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-   -   How can I mask my DIY fabric screen? (http://www.avsforum.com/forum/23-screens/19548-how-can-i-mask-my-diy-fabric-screen.html)

kensilver 09-16-2000 02:21 PM

Hi all,

I've followed all the posts on this forum - particularly the long thread on screen fabric - and it has been exceptionally useful in helping me develop my current screen.

My first screen was a half-inch thick chipboard sheet about 6' x 4', painted flat white, and edged with a few inches of black velvet. It was an improvement over my off-white colored wall, but the overall effect was messy... the glue seeped through the velvet mask and reflected as bright spots, the chipboard wasn't smooth enough and I saw the texture whenever there was a panning scene.

For my perfectionist trait, this was a disaster.

So I revisited the stretcher bars and blackout fabric thread, and decided to do this.

It was amazingly easy. Instead of sweating for 2 days over sanding, painting, cutting and gluing as I did with my old screen, this one was completed in an hour.

I bought stretcher bars from the local art shop, 66" and 44" - two of each. They fitted together nicely, and I decided not to glue them, figuring the fabric would hold them together and keep them square too.

The blackout material was a very slight off-white, maybe 5% if it could be measured. I stapled this to the bars, starting at the middle of each bar and working my way round, a couple of staples at a time. In 20 minutes I had a perfectly stretched screen with not a wrinkle in sight. This was VERY encouraging.

I had black velvet left over from my first screen, so I ironed a sharp fold in the strips to give a clean edge, and stapled the two vertical strips top and bottom, then along the sides to give a neat side-on fit.

The top horizontal strip was just stapled at the top and I let it hang over. The bottom was fixed with a couple of rubber bands secured through a hole at each end as a temporary measure.

OK - I'm getting to my masking question... but first, the test. Last night I put the screen up, and, bing - perfection! It was even better than the Da-Lite I had bought a week earlier and returned because I got markedly better performance off my wall. (Surprising - but true... there was a 50% improvement between my off-white wall and the Da-Lite).

I have an old SharpVision LCD that I had bought for a song, and replaced the bulb (the bulb was twice the cost of the projector!) The new, slightly gray screen has reduced the chicken wire effect, which I mostly focus out anyway, but the screen quality is mighty. No hotspots, it is flawless, with good blacks and whites as you can get with this primitive 220 ANSI lumen projector.

Now, my problem. The screen is masked at the sides and top and bottom in the 4:3 ratio. I want to devise some masking system for the top and bottom only to get the other ratios.

One thread on the subject suggested rare earth magnets. I can't figure out how this would work. You'd have to have the masking material on a backing board, and I haven't had much success mounting it. So this is out.

What I think I need is some tensioned roller blind arrangement where the black material is drawn down - and up from the bottom - and secured with black-painted clips. This way I can mask very closely.

Any thoughts? How are the electric masking systems on Stewarts done... will they give me some ideas?

Your ideas from this marvellous forum are appreciated!

Thanks,

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Ken Silver

kensilver 09-19-2000 10:02 PM

No ideas yet from anyone? Doesn't matter... I came across the answer while at a fabric shop a couple of days ago, and it works like a dream!

This shop sold multi-length roller blinds. They are designed in variable a telescoping style, and I selected two that were close to the width of my screen.

I rolled black light absorbing fabric on to each blind, after I had made them the correct size, and screwed in the holding brackets to my screen. These simple angled brackets were held by two screws each, and I fitted them behind the screen, top and bottom, so they were out of sight when viewed from the front.

For the screen side of the fabric I used a long length of flat plastic rod, attached double-sided cellotape both sides, and rolled the fabric on to it for a permanent fit. This made a sharp, neat line that was easy to grasp on to for drawing the blind up and down.

The top mask just comes over the top of the screen and hangs quite happily at any aspect I choose.

The bottom one was harder. I let the plastic rod extend a half inch outside the fabric and drilled a small hole at each end. These fitted over small nails hammered into the screen at the various aspect ratios, holding the fabric taut.

All together a great success! I would post photos, but you know how hard it is to photograph black light-absorbing felt... like a black cat in a coal cellar at night :-)


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Ken Silver

kensilver 09-21-2000 04:22 AM

JBM,

Thanks for your more detailed info on your magnet attachments... I can visulise it much better now and it sounds more do-able too.

One of the problems I faced with attaching any sort of board to my screen was the variation in sizing. With the three formats I have on my DVDs I would have to make at least 2 boards. The blinds concept seemed to cover every sizing problem likely.

About the bottom roller tension - that is a problem, as it sometimes doesn't stop when it should. I will have to look at ways of releasing the stop-tension so that it is always taut. Shouldn't be hard... after all, this is often the first thing to break on old blinds!


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Ken Silver

KBK 09-21-2000 07:04 AM

I have purchased some 8 foot steel 'square' galvanized 'studs' for building office walls. Then I purchased a solid bit of black felt covered black plastic material from a local fabric shop. I haven't used it yet for masking, as I am attempting to make things as difficult for myself as possible. I use an oversized screen with no masking, as if I can get great picture witout masking, it should be considerably better when I actually use masking. I use the masking every now and then for a reality check and then go back to no masking. The lack of masking allows me to deal with aspect ratio changes quite handily though. Those bloody DVD's are all different!

The bars also double as a partial shadow box, as they stick out a bit.....

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---Place Signature Here---

kensilver 09-21-2000 04:00 PM

KBK,

Those beams must make for a heavy screen? My first screen was solid chipboard/particle board, and I forgoed my daily weightlifting exercise simply by shifting that beast around. Is yours permanent?

My current beauty is light as a feather.. I can lift it with one finger. I need the lightness because of my set-up, which I'll explain: my Panasonic 29" flatscreen sits in the corner of our small square media/family room, with a Technics THX sound system flanking it... the two L and R speakers spaced wide on either side of the TV, and the middle speaker in the televison's stand underneath. The 2 subs and 2 surrounds sit in the other corners at each end of our sofa. Not perfect, but there's no other way for positioning them as windows take up a large part of the room. We sit high on a hill overlooking our harbour - I wouldn't give up that vista for anything!

To view projected DVD's, I designed the screen so that it hooks on between both the L&R speakers using simple eyescrews and hooks - 2 each side. This positions it neatly above the middle speaker too, and of course the sound is perfect.

The other advantage is that the screen completely covers the TV. So when I want to use the video projector for standard tv programs, the screen blacks out the tv which has to be switched on to change channels etc.

However, it's all a compromise until I can get a purpose-built HT. Roll on the day!

Masking is necessary for me because I have advanced anal-retentive tendencies :-) I simply cannot abide sloppy masking. My old Sharp LCD puts out a 4:3 picture standard and then provides (gray) letterboxing for widescreen DVD and other formats. So masking is a necessary evil.

I know using masking also degrades the blacks within the picture (blacks? What blacks!) but the overall effect is more theater-like this way.

An interesting aside: Earlier I started buying fullscreen DVD's for my TV's 4:3 ratio. Now, with the purchase of the projector, I needed them in 16:9. After realizing this, and with some moments of panic, I went back to my meagre collection and looked for the formats. Phew - all of them offered a 16:9 (or close 1.85) alternative. Something's going right at last!


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Ken Silver

DRS 03-21-2001 12:11 PM

Ken,

Do you have any pictures of your setup? I am interested in seeing the final product, thanks.

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System info: Native XGA LCD FP, Dalite 57X77 HP, P3 700, ATI Radeon, ATI 7.1 player, WinDVD 2.6.4, WinME

rickforrest 03-21-2001 12:21 PM

kensilver said -
"I know using masking also degrades the blacks within the picture (blacks? What blacks!) but the overall effect is more theater-like this way."


Really? Could you explain?


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