LED or Acrylic Frame Idea - raiding the window and door department
Posted: 20 March 2009 12:41 AM   [ Ignore ]
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I am reposting this from another thread, since it is a sizable reply that probably merits its own discussion, and that I will update with my results - I figured thread hijacking probably isn’t too polite smile Original thread at http://nuigroup.com/forums/viewthread/4706/

I was recently in “Menards”, a US (midwest?) home supply store/construction store/basically something kind of like Home Depot looking for useful multi-touch parts, when I stumbled across a potentially great find.  In the window section, they had eight-foot long strips of vinyl (stiff plastic) labeled “drywall receptor” that was more or less in a lower case h-shape (apparently used for installing vinyl-frame windows).  They stocked a variety of widths, and each 72” (six-foot) segment was around four dollars, except for one, which was eight dollars.  (US dollars).  I seem to also recall seeing a similar shape, though not quite the same thing (more of an _|- shape if you can imagine that hypen at the top instead of in the middle - do I call that an S shape?), in steel for about the same price on an earlier trip, though it wasn’t in that section, and I couldn’t find it again in the limited time I had to browse.

Also, in what I believe was the door section, although my notes say it was a different window section, I found a similar item, but in a the wider variety of shapes, all 8 feet long, and all around three dollars or less.

Some of these items had a fairly deep channel, and certainly deeper than the aluminum U-channel they also stock.

I had a couple application ideas for these items.  They could be used to mount an acrylic sheet, with or without a strip of LEDs on the edge.  I think they might also work in an LED-LP system to make the infrared frame, and also perhaps an LLP if lined with an absorptive material for the laser.  While I don’t think I’ll be able to test the LLP system, I anticipate trying them in an LED LP system and will share my results on the forum.

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Posted: 20 March 2009 01:01 AM   [ Ignore ]   [ # 1 ]
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This is great stuff...I need a frame for my LEDs and not a single hardware store close to me has the kind of materials needed for this. Actually, one home depot guy told me to go look for bi-fold door materials...sounds like what you found. I’m looking at the menards website right now...hope I can find it! any chance you could post a SKU or something like that? website’s not doing it for me...thanks!
~rbedi100

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Posted: 20 March 2009 09:34 AM   [ Ignore ]   [ # 2 ]
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Great find.

Yeah, I’m still a little cranky about my process. Someone had suggested that I look for window framing materials. But none of the hardware stores nearby carry it. They all have screen framing materials, but those won’t accept something 1/2” or so thick. I had found a store about 45 minute drive away that I was going to go to this weekend. A friend of a friend was going to help me with that if I found it. Evidently there are special fasteners that are used to hold it together, but I haven’t seen what they are. Have you figured out how you are going to hold it together?

Also, I don’t know about aluminum vs. vinyl. If they carried both I would probably go with aluminum. How well does vinyl absorb/dissipate heat?

But I’ve decided to give aluminum “L” a chance.

I got 4 pieces at at about $5.00 each, cut them with a hacksaw and a guy from work is going to weld them for me. I’m still not exactly certain how I’m going to frame/cover the top. And if I do find the magic aluminum window framing....

One step at a time.

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Posted: 27 May 2009 05:24 PM   [ Ignore ]   [ # 3 ]
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Update: I indeed used these cheap plastic bits for mounting my acrylic for my rear-DI setup, and I’m using a larger similar product (called “j-channel” used for vinyl windows) along with a black closed-cell foam for my LLP light blocking edge and acrylic support.  More photos of the rear DI system with the rails in close up can be seen here: http://compsci.snc.edu/cs460/pavlra/hardware/desk1/

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There’s enough room that if you were using a projection/diffusion surface that wasn’t too stretchy, you could wrap it around the edge of the acrylic before putting it in the railing to hold it on tight.  I was using a thinner, slightly stretchy shower curtain and I wanted to be able to change it out easily, so I applied double-sided tape to the top of the rail, put the diffuser over, and cut it to fit.  Works nice!

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Also used it to hold my mirror to the backing board - I actually hinged mine.

18.jpg

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Posted: 28 May 2009 09:07 PM   [ Ignore ]   [ # 4 ]
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Have you thought of Using FRP (Fiberglass Reinforced Plastic) for the inside of the box? It’s the material that you may find in a public restroom, but most common in industrial complex restrooms. It’s a very durable and sturdy material that you can use a sawzall or battery powered Dewalt saw to cut it with.
Also you can get trim pieces for it that will connect two pieces together at the seams or in the corners. One side of the material is corrugated of ruff surfaced while the other is perfectly smooth. and will stick to the inside of your setup with Liquid nails or PLR adhesive. This is what I think I’ll use hence the recommendation. And are those IR nighttime surveillance cameras that you are using kind sir?

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Posted: 28 May 2009 09:25 PM   [ Ignore ]   [ # 5 ]
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Interesting, no, never heard of it but I got an old overhead projector screen free so I figured I’d use it smile It actually worked great - cut nicely, screwed into the underlying desk pieces easily (just with cheap woodscrews at the top, and doublesided tape in places at the bottom to keep it flatter), and was flexible enough to let me route cables, etc. behind it, not to mention the inside corners where I used one continuous piece (3 of the 4 sides) were smooth though I don’t think this matters so much.  This desk works really quite nice now - I should post a showcase thread about it.

Those are the standard 48 IR LED illuminators people tend to get from ebay - I got mine off DealExtreme and were a little cheaper, though shipping was slow (can’t compare to ebay, though, since I only bought one set - ebay might be just as slow, since they all apparently come direct from hong kong).  They ended up being about $15 a piece, I think - they’re here: http://www.dealextreme.com/details.dx/sku.15235

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Posted: 28 May 2009 09:42 PM   [ Ignore ]   [ # 6 ]
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Thanks for the Link! Some one else was inquiring about the LED’s in the beginners thread under “community” I think. I’m planning an RDI setup as well and this is why I suggested the FRP. Any thoughts on the difficulty of building my own projector? If looked at Instuctibles.com for ideas and those where rather unhelpful in the matter. I think I might use an overhead projector (dismantled and rebuiltfor this application), but have it set in a separate compartment. Also, I think you chose wisely in the aluminum trim piece. I think the vinyl would have retained to much heat.

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Posted: 28 May 2009 10:50 PM   [ Ignore ]   [ # 7 ]
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No, somebody else did aluminum (look at who posted - not me :/) - I did the vinyl, and I’m not sure why it would retain heat: the heat is being generated at the projector, and a little at the illuminators, neither of which are close to the rails.  Most people don’t rely on heat to be conducted out (metal components) but rather ventilate somehow: most use fans, I actually have my projector on a drawer that slides out for use so it’s not enclosed.  I have had no heat problems - the vinyl doesn’t get warm because it’s not near anything actually producing heat.  This application is complete and the vinyl works great, really ideal!  Unless the aluminum was being used as structural (creating a screen in air, rather than putting on a desk or table), I don’t see any reason why you’d want to use something else with a rear DI setup, and I bet you could put the LED strips in either this narrow stuff or the wide J-channel for FTIR and DSI.

Those build-your-own projector things always looked a little sketchy to me - I used an old one computer projector (really old - like mid 90’s, worth about $40 on ebay) given to me for basic setup/testing, then checked out a nice one from the university when I wanted to do demos or presentations - the department is buying one of the benq short throw projectors (something like 512-st, IIRC - I did not check, just a guess).  You could certainly try it, but I’d suggest leaving that until last, since most of the process can be done without a projector: the only thing you need a projector for is if you actually want to touch images on screen: you can even “calibrate” by laying out a little grid on your surface to use in the ccv calibration (just did that today on my LLP with my visible lasers before I do the big switch to IR and enabling on the LCD) and use MT apps.

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Posted: 29 May 2009 12:15 PM   [ Ignore ]   [ # 8 ]
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I did not know that! I think I will wait on the projector part then. This was part of my biggest set back on my build. And I must have been thinking of another project when I thought about the heat retention of the trim pieces you chose. I may have been thinking of making cookies as well!  cheese  Thanks for posting, I hope to start the table build this week!

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Posted: 06 June 2011 04:37 AM   [ Ignore ]   [ # 9 ]
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hello, everybody very likely does not be sure or about me, but I retain you ... 
I’m with you and I fancy that things being what they are go through a official family. So paralysed a progress it all later to petition and demand what next ... 
regards

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