(I thought that was a bit catchier title than, "Conductive Filament Part 2." At least it gets fewer conflicting hits on Google, right?)
I meant to post this earlier in the week but as the title subtly hints, I was laid off on Monday. That took a bit of wind out of my blogging sails this week. Ironic, given that I've abruptly had time on my hands. On the plus side, I'm interspersing my job search time with 3D tinkering and helping get the new 3D printers set up at my daughter's school, so...let's do some more filament testing.
In Part 1 of this subject I started testing the actual conductivity of STAR Alchement's Conductive ABS Filament. In technical terms, the results were middlin'. While my printed coupler did conduct electricity, it dropped the 8V output from my battery to just over 4V. I decided to change a few things on the next attempt.
The coupler in this experiment is regular ABS (Hatchbox Gold, not to be confused with the awesome double album, ABBA Gold) while the inside is Alchement's Conductive. The sockets are the same size cones described in the first blog; the wires pressure fit snugly into the ends of the block. Each cone tapers down to a 2mm diameter cylinder, and the entire arrangement is 40mm long.
One other key change -- I separated the processes and used different infill densities. The gold box is 25% infill, same thing I use for most prints. The conductive part, however, is at 90% infill.
Similar test to before. Measure the battery output alone, then add the coupler to the circuit and measure again. No need for a "before" shot this time, it's pretty much the same as the first time. (It's the same battery, same battery clip, and I promise I haven't been running my Walkman off it in the intervening week.)
You can see the results below. Although the voltage still isn't at the full 8V the battery was putting out before, it's much higher at 6.26 than the 4V from the first piece that I printed. It was also quite steady. Once the wires were seated firmly the reading hardly budged. The obvious conclusion is that the 90% infill made the major difference.
Next steps will be trying a few more variations of the "wire." The connecting wire here is 2mm diameter over 20mm (each of the sockets is 10mm deep) and perhaps that volume causes more diffusion. (Mike Patterson, if you're reading this, stop laughing. My line is business intelligence, not electrical engineering.) After a visit to PAX South this weekend I'm going to print more models with 1mm or .5mm wires and see if I get any noticeably different results.