is probably one of the least-tensiony (
 

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OK here is another iteration in the brainstorm.

I think the problem with retracting on a roller is that Spandex needs similar strength in the frame on all sides to apply tension in both axis evenly.:confused: The material cannot hold its own shape so it needs some limit on its stretch in the vertical direction from the weighted bar at the bottom while adding some additional pull horizontally to keep it taught in that dimension.

How about a ceiling roller system similar to the Elite but with the addition of extra weights on the bottom bar and a set of non-stretchy vertical edge cords? I suppose the horizontal tension may diminish when the thing rolls up and friction takes over from gravity, but at least while it is down it should be OK? Maybe some tablike tensioners can help even it out while it is rolled up without needing to be strong enough to support the entire load themselves when it is down?

Just how much tension does Spandex need?:confused:
Did you read post#3 ? In the same thread I referenced, Jim mounted his W1070 to the underside of a shelf up high on his wall following my instructions. It worked fine with just a shelf, no separate mount.

In my suggestion of a curtain rod/track at top and bottom the vertical tensioning is obvious and probably just the weight of the board at the bottom to create a border would be enough. The vertical side pieces would provide the horizontal tension with one side permanently attached to the top and bottom boards and the other hooked to the top and bottom boards when it was pulled taut. The frame would always be in place, and to watch the TV, the fabric section would be drawn aside.

You had not mentioned a need to stop the screen at a particular height, and I wouldn't do that. I would simply have magnets glued to the vertical side pieces under the velvet and make some separate black velvet masking panels with staples or thumbtacks on the backside -- neodymium magnets would be enough to hold panels of black velvet covered luaun or foam or cardboard in place.

Trying to reinvent the tab-tensioned roll-up screen would require very narrow profile connections to the spandex for it to roll up onto a pipe at all. Using the tarp clips I suggested and that Jim uses would be far too bulky to roll up. Using them to the frame idea would be easy and would make the spandex removable and washable is it gets dirty. The miliskin is intended for clothing so I assume it is machine washable.
 

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Nah mebbe not. Too much gravitational force to fight with a jointed frame. It would need a track at ceiling height to support it anyway.
Actually, I designed that jointed frame as a free-standing one -- no attachment to the ceiling required at all. The straightener plates attached to the back mean it is not "jointed" at all when it is set up -- everything is locked into place by the dowels and holes. They gusset the four corners and the verticals are solid, so I don't understand the gravitational force concern. It was designed to be portable and quick to set up, but not as easy for everyday use as the one I described in post#3.
 

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Discussion Starter · #11 ·
Tried the keystoning thing. I lowered the projector by a couple inches and aimed it upward.

The moire did not diminish at all. It just took on a curve.
 

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Discussion Starter · #12 ·
Did you read post#3 ? In the same thread I referenced, Jim mounted his W1070 to the underside of a shelf up high on his wall following my instructions. It worked fine with just a shelf, no separate mount.

In my suggestion of a curtain rod/track at top and bottom the vertical tensioning is obvious and probably just the weight of the board at the bottom to create a border would be enough. The vertical side pieces would provide the horizontal tension with one side permanently attached to the top and bottom boards and the other hooked to the top and bottom boards when it was pulled taut. The frame would always be in place, and to watch the TV, the fabric section would be drawn aside.

You had not mentioned a need to stop the screen at a particular height, and I wouldn't do that. I would simply have magnets glued to the vertical side pieces under the velvet and make some separate black velvet masking panels with staples or thumbtacks on the backside -- neodymium magnets would be enough to hold panels of black velvet covered luaun or foam or cardboard in place.

Trying to reinvent the tab-tensioned roll-up screen would require very narrow profile connections to the spandex for it to roll up onto a pipe at all. Using the tarp clips I suggested and that Jim uses would be far too bulky to roll up. Using them to the frame idea would be easy and would make the spandex removable and washable is it gets dirty. The miliskin is intended for clothing so I assume it is machine washable.
Sorry, I did not read the entire thread, just skimmed it.

OK now it is clearer just from your description that the frame is always in place but hanging in midair and opens like curtains to watch the LCD with adjustable mask on magnets and curtain rod action side to side. Got it. I had visualized it being on the wall not in midair all the time. That does get a little awkward in here because of the cramped space but this setup is all about compromises.

Thanks for the help. I need to digest the input now.
 

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Did you read post#3 ? In the same thread I referenced, Jim mounted his W1070 to the underside of a shelf up high on his wall following my instructions. It worked fine with just a shelf, no separate mount.

In my suggestion of a curtain rod/track at top and bottom the vertical tensioning is obvious and probably just the weight of the board at the bottom to create a border would be enough. The vertical side pieces would provide the horizontal tension with one side permanently attached to the top and bottom boards and the other hooked to the top and bottom boards when it was pulled taut. The frame would always be in place, and to watch the TV, the fabric section would be drawn aside.

You had not mentioned a need to stop the screen at a particular height, and I wouldn't do that. I would simply have magnets glued to the vertical side pieces under the velvet and make some separate black velvet masking panels with staples or thumbtacks on the backside -- neodymium magnets would be enough to hold panels of black velvet covered luaun or foam or cardboard in place.

Trying to reinvent the tab-tensioned roll-up screen would require very narrow profile connections to the spandex for it to roll up onto a pipe at all. Using the tarp clips I suggested and that Jim uses would be far too bulky to roll up. Using them to the frame idea would be easy and would make the spandex removable and washable is it gets dirty. The miliskin is intended for clothing so I assume it is machine washable.
I can agree that really anything would be easier to make (and harder to screw-up) than a full TT rollup..not to mention the rollup would be near impossible to clean if needed.

Tried the keystoning thing. I lowered the projector by a couple inches and aimed it upward.

The moire did not diminish at all. It just took on a curve.
It would've been great if it worked in this case (who doesn't appreciate a free fixit), but at least you tried it before doing anything elaborate first only to find it may have worked later..

I wonder how much difference the rollup actually makes for keeping the screen clean compared to having it out or simply moved elsewhere since the size and weight isn't too ginormous.
 

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Discussion Starter · #14 ·
Actually, I designed that jointed frame as a free-standing one -- no attachment to the ceiling required at all. The straightener plates attached to the back mean it is not "jointed" at all when it is set up -- everything is locked into place by the dowels and holes. They gusset the four corners and the verticals are solid, so I don't understand the gravitational force concern. It was designed to be portable and quick to set up, but not as easy for everyday use as the one I described in post#3.
I see, the holes on the drawing describe the interlocking pins between the folding section and the straightener section. So the folding section is what, hinged? That means hinges on front and rear of the frame or at least recessing the hinges but no matter how it is done some of the hinge pins will protrude into the screen area so they require clearance cutouts from the spandex or at least some sort of staple or clip next to the hinge pin to keep the material flat to the frame in the viewing area.

Or is there no connection at all between folding sections until the straighteners are attached?
 

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I see, the holes on the drawing describe the interlocking pins between the folding section and the straightener section. So the folding section is what, hinged? That means hinges on front and rear of the frame or at least recessing the hinges but no matter how it is done some of the hinge pins will protrude into the screen area so they require clearance cutouts from the spandex or at least some sort of staple or clip next to the hinge pin to keep the material flat to the frame in the viewing area.

Or is there no connection at all between folding sections until the straighteners are attached?
There are hinges where the verticals meet the segments, but the spandex itself creates the hinge for the segment-to-segment joints. Since the actual metal hinges are only on the "inside" lip of the on-edge 1x3s there is no point where the spandex actually contacts the metal hinges. The spandex layers should have a smooth edges to wrap over top, bottom and of course outside verticals. Still, with the extra stretching the spandex would do at the hinged joints when collapsed, I had expected to need to make the screen taller so those stretched or dimpled areas around the joints could be hidden by masking panels without impinging on the image area. Also not shown is that any frame elements that will be within the image area -- the verticals in this case -- must be ripped lengthwise so they remain at least 1/4" behind the fabric. If they are in contact with the spandex, they will show through. They must also be painted black or covered in black material or they will appear as bright spots during projection.

I drew it up with six segments for two reasons. 1) it would allow for screens wider than 16:9 aspect ratio, and 2) it would leave the absolute center without a vertical so the center channel speaker wouldn't be blocked. If you aren't concerned about the thickness of a center vertical blocking a center channel, and you wanted just a 16:9 screen, then you can simplify with just four segments and a single center vertical. Likewise, if you aren't looking for the smallest bundle for transporting the screen in a small car, the straighteners can be single pieces rather than two on top and two on bottom. Of course, finding nice straight lumber is easier when none of the pieces need to be more than 6' long, so it has that advantage as well.
 

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^^^I should be able to show some pictures of this in action within the next day or two.
I'll be hinged at each joint, and find out how bad the puckers are from stretching over a 1/8" line atop (and abottom) the outer edge...if it's bad, I'll slice a relief hole, but I hope it won't come to that. I'm more worried about how the spandex will handle the more extreme stretch points, but it always seems like such tough stuff so I'm hopeful there as well.

So far it's looking like the entire thing will weigh under 15lbs at about 110" 16:9. Parts cost is around: $12-18 2" hinges, $30-45 1"X3" poplar, I think my spandex was ~$30 for both layers but likely not the best of deals, guessing under $10 for staples and dowels.

If this holds everything steady enough, I might eventually try it using 1"X2" poplar and the 1" hinges which will slightly lower the price and cut weight nearly in half. At only 110" it isn't too large and spandex is fairly low-tension. By then I'll have located the saw and drillpress...and tapemeasure.
 

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Discussion Starter · #17 ·
^^^I should be able to show some pictures of this in action within the next day or two.
I'll be hinged at each joint, and find out how bad the puckers are from stretching over a 1/8" line atop (and abottom) the outer edge...if it's bad, I'll slice a relief hole, but I hope it won't come to that. I'm more worried about how the spandex will handle the more extreme stretch points, but it always seems like such tough stuff so I'm hopeful there as well.

So far it's looking like the entire thing will weigh under 15lbs at about 110" 16:9. Parts cost is around: $12-18 2" hinges, $30-45 1"X3" poplar, I think my spandex was ~$30 for both layers but likely not the best of deals, guessing under $10 for staples and dowels.

If this holds everything steady enough, I might eventually try it using 1"X2" poplar and the 1" hinges which will slightly lower the price and cut weight nearly in half. At only 110" it isn't too large and spandex is fairly low-tension. By then I'll have located the saw and drillpress...and tapemeasure.
I am still having difficulty visualizing the connections.

The 1x3 is oriented with the 3" horizontal or vertical?

The 1x4 is oriented with the 4" horizontal or vertical?

Can you post pictures as it goes together?

Thx.
 

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Discussion Starter · #18 · (Edited)
After mulling it over some I concluded that the design you are building is too complicated, costly, heavy and expensive for my purposes, so I took the accountant's hatchet to it and came up with this proposal for an alternative light design.

Most of all I need the thing to be light and easy to build/install/remove, and dirt cheap.

When in use it will hang in front of the TV from long shelving brackets that are ceiling height. When stored it will be disassembled and stuck behind the sofa. Assembly and disassembly has to be trivial and the material has to come off completely for storage in plastic bag or machine washing.

I designed a simple 96"x54" total outline frame (110" total diagonal) made of 1x2 and 1x3 poplar, dowels, and screws. No hinges. Just eye hooks and tab-like clips will tension the screen and hold the frame together with the Spandex and a couple of diagonal black nylon cords on stick pins will square it.

The frame members consist of parallel lengths of poplar in an ell connection between the 1x3 facing the projector and the 1x2 that is attached by screws through its 1" edge and facing away from the projector. The 1x2 creates an ell around the outer edge of the frame. The boards need to be rigidly clamped square and straight before the screws are put in. Dowels are probably not accurate enough for this connection without a woodworking shop.

The top and bottom horizontal members of the frame are 8' long.

The left and right vertical members of the frame are the same construction with two differences. The 1x2 poplar of the left and right vertical members is longer to meet the 1x2 poplar of the top and bottom horizontal members.

Both the 1x2 and 1x3 portions of the left and right vertical members have dowels permanently pinned into the ends of the boards for a friction fit connection to the horizontal members.

When assembled, two vertical 3/8" dowels also connect the top and bottom horizontal members on the 1" edge of their 1x3, with the two vertical dowels at proportional spacing between the vertical frame members on left and right.

The frame is assembled with a friction fit on the dowels, and magnets are countersunk into the surface facing the projector for mask attachment. Then the frame is sprayed flat black on all surfaces.

The Spandex screen material is layered white toward projector, wrapped around toward the rear of the frame, and attached to eye hooks on the inside surface of the frame (on the 1x2) with tab-like clips. Two black nylon cords are pinned along the diagonals away from the projector, to square the frame, with additional nylon and dowel scaffolding added on the far side from the projector if necessary to flatten the image surface like a bowstring (hopefully not necessary but it might be a good idea to drill holes for the dowel anyway).

The frame is hung on j-hooks from long shelving brackets at ceiling height, the projector test pattern is focused, the nylon cords are adjusted to square the frame, and the mask is attached.

The mask is constructed of black spandex socks, with large black washers or metal disks inside them to contact the magnets at regular spacing.

Usable area: up to 107" diagonal depending on the mask and accuracy of construction. Relatively light as a feather and simple to assemble. Hopefully straight.

If the thing has to break down, the top and bottom can be cut at different lengths for the 1x3 and 1x2, and the dowels in the separated span used to lock the sections together with friction fit instead of screws.

What do you think?

Edit: swapping the 1x2 and 1x3 might keep the image flatter.
 

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After mulling it over some I concluded that the design you are building is too complicated, costly, heavy and expensive for my purposes, so I took the accountant's hatchet to it and came up with this proposal for an alternative light design.

Most of all I need the thing to be light and easy to build/install/remove, and dirt cheap.

When in use it will hang in front of the TV from long shelving brackets that are ceiling height. When stored it will be disassembled and stuck behind the sofa. Assembly and disassembly has to be trivial and the material has to come off completely for storage in plastic bag or machine washing.

I designed a simple 96"x54" total outline frame (110" total diagonal) made of 1x2 and 1x3 poplar, dowels, and screws. No hinges. Just eye hooks and tab-like clips will tension the screen and hold the frame together with the Spandex and a couple of diagonal black nylon cords on stick pins will square it.

The frame members consist of parallel lengths of poplar in an ell connection between the 1x3 facing the projector and the 1x2 that is attached by screws through its 1" edge and facing away from the projector. The 1x2 creates an ell around the outer edge of the frame. The boards need to be rigidly clamped square and straight before the screws are put in. Dowels are probably not accurate enough for this connection without a woodworking shop.

The top and bottom horizontal members of the frame are 8' long.

The left and right vertical members of the frame are the same construction with two differences. The 1x2 poplar of the left and right vertical members is longer to meet the 1x2 poplar of the top and bottom horizontal members.

Both the 1x2 and 1x3 portions of the left and right vertical members have dowels permanently pinned into the ends of the boards for a friction fit connection to the horizontal members.

When assembled, two vertical 3/8" dowels also connect the top and bottom horizontal members on the 1" edge of their 1x3, with the two vertical dowels at proportional spacing between the vertical frame members on left and right.

The frame is assembled with a friction fit on the dowels, and magnets are countersunk into the surface facing the projector for mask attachment. Then the frame is sprayed flat black on all surfaces.

The Spandex screen material is layered white toward projector, wrapped around toward the rear of the frame, and attached to eye hooks on the inside surface of the frame (on the 1x2) with tab-like clips. Two black nylon cords are pinned along the diagonals away from the projector, to square the frame, with additional nylon and dowel scaffolding added on the far side from the projector if necessary to flatten the image surface like a bowstring (hopefully not necessary but it might be a good idea to drill holes for the dowel anyway).

The frame is hung on j-hooks from long shelving brackets at ceiling height, the projector test pattern is focused, the nylon cords are adjusted to square the frame, and the mask is attached.

The mask is constructed of black spandex socks, with large black washers or metal disks inside them to contact the magnets at regular spacing.

Usable area: up to 107" diagonal depending on the mask and accuracy of construction. Relatively light as a feather and simple to assemble. Hopefully straight.

If the thing has to break down, the top and bottom can be cut at different lengths for the 1x3 and 1x2, and the dowels in the separated span used to lock the sections together with friction fit instead of screws.

What do you think?

Edit: swapping the 1x2 and 1x3 might keep the image flatter.
That doesn't seem cheap and simple to me. What you describe will cost more and be much more work than my collapsible design. It will likely take 20 minutes to assemble each time you want to use it. Will you be using a sewing machine to attach all these tabs and hooks to the spandex ? A tab every few inches around the periphery of two layers of spandex is a hundreds of tabs to sew and hundreds of points to attach during assembly. You have 300 inches of periphery for each layer of spandex, remember. I guess some of us have wood working tools but no sewing machines.:D

In answer to your earlier question about 1x3s, they are "on edge", perpendicular to the screen surface. The 1x4s are flat to the screen surface and form L shapes with the top and bottom 1x3s while gusseting the corners to hold the whole frame square. The dowels and holes were to make it easy to assemble without tools, but long wood screws in pilot holes could be left in the 1x4s so their points didn't extend through until they were tightened into place in their matching holes on the 1x3s -- as long as a cordless screwdriver was handy it wouldn't take long and would obviate the need for precision in drilling the holes for the dowels. The entire collapsed screen would fit in a bag 10x10x60. The spandex being simply stapled to the frame, it would not be washable without removing all the staples, but being in the collapsed state while cooking would protect the spandex so it would hopefully not need washing. Of course, the spandex could be attached using screen-tite strips on each segment, which would make it easily removable, but that would add about $30 to the cost compared to staples.

Be sure to come back with photos to show off your design when it's done. I'm not sure just how many people really need what is essentially a portable screen, but threads pop up pretty regularly.
 

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Expect delays. :p

I haven't gotten the dowels yet, so there's still that and the stapling, but I'll post what it looks like so far.
This was done with a handsaw, screw-driver and a cordless drill that basically only makes holes..so nothing is super straight and I made a mistake initially that'll prevent this screen from folding completely tight unless I want to basically start over (which is why I suggest following the drawing where the tops/bottoms are inside rather than above/below the sides).

 

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