Tips and designs for 3D printing electronics with F-Electric

  info@functionalize.com

Since we’ve started shipping, I wanted to share some tips and tricks with you, so you have the best possible F-Electric printing experience.

First, the basics… many people have asked what print settings to use, do I need a heated bed, and will it bond well to PLA?

In fact, print settings for F-Electric are quite close to a fairly high temperature PLA, meaning a nozzle temperature of about 215-230C with no cooling fan, and any bed temperature, from room temperature to about 65C, and yes, it bonds quite well to PLA. One thing that you might find useful is the fact that F-Electric not only has a bit higher strength than PLA, it also keeps its form better (dimensional stability) and shrinks less than normal PLA. The bottom line is that we’ve found F-Electric to be a fairly forgiving print filament. For maximum electrical conductivity:

  • keep the temperature 220C or higher
  • if possible, the print head travel direction along the line you want electricity to flow
  • don’t use a PLA cooling fan

Now let’s cover a few part types, such as traces, our flashlight, sockets, circuit boards, power connectors, etc.

Traces
An important thing to remember about traces is that there are ideal traces, where the print head makes a direct line from one end of the trace to the other, and then there are cross-hatched traces, where the head goes back and forth in a direction not parallel to the flow of electricity. As you might guess, ideal traces are much closer to the best conductivity you can get. Cross-hatched traces will typically be consistent for any two parts that are printed exactly the same size with the same cross hatch, but what their conductivity will actually be is much harder to predict. For that reason, I always try to design for as close to ideal traces as possible.

One way to be sure that the printers head prints your traces ideally is to keep their width at or under 0.8mm for today’s common printers. For any amount of F-Electric you use, I have found that 0.8mm traces are the widest that generally always print with an ideal path. You can adjust the conductivity by choosing 0.4 or 0.8mm in width and varying the height of the trace with a predictable outcome. Try printing a few test traces to see. If you need more conductivity than you can get in about a 0.8mm wide x 2.5mm tall trace, you should consider more than one trace in parallel, separated by a 0.05 or 0.1mm gap, which will prevent your slicer from making cross hatches to print the trace.

In the image below, you can see an example on the Arduino light sensor shield, where a short trace from power to A0 input serves as a resistor, while the connection on the other side of A0 to ground, which is intended to be a variable resistance sensor, serves as the other resistor in a variable voltage divider. With this simple configuration, the Arduino can measure analog input from a large variety of sensors.
Different height trace example

In this second image, you can see an example of parallel traces, used to increase the amount of current that can be carried from the power connector to a transistor and other elements. The vertical traces also help improve the conductivity to a threaded power connector, which is screwed into the tower.
LevitatorPowerConnector

My first flashlight
While this design has its flaws, for example, no ideal traces that could improve its brightness, over-complicated battery socket, etc., this old and first flashlight design has a nostalgic value to me, and it has assembled from the beds of many printers since this version was complete. I’ll give a brief description and simply include the step and STL files for the design here. Please share at least photos of improvements you make, if not designs on our facebook page.

The most interesting electronic features of the flashlight include a wire snap-clip, that actually gets a fairly decent connection, and the fact that its on/off button is actually a pressure sensor, due to the pressure-sensitive surface resistance of F-Electric material. The clear pressure sensitivity left me wanting to make many things that I hope you do, such as touch sensitive keys or other types of pressure or fit-sensors in your own devices.

The snap clip has two outside channels and one channel that fits between them, which have inner contours that cause them to clamp and pull on a wire when the flashlight is closed over it. By putting the cathode of an 8mcd or greater, 20ma, 3, 3.4V, or even 3.6V LED into the channel, the anode, bent up slightly in the middle of the battery socket, placing a 3V 2016, coin cell battery over it, and finally closing the device, you will get a solid connection on the snap clip, and your flashlight will be complete.
OpenFlashlight

You can download the flashlight and arduino board here. My next post will be more detail about the Arduino board and how it works. Until then, I’ll wrap up for now with a couple photos of the two working together. As you can see, while no light is shining on the photoresistor, the LED on the arduino board shines fairly brightly. The more light it senses, the dimmer the LED gets until it eventually turns off. Any sensor based on resistance can be used in place of the photoresistor. Since F-Electric is the most conductive 3D printing filament you can buy, for best results, use F-Electric. These parts were printed with version: FE-PLA-0750.
ArduinoBoardArduinoActivated

First flashlight files
Arduino photosensor files

Creative Commons License
This work by Functionalize Inc. is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

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