I have a piece of test equipment that needs to stay underwater for days. Normally I would use or make a waterproof case with a lid and a gasket.

Instead, I’m wondering if I could print a box, pause the print just before the top face, put the device inside and then print the top face over it. No openings, no nothing, and the device works by induction so it doesn’t need to physically connect to anything.

But this would only work if 3D-printed PLA walls are really waterproof. After all, 3D-printed features are kind of a bunch of wires more or less loosely attached to each other, so I wouldn’t be surprised if water could leak through under pressure.

Before I spend any time assessing this myself, has anybody tried printing waterproof enclosures?

  • dual_sport_dork 🐧🗡️English
    29•10 hours ago

    Watertight and waterproof are not quite the same thing.

    Almost all 3D printable materials are waterproof, in that they will not dissolve in water. (With the exception of, e.g., PVA which is sometimes used as a dissolvable support material.) I realize this is not the intent of your question, but a lot of people seem to get it twisted about various polymers absorbing moisture/being hygroscopic/becoming “wet” and therefore believe that they literally melt or soften in water over time or something. This is not the case.

    3D prints can be made watertight but it does not necessarily follow that all of them are by default. This will be dependent on your print settings and, to a certain extent, your print material. Some materials are more isotropic than others and the layer lines stick together more readily without gaps. TPU leaps to mind, which can be made extremely watertight very easily.

    Use a lot of walls – another poster recommended 4, that’s probably a good place to start. Don’t forget to increase your top and bottom layer counts as well. You may need more top or bottom layers than walls, because your layers are probably thinner in the Z axis than your nozzle extrudes in X and Y. If dimensional clearance is not an issue and in your case it seems it isn’t, consider increasing your extrusion multiplier slightly in the walls as well, to ensure that material is squished into any potential gaps. Avoid sharp corners or tiny points on your model, which upon slicing may be incompletely filled. Avoid long unsupported bridges as well, because the couple of layers where these inevitably sag will wind up non-solid. If possible, make the outer shell of your model an exact multiple of your wall extrusion thickness so your slicer will not have to guess at any areas and try to fill them with tiny points or similar. If you play back your slicer’s preview of a single layer you’ll see what I mean.

    If you really want to employ the nuclear option, instruct your slicer to iron every single layer. This will make your print take forever, but each individual later will be extremely authoritatively bonded together in the X and Y axes, with no gaps.

    If failure is not an option, coat your object after completion with Flex Seal or Plasti-Dip or something.

    • @[email protected]OPEnglish
      14•10 hours ago

      Yeah sorry I meant watertightness.

      I’ll experiment. But yeah, failure isn’t an option in this case, so I’ll go with the safe option of using a box that I can sue the manufacturer of if the seal fails, rather than me having to explain to my boss why our equipment is ruined 🙂 At least for now.