Introduction: Cube Aid

About: Interested in retro clocks and time itself

I have liked 3D cubes for ages, fascinated watching the various patterns and have built a couple. They always involve quite a bit of soldering, especially if they are of the 8x8x8 variety but I recently took on another instructable which is 8x24x8, that's 1536 LEDs.

If you want to see what I am building, or by the time you read this may have built, see the Instructable 8x24x8 RED GREEN BLUE LED CUBE
By tuenhidiy in Circuits, Arduino. I am really grateful to the author of the 8x24x8 cube for the help he has given me to understand his design.

It was this project that set me thinking.

Just to make it clear. This Instructable is not about a cube, it is a construction aid to make a cube.


PCB design software, in my case DesignSpark PCB.

Computer running Windows 7 (or later),, 32 or 64 bit if using Designspark PCB.

Step 1: Requirement of All 3D Cubes

One of the problems in constructing the LED matrix is aligning the LEDs and maintaining the stability of the finished cube so I looked to see if I could improve things and make my life easier.

Constructing the matrix involves aligning the LEDs and supporting them for soldering. The usual solution is to construct a jig, a wooden baseboard with 5mm or 3mm holes drilled according to what size LED you are using. These holes have to be accurate. The resulting panel of LEDs are then either soldered to a perf board or a designed PCB. A 8x8x8 cube would be constructed of 8 panels, each panel consulting of 64 LEDs arranged in an 8x8 square. In the case of a PCB being used once again 64 holes have to be accurately drilled only this time smaller, to take the LED legs.

Step 2: My Build

The instructable involved makeing the PCBs at home, however I no longer have the facilities to make my own boards so choose my usual route of designing them and getting them from JLCPCB.

The software I use is Designspark PCB It's free and not restricted in any way and quite comprehensive although this board is simplicity itself.

The PCB was designed with solder pads placed at 27mm centres with 8 x 8way connectors suitably positioned and thus 64 connections for the cathodes (or anodes) and an 8way connector for the anodes (or cathodes). I actually made the board symmetrical so the single 8way connector was duplicated on the opposite side of the board.

Each PCB is an 8x8x8 cube, 3 of these are constructed to make the 8x24x8. The minimum order quantity for PCBs from JLCPCB is 5 so not too wasteful.

Step 3: Lightbulb Moment

While designing the board to take the LEDs I realised that I had laid out the positions of the LEDs to be soldered on the board so copied all 64 locations and shifted then about 1 cm to the left. I then changed the hole size to 5.1mm with a pad size of 3mm. This resulted in a plain hole. I then designated them as non through hole plated and when producing the Gerber files produced 2 drill files, one plated through, one non plated through as the PCB manufacturers wanted. I also specified the boards to have a black solder mask. The picture above shows the design on the computer. The black background has nothing to do with the solder mask colour, it's just how I have set up the display options on the software.

The beauty of this is the holes are an exact positional copy of the solder holes and also I do not have to accurately drill the 64 holes in a piece of wood. That work is done by the PCB fabricator and the circuit board became dual function. Firstly to help construct the 8 layers and then be the base of the cube.

In my case, as the LEDs are 27mm apart, they are connected together with 18swg tinned copper wire. Suport and connection to the layers is provided by 16swg copper wire, in this case not tinned.

As I did not want to have the construction aid holes showing in the finished product I covered them with small 5mm plugs you can purchase to cover screws in kitchen furniture.

Step 4: Construction

It's always satisfying to receive the boards. Not forgetting the obligatory sachet of silica gel and the free gift, this time a key ring in the shape of a hamburger.

The final photograph shows matrix under construction on the board which will become the base for the cube.

Step 5: Just to Point Out

Although these boards are for the 8x24x8 cube, cubes usually use the same matrix idea so the boards are good for most 8x8x8 cubes if you want the LEDs at 27mm centres. Now that the proof of concept has been finished, the design can easily be changed for 3mm LEDs and/or different spacing.

Step 6: Clarity

I would just like to clarify that I have no connection with and have not been payed by the providers of Designspark PCB or JLCPCB. Nor have I received any free or reduced price boards from JLCPCB. I just mention them for completeness. Other software and PCB fabrication companies are available.

As an aside I also designed PCBs for the rest of the electronics.