It's a work in progress, and is being updated as I complete the work on my 8x8x8 cube, and find time to do updates.
THIS JUST IN: if you FUBAR anything based on what I write or don't write in this instructable, it's all your own fault.
Step 1: Components
I've taken screenshots from e-bay to make it easier for you to find the components needed for the 8x8x8 LED Cube build. I didn't bother with the capacitors, since they mostly look all the same, and as long as you get the right Fahrad and Volt rating, you'll be good.
Step 2: The Template
I use 5mm LEDs, and drilled 5mm holes that I reamed with a screwdriver that happened to fit really well. I enlarged the holes so that the LEDs fit snugly, but are still easy to extract once the whole layer is complete.
Notice how in the first row all the cathode legs point to the right. In the other rows, all the cathode legs point to the top/straight ahead. In the picture below I was still in the process of figuring this out. In the end you end up with a structure that looks like a comb, like Chr said. That's why you need the bracers - to strenghten the structure
Step 3: Test Cube - Learning by Doing
I must admit that at first I could not properly envision how the layout of the LEDs would be. I tried reading Chr's instructions several times, but I was still confused. After trying it out for myself, all became clear :D Learning by doing is a powerful technique, if you can call it that.
Lesson: Bending the LEDs
hold the LED with the notch/flat side pointing to your right, and fold the shorter leg straight forward. The shorter leg is the cathode (negative).
After having built the first two layers, I wanted to stack them on top of each other. Suddenly I realized that I had not bent the longer anode (positive) leg to get around the bulb of the LED above it. It was a little pain to bent the legs after having soldered the first layers. If the soldering is not solid, they might break from the strain of you bending the anode leg.
I'm going to start bending the anode legs at the same time I bend the cathode leg. You'll have to experiment a bit to fint the right angle and lenght for the bend in your own project. I think I need to bend the anode 5 - 6 mm from the top in order to clear the bulb of the LED above.
The finished 4x4x4 cube is somewhat crooked because of this, but the good news is YOU can avoid this. Besides, it's a test cube.
Step 4: Soldering
Also remember to test each LED after you've soldered them together. Easier to remove a bad one now, then when the cube is finished. Check all LEDs in each layer.
Step 5: The Latch-board
Any how.. the brains. I started out by hunting down my 9x15 cm predrilled, copper eyed boards. Thank you China! You better make sure you're not using a board that has continuous lines of copper eyes, but one that has all the eyes separated.
I placed the components like I saw in Chr's instructable, but noticed that they seemed a little cramped. I figured out that offsetting the components by one line at the top and left side wouldn't do any harm, and would give me a little more room to work with. I also allowed for one line more in between the rows of components. I happily started soldering, only later realizing that I had left myself little space for the 74HC138p-chip and the 20-pin connector. I think it'll be alright, but time will show. I'll update later on this point.
Here's the picture of what Chr's board looks like.
After looking closely, I actually noticed that you NEED a line free at the top for placing a capacitor later on.
Step 6: The Latch Board - Bottoms Up!
Step 7: Latch Board Backside 2
When soldering the long continuous bridges, remember to rinse off the the tip of your iron from time to time. Soon enough the solder will start to stick to the tip, and you'll pull the solder from one eye to the next, leaving the first one short on solder. Take your time, and buy plenty of solder :D
When you are done, it's wise to use your voltmeter to check that all connections are solid, and that you haven't inadvertently made a bridge where there shouldn't have been one. I made a few wrong connections, and had to use a solder lace to undo my mistakes. Note to self: don't work in poor lighting conditions late at night.
Step 8: Latch Board Backside 3
Step 9: A Note on the Kynar Wire
I cut the wires to desired length and straighten the pieces a little, before laying them on a flat, smooth surface and gently roll them a few revolutions with the exacto blade. You don't need to use any force at all. Just gently resting the blade atop the wire and rolling it will be enough. You don't need to cut all the way through the jacket in order to be able to remove it with your nails. If you use too much force, the wire will likely break when heated by the solder.
Also you don't need to remove a lot of the jacket. Between 1 to 2 millimeter depending on your soldering skill and eyesight.
For the shorter wires I ended up with a wire length of [have to check this to be sure :]
The longer wires I cut to 6,5 cm, but I think they were a little on the long side. You can probably cut them to 6,0 cm or shorter and still be comfortable.
Step 10: Latch Board Backside 4
If you look closely at this (large) picture of Chr's board, you can see that they started doing this only at the bottom row.
Step 11: Latch Board Backside 5
As always check connections from first to last point with a voltmeter.
Step 12: Latchboard Backside - Caps and Bridges
I did not plan ahead like that and had to remove the solder from two eyes, place the bridge and resolder. Didn't take too much time, but still would have been easier to just place them while soldering the rails.
Next up were the capacitors. Like Chr said - use them like candy. I just follow Chr's instructable as closely as I can, candy or no candy.