I was thinking about conducive filament, currently everyone making these filaments are simply graphite and pla/abs. In conducive gaskets/elastomer the companies mix graphite with nickel, silver, or other metal. The graphite seems to mix more evenly and the metals defiantly conduct more. Is there any filament makers playing with this idea?
@taulman_ThreeD
@Joseph_Chiu
Others I can’t remember right now.
Here is a link to conducive elastomers I am taking about.
http://www.chomerics.com/products/emi/gaskets/cond_elast/index.html
I’ve heard that the best conductive plastics are made by using a combination of carbon and silver or a similar metal. The idea is that while the metal is more conductive, the carbon is better at making connections through the polymer (metal particles alone tend to have poor contact with one another). I don’t know of any filament producers actually using this method, but now that we’re starting to see metal-filled filaments, I wouldn’t be surprised to see it.
I use black carbon 2000 for my conductive filament. Not ready for prime time… Maybe never. But no graphite. Some have perfected the method I’m using. Talked to a guy who claims they have it working with graphene. Another guy says his filament is 1 ohm. Others use paste, akin to conductive ink. It’s coming, but it’s hard and it will be expensive.
@Brook_Drumm if what he actually said is that his filament is “1 ohm”, he doesn’t know what he’s talking about, because resistance through a conductor is proportional to the length divided by the cross-sectional area (ignoring surface resistance).
1 ohm for cubic cm of filament. Sorry should have been more specific
@Camerin_hahn Reducing resistance with Graphene is an approach we and others are looking at now. Simple Graphene loading already shows a lower resistance than carbon loading, but we’re not at the “1 ohm for cubic cm” just yet.
Graphene doesn’t make sense. Graphene is a 1 atom thick layer of carbon. I guess the advantage is smaller chunks of graphite(clumps of carbon with no specific layer thickness). Black carbon should work well, should be very similar to graphite. But the reason you add metal is do you can reduce your “conductor” to “plastic” ratio. When you are using only carbon there will always be a high resistant value, you cannot do better than solid conductor so and carbon is not a great conductor. (Iron is 1000 times better)
If you reduce your plastic to conductor ratio your plastic should be easier to print. I would be really interested to try a graphite nickel mix as many makers of rubber mixtures are claiming 0.1ohm per cm^3. And still rubbery enough to be used as a water tight gasket.
@Tom_Martz I would bet mixing metals in with graphite will not only be cheaper, but also better than graphene. Graphene is so fam expansive. Also it works in rf/waterproof gaskets, that is a super tough problem to solve. Conductivity needs to be high and elasticity needs to be there to.
@Camerin_hahn you seem to be really engaged in this problem. Why so interested? You thought of building a Lyman extruder(or similar) and experimenting? Just wondering
@Brook_Drumm I just got my NDA exclusions finalized for contributing to RepRap (been a few months coming). I am out of space in my cave so i cant actually fit an extruder. I have been wanting to do electroplating to plastic selectively to design antennas. By using 2 extruders, one conductive and one standard plastic.
I am a Radio Engineer with a background in antenna design. I am looking for a way to move more quickly while designing antennas. I have an electroplating rig i put together, i have tried a couple types of conductive filaments, but they are not “conductive enough”.
@Cliff_Bramlett The copper wire core in the filament doesn’t work for obvious reasons, placing it in between layers would be really difficult as the direction you are traveling changes rapidly.
@Camerin_hahn did you see the recent story about painting with a mixture of graphite and acetone to make a surface conductive for plating? This surface-only conductivity seemed to work better for reliable coverage, because a conductive core results in lower I resistance areas further from the electrode, and the higher resistance areas in between can get no plating.
@Camerin_hahn , I was really just trying to get a conversation going, and hadn’t refreshed the page enough to see that one was already started. 
@Cliff_Bramlett no worries.
@Whosa_whatsis selectively painting does work. It is what I do now(have been unable to post until recently). I would like to avoid hand painting complex shapes, if I could 3d print said shapes I would be able to design more interesting structures.
If you got the right combination of conductor concentration, solvent potency, and viscosity, you could dip the print in the solution (more of a suspension, really) to coat it. Of course, if you don’t want to plate the entire surface of the print, that’s a different problem. You might be able to solve it using channels that you pour the conductive mixture into, but that limits your ability to make 3d shapes.
I definitely do not want to electroplate the entire surface.
Think of the link below with a 3d printer. It needs to be electroplated as the carbon is not anywhere near conductive enough.
http://www.sciperio.com/antenna/antenna-fabrication.asp
How about
1). 3d printing a 1mm square or rectangle-- any flat shape will do.
2.) Then print a matching shape 2 or 3 layers tall, but with traces for a circuit as voids. You may need bridges to hold some pieces in place.
3.) Spray adhesive can temporarily glue the two smooth sides together.
4.) Paint with the acetone/graphite/carbon black/etc slurry with a big brush- fast and messy
5.) pull off mask and let dry
6.) copper electroplate the traces
7.) dance a jig. You just made a circuit board with your 3d printer. One you can solder too!
Now get creative and try a cylinder, a two sided board with vias, print the vias across long gaps as cylinders or bridges (a psuedo two layer with only one layer plus bridges), turn corners with traces to put electronics on top and sides, make circuit on a wavy 3 dimensional surface… Put it on a Möbius strip, make something the world has never seen.
I don’t think ice seen this done. I’ll race you… Someone will be the first!
Brook
Making traces by electroplating will be tricky because voltage has to be applied to all of them, but you might design an object with raised surfaces everywhere except for your traces, electroplate the whole surface, then grind off the raised portions to separate the traces from one another.
I have tried that process, but the conductive filament I have tried is not conducive enough.
My thoughts are make most traces near the edge and face a “break away” section that you could toss after plating.
If we are going to make it a race we should have a set design. Any preference for a circuit?