Oct 28, 2016 | By Alec

If you haven’t decided on this year’s Halloween theme just yet, how about a Terminator-style party? Duke University graduate student Patrick Flowers could be doing that himself, as he just 3D printed a very cool Terminator head complete with shining, blood-red eyes. While cool in its own right, the head is simply a vehicle for a very potent new copper-based 3D printer filament called Electrifi, which was 3D printed into the circuit that lights the Terminator’s glowing LED eyes.

This cool filament is being developed by startup company Multi3D, with Electrifi being their first filament on sale. The startup is being run by Flowers and a few labmates from Duke, where Flowers is a PhD student in the Benjamin Wiley’s lab. Together, they are pioneering a number of copper-based 3D printable filaments that stand out for their extreme conductivity levels. According to the company, Electrifi is about 100 times more conductive than other metal-based 3D printing filaments on the market, and they have already taken out a provisional patent on the material.

Of course copper-based materials can be found all over the place, but as Flowers explains there’s a lot more to conductivity than simply mixing some copper with PLA and pressing print. “Copper is really conductive originally, but if you try to extrude it out of a hot nozzle like you have to do in order to do this 3D printing, then it quickly loses all its properties,” Flowers explained, adding that using those heat-resistant conductive materials like silver are too expensive to use on any larger scale.

To overcome this obstacle, Flowers and his team are therefore mixing copper with other materials to help it stay conductive throughout the extrusion process. “This lab has a long history of working with copper – copper nanowires, copper particles, copper nanoparticles – so we’ve got a lot of little tricks that we use to maintain the conductivity,” Flowers added.

Right now, they have found particular success with Electrifi and are extensively testing its limits. The Terminator head (based on this T800 head model by machina) perfectly showcases the material’s potential. “The circuit inside this guy is really simple, but it does show the capabilities of the material: it is embedded, it shows that I can go down, over, up, out, and go to a couple of eyes,” Flowers said. “Now I want to expand on that and show that you can make these really complicated embedded structures that have multiple layers and multiple components, other than just LEDs.”

In the meantime, you can already 3D print this fantastic Terminator head at home. Most of the head is actually just made from PLA, with a dual extrusion system being used to embed the conductive Electrifi filament into the print. A fantastic 3D printing tutorial can be found on Instructables, but the process is fairly straightforward.

The biggest challenge is actually embedding the conductive channels in to the head, which can be done using Simplify3D. “For this print you will need to add a gcode command to your starting script to allow for cold extrusions. Open up process 1 and go to the scripts tab. Under starting scripts, scroll down to the M302 command. Check this link to verify that the syntax for M302 command is correct for your firmware and make corrections, if necessary,” Flowers says. The same needs to be done for the second process.

The other thing is that 3D printing a conductive filament not always works well on all 3D printers, and Flowers therefore recommends Dglass3D’s AutoLift all-metal hotends – which have an excellent mechanical retraction feature that eliminates the cross-contamination problems often seen in dual-extrusion setups. “When 3D printing a circuit, if you have cross-contamination problems it will lead to shorting in your circuit. In my experience it is necessary to use slightly lower printing temperatures with the AutoLift hotends in order to maintain enough downward pressure on the nozzle,” Flowers says. “This keeps the nozzle in its proper printing position. I set the mechanical retraction for these hotends to 0.5 mm. Also, I did not use the S3D prime tower but rather I made my own.”

The Electrifi filament itself was 3D printed at 150°C on a heated printed bed (75 °C), at a 100 percent infill at 30 mm/s. A pair of Electrifi contact pads can be used to install the two 5050 SMD red LEDs in the eyes of the Terminator, which can be placed using a pair of tweezers. While a bit tricky, all necessary steps are carefully covered in the tutorial. A 7 V Lithium Polymer battery and a JST connector are subsequently used to light up the eyes and scare you every time you walk into the room.

 

 

Posted in 3D Printing Application

 

 

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S wrote at 10/28/2016 11:47:56 PM:

Come on, it was 3.7 V lithium polymer battery!!



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