Since the crew at [CPSdrone] likes to build underwater drones — submarines, in other words — they need to 3D print waterproof hulls. At first, they thought there were several reasons for water entering the hulls, but the real reason was that water tends to soak through the print surface. They’ve worked it all out in the video below.
Since the printer is an FDM printer, it isn’t surprising that the surface has tiny pores; even the tiniest pores will let water in at high pressure. They tried using epoxy to seal the prints, which worked to some degree. They did tests using an example submersible hull that you can try yourself if you like.
It took quite a few tests to find leaks. At 10 cm of water pressure, the prints did well. However, the deeper you go, the more pressure is on the hull, and you get more water inside or, at least, soaked into the plastic. To figure out the difference, they repeated the tests with solid models and found that some water gets inside and some of it is soaked into the layers.
The next step was experimenting with dichtol, a smelly chemical that waterproofs prints via a soaking process. Repeating the experiment showed very little water ingress, even at high pressures. The dichtol soaks into the plastic like water and leaves behind a resin when it evaporates.
The final step was to try a resin print. The results were a little skewed because the hull was still full of resin, which didn’t allow for a full test. The resin wasn ..
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