8x8x8 RGB LED Cube

Summary

These displays fascinated me when I first saw one on Youtube. I had to build my own. This is an 8x8x8 8 color (I also made a 256 color) LED cube. Each LED can be set to any color. For the final version, I had coded 3D position and rotation algorithms, so I could load in custom meshes and translate and rotate them very easily. I also created a few games on the display: 3D Pong, Snake, and even Asteroids.

Construction

Step 1. Prep

First things first, you need LEDs (Diffused ones, as I mentioned above). If you’re patient enough, I recommend getting them on ebay from some source in Hong Kong. You can get packs of 100 or 500 for a LOT cheaper than buying them bulk on Digikey or another site like that. I’m talking saving hundreds of dollars here.

Next, you’ll have to straighten out a bunch of galvanized steel wire. I chose 22 gauge wire. It’s thin enough that you can straighten it easily, and it takes solder well. It’s also strong enough to act as good frame support for the cube.

So how do you straighten of bunch of wire that came from a spool? I had to look this one up. One of the more popular techniques is to stretch each piece of wire until just before it breaks. To do this, use a “C” clamp, or whatever clamp you can find, to hold on to one end of the wire. If your clamp is mounted to your workstation, that’s good. I just chose to slide the clamp onto my door handle. Now, grab the other end of the wire with a pair of needle nose (or similar) pliers. Slowly pull/stretch the wire toward you, and you’ll start to feel the wire stretch itself out. You’ll probably break the wire your first few tries, so be sure to have extra! Each time you do it, you’ll get better at knowing how far you can stretch it without breaking it. Once it’s straight, carefully unscrew the clamp off of the other end, and place it aside. For an 8x8x8 RGB cube, you need to do this over 250 times (4*64 plus a few extras for cross beams). I quickly caught on that I could cut the wire to twice the length a side of the cube, and only need to straighten half that. Trying to straighten wire much longer than that gets very hard.

Step 2. Build a jig

Step 3. Build LED planes

Now you can begin the long and laborious process of building 8 planes of LEDs. Each plane consists of an 8×8 grid of LEDs. Take your straightened wire from before, and begin laying them down, using the Lego pips/dots as guides.

Careful when you’re clipping the excess wire, these things can move, baby!

Step 4. Align the planes

For my first version, I bought some clear plexiglass at a local hardware store. I recommend using black ABS plastic, which I used in my second version (and seen in most of my Youtube Videos like my Asteroids one). Carefully measure the distances between all of the wires on any of the LEDs. It’s easiest to measure using a bottom LED. Also measure the distance between LEDs when they’re still in the jig. You’re now ready to mark on the base plastic where you need to drill holes for the wires to go through. The more precise you are in this step (all of the steps require precision…), the better it will look in the end. Drill your holes and begin the tedious process of aligning the wires in a single plane into the holes in the base. It’ll help to tilt the plane to one side and work your way down from one end to another.

Now you’ll need to connect all the planes together. I borrowed a long Technic piece from my jig so that the planes were equally spaced apart. Starting at the top, solder a wire perpendicular to each of the planes, the full length of the side of a cube. This wire connects each of the planes’ row to the corresponding row of the other 7 planes.

Step 5. Getting signals to the LEDs

I figured I’d want the capability to easily remove the controller circuit from the cube, and so I didn’t want to hard-wire the signal cables directly to the controller. Instead, I chose to put headers on the controller board, and make custom connectors that plug into those.

The Finished Product

Schematic

PCB