OK, I've test-mounted 100 x 12mm RGB LED pixels on a sheet of cardboard.

(Jason Coon) #1

OK, I’ve test-mounted 100 x 12mm RGB LED pixels on a sheet of cardboard. I definitely like it so far. Questions:

Anybody have experience mounting these? Do you prefer ABS, acrylic, metal, or something else? 1.5mm or 1/16", right?

Advice on the best layout, for when I later try to map to XY and/or polar coordinates? I ran these in a spiral, from outside to inside, but I’m wondering if zig-zag, or radial from inside out on each spiral arm would be better.

More info, photos & video: https://goo.gl/photos/PKdywS4g8Ngv1umD8

(JP Roy) #2

Good start !
My experience is with the 8mm LEDs. The ones you use here have some form of clear plastic jacket on them. I guess they are meant to be pushed-in so they lock in place !? That should give you an indication of the material thickness needed.
As for the material itself, I guess it all depends if you intend to ultimately cover it with some type of diffuser and/or nice case around it. If so, just go for cheap MDF that you can just paint black or whatever.
As for the layout, I guess you mean from an electrical or interconnection point of view, it seems to me that a radial from inside out on each spiral arm would be better but you will probably be stuck with doing some mapping to XY co-ordinates anyway for some animations !
Have fun come back with your results !

(Andrew Tuline) #3

Would be interesting to know about the mounting material. Think I’ll head to Home Depot today.

(Jason Coon) #4


These are the ones I ordered, they’re $39.80 for 100, with free shipping: http://www.aliexpress.com/item/12mm-100-node-lot-DC-5V-waterproof-IP68-Full-Color-addressable-WS2801-RGB-RGB-Pixel-Module/32322649250.html

They seem similar to the ones Adafruit carries: https://www.adafruit.com/product/322

They’re 8mm LEDs, sealed in a silicone sleeve. They say: “There are four flanges molded in so that you can ‘push’ them into a 12mm drill hole in any material up to 1.5mm/0.06” thick."

I’m debating (and plan to test) what would be best/sturdiest: acrylic, ABS, HDPE, etc. I wondered if I could save some time by asking the resident experts. :slight_smile:

I’m not sure whether I’ll add a frosted acrylic sheet for diffusion. That’s another thing I plan to test. But it’d be nice if it was finished and clean so that it could be used either way.

Yeah, regarding layout, they’re pre-wired, with connectors every 50 pixels, so whatever pattern I use, it’ll likely need to spiral or zig-zag in some manner. I’d prefer not to cut and rewire to run each spiral arm from the inside.

Thanks again, I definitely plan to post more pics, video and details along the way.

(Marc Miller) #5

I would think mapping will be needed no matter how you wire it, so then wire in whatever way makes it easy. I probably would have initially tried a serpentine-ish wiring, but spiral might be better. Spiral also has the added bonus that it seems to work immediately with something like Mark’s Pride2015 code. That already looks cool.

(JP Roy) #6

@Jason_Coon Blank PCB material would probably be sturdy enough, the right thickness, cheap but not pretty unless you paint it !
Ahh… yes… they are pre-wired so some layouts may not be practical. That’s ok just means you will have to map the physical layout to the actual pixel position in the string.

(Jason Coon) #7

Thanks again, guys. Yeah, I’m not too worried (perhaps naively) about XY mapping, but polar mapping seems like it won’t be easy, regardless of layout. I assume polar would be the way to go, for making each spiral arm addressable, but maybe not. I’ll start brushing up on my trig and calc. :slight_smile:

PCB material is a good idea, thanks! I’ll add that to the list of test materials.

(Jason Coon) #8

Oh, and I’ll preemptively point out that while transferring the printed pattern from paper to cardboard, I missed four of them. I didn’t notice until I had spare LEDs left over. I’ll make sure to correct that in the final material. :slight_smile:

(Juergen Bruegl) #9

I’d take a rubber ball and cut it in half - that gives you the third dimension

and a flexible adhesive

For the holes use a normal drill from the inside

(Ken White) #10

You might want to try using Polyiso Rigid Foam Insulation Board (1/2 in. x 4 ft. x 8 ft., Store SKU # 754404) from Home Depot. It is inexpensive and will hold your 12mm RGB LED pixels in place. I know because I tried it with similar RGB LED pixels. See :

When I did this, I tried using a lab cork borer to make the holes but this ripped some of the foil on the board. A hand drill worked better.

(Jason Coon) #11

Talked to a guy at a local acrylic shop, and he recommended against 1/16" acrylic, at least at the size I’m talking about. There’s not a lot of space between the holes, and he said it’d likely crack.

(Andrew Tuline) #12

I went out and bought a 2’x2’ sheet of 1/8" hardboard today. About $2.

(Jason Coon) #13

@Andrew_Tuline , I assume you have some of these LEDs? If so, will they snap in to 1/8" material? I plan to try this out tonight, just wondering if you’d already tried. Thanks!

(Jason Coon) #14

Hey @Ken_White , for some reason your comment got marked as spam. I marked it as safe. I’ll add Polyiso to my list of materials to try, thanks!

(Andrew Tuline) #15

OK, tried it out. Used a 7/16" drill (wish I had a metric set). Had to wiggle the drill somewhat to get it large enough. Drilled test holes for a couple of LED’s. Although they didn’t ‘snap’, they did fit snugly and I figure any that end up getting loose will be getting the hot glue treatment. I’m good to go with this.

(Jason Coon) #16

Yeah, I couldn’t find a metric drill bit set, but I did find one with 15/32" and 31/64" (imperial units are silly).

I tried a small sheet of 1/16" acrylic, but cracked it while drilling the first pilot hole with the smallest bit I had.

I picked up a 10" extra-deep shadow box and some 1/8" hardboard. I just finished drilling and sanding 100 holes, and put on a few coats of black spray paint. Now just waiting for it to dry so I can mount the LEDs. Will report back with more pics soon. :slight_smile:

(Jim Bumgardner) #17

I used a 1/16th acrylic sheet for my fibonacci lights (although I think it would be better to use something stronger). I’m using a 1/8 acrylic diffuser in front I got from Tap plastics. My lights are 12mm punctiform, and I eyeballed the wiring order to optimize for shortest connections. I use a 1d array in my program to map to polar coordinates (inner to outer). I found a pretty good 3-inch deep 12" square frame at Michael’s to mount them in.