An experiment with CNC milling PCBs turned into a window display piece with lights and motion. Click through for more pictures and some details.
Circuit board milling on a Roland iModela is relatively straightforward (mainly thanks to tutorials such as Mario Lukas’ (in German, but Google Translate does a good enough job)). After a few tentative experiments I was able to make single-sided boards and using isolation milling (only taking a single pass to isolate traces or areas of the board) a relatively small board could be completed in 8-14 hours (I wasn’t pushing the speed of milling through the boards but this could likely be improved). I selected 1.8mm Copper Clad FR2 as it is constructed of epoxy/paper rather than fibreglass which is far easier on the tools (blunted a few saw blades on fibreglass PCBs). Although I had got the hang of Eagle and PCB-GCode (as described in the linked tutorial above) I went for a workflow which involved AutoCAD and dxf2gcode together with some hand-written gcode (for the drilling). CNC Simulator Pro allowed me to check my gcode was good before I took it across to the iModela.
I wanted something to display at MAKLab to advertise that PCB milling was a nice quick and easy way to prototype circuits but a plain board wasn’t going to cut it, it needed to be eye catching and hopefully this will turn a few heads.
The boards are populated with WS2812 addressable RGB LEDs, more popularly known as NeoPixels to hobbyists such as myself. Power is bussed around the edges and boards joined electrically and mechanically at the corners.
The top surface distributes ground while the base surface, which you will see in later photos takes power from brushed contacts, distributes positive voltage.
For the lower panels I moved to MAKLab’s Roland MDX40 and using VCarve to generate toolpaths I saw a dramatic increase in speed, being able to churn out several panels in one sitting.
The batch of lower panels which I forgot to drill and ended up hand-drilling.
A peek at the mess inside before it was closed up. The 5v stepper motor (28byj-48) with trimmed down driver board has sufficient speed and torque for this application. Resting on top of the driver board are five WS2812B’s on individual boards (bought as a set of 50) which give the finished dodecahedron a soft internal glow. The glow shows up where the copper has been milled off and at the edges. The mess of orange wires carries the LED data from one panel to the next.
Close-up of the finished article. I used a dremel polishing wheel to shine up the copper boards before applying clear nail varnish to hopefully seal the copper against oxidation.
Microcontroller is an ATTiny44 running at 8MHz off its internal oscillator, it was programmed using Arduino with an Arduino UNO serving as the ICSP programmer. In this photo you can make out the circular tracks around the motor shaft which accept power from the brushes (module connectors) on the base.
Want to see it in action? Here’s a Vine while I edit together a video of it in action:
What will you make?