One of the projects that came out of our 3D printer project brainstorming event was the idea of making a machine that can 3D print electronics.  Impatient Inventor and I have decided to pursue it.  If we are successful, then new possibilities are opened up in design and manufacturing.   Instead of figuring out how to the electronics and mechanical parts separately and assembling them, you can make a single object that integrates both.  Imagine being able to make anything from multilayer circuit boards to car doors with integrated wiring on a single machine.

Ideally, the 3D printer would be able to put down plastic, wiring, and components.  To start out, though, we will make a machine that just puts down wiring and plastic.  CNC gantries and plastic extrusion are solved problems, so we began by prototyping an electrical wire extruder.  We picked up a four axis router for the gantry and are still looking around for a good plastic extruder.

For our first wiring compound, we chose solder due to its low melting point and strong conductive properties.  To ensure that ABS and solder played well together, we jammed solder into a soldering iron and letting it drip on a raft left over from a 3D print job.

It turned out all right, so our idea of using regular solder for the leads seems viable.

For our next version, we wanted to see if we could do it in a more controlled way.  Pulling this off took a couple of advancements:

• To see if we could precisely control the solder application, we 3D printed a block with a channel instead of using the left over raft.
• To prevent the solder from flowing everywhere, we opted for flux-free solder instead of solder with flux.
• To better control the flow rate, we put the solder in a nozzle that we hose-clamped to the soldering iron tip, instead of putting solder directly on the iron.

3D printing a block with a channel
We wanted to see if we could get the solder to fill out a 3D printed channel.  So, we started out by drawing up a 3D model in CAD software (SolidWorks).

We then used 3D printer CAM software (ReplicatorG), to convert the the 3D model into instructions for a 3D printer (gcode).

Finally, we sent the instructions to the 3D printer (a MakerBot Replicator).

The result was our 3D printed block with a channel in it.

Turning the solder nozzle
We then made the nozzle that would put down the solder.  We started with a small aluminium rod that Steve generously turned down for us on a lathe.

Our solder nozzle:

Using a hose clamp, we fastened our nozzle to the end of a soldering iron and the next version of our extruder was born.

Testing it out
We pushed the flux-free solder into the nozzle and to test our newly minted extruder on our 3D printed block.

This is what we got.  Not the most handsome wire, but…

It is functional!

In the next version, to further improve the flow control, we will use a pump to sputter the solder out at a defined frequency.