Making Project: The LED Cube!

Way back in August 2014, I ordered myself a kit to build a Blue 8x8x8 LED Cube.  I had done some electronics projects before, and was feeling pretty confident about my soldering skills, so I thought I'd try to take on a tougher challenge.

The CUBE!

The kit arrived a week later, and described itself as follows:

Difficulty: Intermediate
Time: 10+ hours

I unloaded the contents, counted out the 530 LEDs, 100 resistors, and all the little bags of capacitors and ICs, and then started reading the instructions.  Apparently the first thing that I needed to do was build a jig to help keep the spacing consistent between each row of LEDs.  I found an old piece of scrap wood, marked out the 64 holes that I needed to drill, and then used a drill press to drill the holes as precisely as possible.

A jig

The next step was to bend the cathode leg of every single LED (technically, I only needed 512 of them) at a right angle.  I then placed 64 LEDs upside-down in my jig, lined up in rows, so that the cathode leg of one LED overlapped that of its neighbor.  After soldering each of the overlapping sections together, I had 8 separate rows of 8 LEDs.  I then took 3 pieces of uninsulated wire, and soldered them across the rows to hold all of the rows together in one big 8x8 LED square.
Total solder count: 80 solders

Layers and layers and layers

I then repeated this same process 7 more times, so that I had 8 separate LED squares.  So far, the project was fairly time-consuming, but not particularly difficult.
Total solder count: 560 solders

The next step was to stack the 8x8 squares on top of each other to form layers.  This was accomplished by placing one layer in the jig, and then setting the next layer on top of a spacer of some kind.  I started out using some wooden dowels, but I found that they were difficult to work with, so I switched to using 6 AAA batteries instead.

Some dowels that did not work.

In order to connect the two layers together, each of the 64 anode legs needed to be bent slightly at the tip, and then that tip needed to be soldered to the anode leg of the LED above it (in the next layer).  I found this to be extremely frustrating.  Nothing lined up like I wanted it to.  Nothing stayed in place where it wanted it to stay.  Even more troubling though was the knowledge that all of the small mistakes that I make in each layer will add up to a very non-uniform goofy-shaped cube by the time I got all of the layers stacked.  Eventually I finished puting the first two layers together.

Total solder count: 624 solders

And then I stopped working on the LED cube for a long time. And then I added another layer.  And then I stopped working on it for a long time. Not only did I not enjoy this part of the project, but I also found that it was giving me a bit of anxiety.    After many stops and starts, and lots of downtime in between, I finally finished putting all 8 layers together.
Total solder count: 1,088 solders

A completed cube!  I thought it would never happen!

After the long and painful journey of putting the cube together, I found that the next step was relatively quick and pain-free.  In fact, I rather enjoy soldering components onto PCBs, even when there are a lot of parts to solder.  Unfortunately, as I neared the end of this step, I discovered that 10 holes in my printed circuit board had somehow been printed too small!  I couldn't fit the resistor leads through them!!! I tried poking larger holes using a small pin, but it didn't work.

I wasn't really sure what to do, because if I put too much pressure on the holes, I could damage the metal rings around the holes, and essentially ruin the entire project.  After doing a little research, I discovered that this isn't a terribly uncommon problem with PCBs, and that the best thing to do is to drill the holes out with very tiny drill bits.  I purchased a Micro Drill Bit Set and a Pin Vise.  The drill bit that I ended up using was absurdly small, but it worked great, and I was able to finish soldering the PCB.
Total solder count: Too many!  I lost count!

So many components!

I was getting close to the end, but I needed to find an enclosure to put my project in.  Technically this isn't necessary, but I thought it would look better and keep it safer and free of dust and debris.  My first thought was to find some kind of glass dome-topped display case that would protect the entire cube, but I wasn't able to find the size that I wanted (not to mention that the domes I found were fairly cost-prohibitive).

A glass dome.  Too expensive!

My next thought was to use a completely transparent display case, which would enclose the PCBs and Arduino, but leave the actual LED cube exposed on top. Unforunately, even after going to a store that specializes in acrylic display cases, I couldn't find anything that would suit my purposes.

A display case.  Wrong size!

In the end, I found a pretty snazzy waterproof project case with a transparent top.

A waterproof project case.  Just right!

Once the case arrived, my first step was to knock two holes in the side for the USB port and power port.  It's things like this that usually leave me frustrated and ready to abandon projects, but as luck would have it, one of my friends had a Dremel that they let me borrow, and it did a great job of punching holes through the plastic without cracking anything.  THEN, I remembered that I had purchased a 10-piece file set a while ago, which included a small triangular-shaped file which was perfect for filing down the holes into perfect port-shaped rectangles!  

Nice port holes!

Then, I built a plexiglass platform for the Arduino to sit on.  I really needed some non-conductive spacers, but I couldn't find what I was looking for at my local hardware store, so I just built my own out of small pieces of plexiglass by drilling a hole in them, and sanding them until the looked like little clear plastic washers.  

An Arduino sittin on some plexiglass

When I put the PCB on top of the Arduino, I discovered that it didn't quite fit because one component (a power port on the PCB) butted up against the inner corner of the casing. This stumped me for a while, until I realized that I don't actually need that power port (ever), since the whole project can be powered through the Arduino (which I had already drilled the port hole for).  I ended up sanding down the corner of the PCB power port until it fit in place.  It looks a little strange, but it doesn't affect the function of the cube in the slightest.

After that, I needed to drill 72 very small holes in the lid of the case.  I started out using the pin vise, but it took a very long time and I broke my drill bit after only two holes.  Frustrated with hand-drilling, I experimented to see if the Dremel could handle my tiny drill bits, and sure enough, it could!  Using the Dremel, I got all the holes drilled in no time at all.  

So many wires.  So many holes.

At this point, I realized that the legs of my LED cube weren't actually long enough to reach the PCB through the lid, so I soldered 64 additional 2" extendo-legs onto the bottom of my cube. Then, I fit all 64 legs through the holes in the lid (which was much more difficult than you might imagine).  And THEN, I had to fit all 64 of those legs through some holes in the PCB, which was even more difficult.  Especially since not all of my legs were the same length.  I ended up using needle-nose pliers, and doing a lot of wire bending.  Once the legs were through, I soldered the legs to the PCB.  

Almost done!

I still needed to add eight additional wires (one to each layer of the cube), and the instructions said to use bare wire, but after testing one out, I found that I was probably going to have some issues with these wires bumping into other wires and create a short circuit, so I decided to use black insulated wire instead.  It looks a little strange, but I figured that it was better to be safe than sorry.  Once I soldered those final eight wires into place, I fit the PCBs together with the Arduino, and then plugged it in to the wall...

It's beautiful!  But does it work?

A few lights lit up on top!  I had no idea what that meant, although it clearly meant that it was at least somewhat functional.  I then unplugged the cube, connected it to my laptop using a USB cable, and uploaded some sample code to the Arduino.  I was prepared for something to go very wrong (nothing happens at all / some of the LEDs are burnt out / large explosion), but much to my surprise and happiness, everything worked great!  As soon as I ran the new code, the LED cube burst to life, and cycled through a number of cool displays.  Hooray!!!  The LED cube works!!!  

Difficulty: Yes

Total Time: 30 hours?  3 years?  A long time!!!

Total Cost: $170 (plus $25 for the micro drill set)