Yep, You Can Run Your 3D Printer Underwater

Modern 3D printing is an open source success story. The rapid rise and refinement of hobbyist 3D printing is a direct result of open development by the community. Over the years, we've seen many ideas put to the test and many of them seemed silly at first. That's why we applaud the CPSdrone team for their recent experiments in underwater 3D printing.

Why would anyone want to run a 3D printer underwater? The CPSdrone team's initial motivation was cooling. Your typical FDM (Fused Deposition Modeling) 3D printer works by melting thermoplastic filament and then extruding that molten plastic to form a part. Heat is necessary for extrusion, but bad for almost everything else. In an ideal world, the extruded plastic would cool enough to solidify the moment it bonds with the previous layer. Most printers have cooling fans to speed up that process, but the CPSdrone team figured that water could do it faster—thereby improving overhang and bridging performance.

Is is also possible that the buoyancy of the filament in water could further improve overhangs and bridges, as gravity would have less of an effect.

To test their theories, the fellas at CPSdrone had to submerge a 3D printer. They chose a Prusa i3 clone as the test subject. That required some waterproofing, but probably not as much as you're thinking. Contrary to the popular perception, electronics can work underwater. Deionized water has very low conductivity and that helps, but electronics can even work in salty, high-conductivity water as long as there aren't exposed contacts too close together. If the resistance (a function of distance and conductivity) is low enough and the voltage high enough, you get a short circuit and that's a problem. Otherwise, everything keeps working as long as significant corrosion doesn't occur.

So the CPSdrone team only had to coat contacts that were in close proximity in waterproof epoxy to prevent shorts. They also swapped out traditional ball bearings for Delrin bearings that can't corrode. Finally, they embedded the hot end in a brick of silicone. That keeps the water from cooling the hot end, which must remain at a high enough temperature to melt the filament for extrusion.

Submerged in a fish tank of deionized water, this modified 3D printer actually worked pretty well. There were some mishaps with the team's choice of silicone for the hot end, but overall it was a success. Tests in a pool weren't as promising, as the printer ended up failing during the team's visit to a local pool.

The real question is whether any of this was worthwhile. The submerged printer did seem to handle overhangs better than the control printer, but not enough to make us want to go buy fish tanks for our printers. The difference in bridging wasn't substantial enough to be conclusive.

Either way, this test was very interesting and we're happy that the CPSdrone team was brave enough to take on the challenge.