Scientist and researches are rapidly breaking the barriers of 3D printing, but one obstacle has stood in the way of fully printing many items; the ability to print electrical components like wiring and switchboards. However, a group of students from the University of British Columbia may have found part of the solution by using a mechanical pencil.
Jacob Bayless, Bing Dai, and Mo Chen approached the problem of embedding wire in a 3D print as part of a project for their engineering physics class. While earlier efforts to embed conductive materials were made by melting and printing alloys into an object, the group wanted to use copper. Copper is a preferred conductor of electricity, but the downside is it doesn’t melt. “We therefore sought to create a tool that prints wire directly,” said Chen, in a video later released by the group. This was accomplished by using a mechanical pencil.
The team used a servo to push the button that would normally expel the lead. In this case, it expelled the copper wire from the tip of the pencil. After testing this setup, the group determined it would work and the final tool head used this design.
Another obstacle to overcome was how to cut the wire. Because the wire doesn’t melt, the students needed a cutting mechanism. The first design used a shear cutting mechanism. “Our cutter design was a brass insert fit into a steel tube with holes drilled to line up,” said Dai. “A solenoid then moves the insert, sliding the holes out of alignment and shearing the wire.” After testing this design, it proved unsuccessful and the team went back to the drawing board.
The three students didn’t prove a successful design for the cutting mechanism and ended up manually cutting the wire. In the final report they recommended that a new method would have to be developed to successfully cut the wire.
The team discovered that while copper does not melt when heated, it does form a strong bond with thermal-plastics. They decided that this was the best method to embed the wire and so they incorporated a heating element into their plan. The heating element is similar to that used on a plastic extrusion 3D printer. The element heated the wire as it was pushed out of the pencil, which caused it to bond to the plastic.
The final piece of the copper metal printer was the software to move the machine head. The students used G-code which is popular among the 3D printing community. “We wrote a MATLAB script to generate customized G-code for different patterns such as spirals, said Dai.” “This greatly reduced the effort involved in printing new designs.”
In the end, the three students didn’t print an electrical circuit but they did prove out the idea that electrical wire can be embedded into a 3D print. This gives researchers and hobbyists a foundation to further build upon.
Read about the project in greater detail at: http://www.reprap.org/mediawiki/images/2/25/SpoolHead_FinalReport.pdf.