If you’ve taken a look at some of my previous experiments, you may have noticed that one of my biggest issues when incorporating electronics into my prints has been the wiring. Most of my background in engineering has been on the mechanical side of things, so my circuitry is not the cleanest, as you could probably tell.
This past week, I visited a 3D printing company in Somerville called Voxel8 (you can check out their website here). Their printer has a few features I’m very excited about, and their system revolves around the two extruder heads their printer carries. One of them extrudes PLA, and the other extrudes a conductive silver ink. My experiences with other types of conductive ink have not been very positive; I had once attempted to print a circuit out or MatterHackers conductive ABS filament and the filament had such a high resistance given its surface area that it might as well have been normal ABS. I had really wanted to incorporate a circuit into my print, which brought about my “Prints of Light” post, where I got a light to turn on at the end of the print. The wiring for that print was pretty trivial, it was just an LED, two batteries, and a switch, but it was very difficult to push the wires and components into the print job nicely for a variety of reasons. I also had this issue in my last experiment, when the extruder head shorted some of the wires during the print.
Project Wire, the software developed for Voxel8’s printers by Autodesk, allows you to import your .stl file, draw out the wiring inside the part, and place electrical components into the parts that the slicing software will then account for. The conductive ink extruder draws out the wiring paths during the print, thus “embedding” wires into the PLA print job. While at their space space, I was given the opportunity to play around with the software and CAD up a part to be printed (unfortunately I didn’t have enough time to print it out). So I decided to make a simple pushbutton flashlight.
The difficult part about designing for coprocessing that I have encountered involves determining the spacing and the tolerances for coprocessed components. All I needed to do was CAD the shape of the thing that I wanted, and then I could use Project Wire to figure out everything else. I simply placed in mockups of the components I wanted, told the printer to pause at the layer I wanted it to, and the software handled the rest of the tolerances, slices, and fits.
It was a bit tricky working out how to draw the wires connecting the components, mostly because thinking about wiring things in 3 dimensions was a bit of a brain teaser. Most circuit boards are flat, 2 dimensional boards with the components placed on a face of the board. When they do extend into another dimension, all that usually involves is another circuit board mounted on top of the first one. It’s all very planar and standardized. The Voxel8 printer gives you the freedom to play with your circuit and allow it to take whatever shape or form you want. Just the idea of being able to quickly and easily design 3D circuit boards made my mind wander. I sketched up my circuit inside my part and here’s what I ended up with:
Notice the round object to the side of the main body of my print. This is a pushbutton designed by one of their employees. The spring-like segments allow the middle section to deflect up and down, and the middle of that part has a spiral of conductive filament on it. Midway through the print job, with that part of the print complete, it can be pulled off the build plate and placed into the main section of the print at the same time the batteries and the LEDs would be placed. Underneath the cavity where it would be placed, you’ll notice there are two wire paths leading into the center of the cutout. When the final printed product is complete, if the button is pushed, its conductive pad connects those two leads to complete the circuit.
Voxel8’s printing system has a lot of potential to change the types of things that come out of 3D printers. Instead of printing all plastic parts that will either end up as trinkets or pieces integrated into larger assemblies, Voxel8’s printers can produce genuinely integrated, functional content. This is one of the reasons why I’ve been developing and researching the coprocessing method in the first place, and I hope to work with their printers and software a bit more to see what I can do!