Some thoughts about making water-sealed 3D printed containers.
I’m reading about an interesting water seal test undertaken by Reddit contributor JoshHawk. “Hawk”, a mechanical engineer, was interested to learn whether a 3D printed container could be sufficiently sealed to pass the IPX waterproofing test.
The IPX rating is a scale that tells you the level of waterproofing of an item. The first part, the “IP”, stands for “ingress protection”. The following numbers indicate the level of protection. The first digit represents a 0-6 scale of solid particle ingress (e.g. dust), while the second 0-9 scale represents fluid (water) ingress protection. If there isn’t any data, then the digit becomes “X”. For example, an IPX3 would provide limited water protection (sprayed water), and an IPX8 would provide very good water protection (1m deep immersion).
At first I thought this was laughable, as my previous tests with waterproofing 3D printed parts were miserable failures. FFF 3D printing invariably leaves tiny gaps between layers, and that’s where leaks happen.
But that was with rigid materials. Here JoshHawk used TPU instead — and not just any TPU. The material was Bambu Lab’s TPU, which has a durometer rating of 95, meaning it is quite stiff, but still barely flexible. Stiffer TPUs are easier to print, likely why Bambu Lab chose that level of hardness for their TPU.
This is quite an interesting concept: the slight flexibility of the material could allow for tighter seals than printing with purely rigid materials.
Did the test work? JoshHawk explains:
“The test dictates that you wait 30 minutes but I chose to wait an hour. After removing the container and opening it, the strips remained white (No water detected). The lighter still worked and there was absolutely no water inside.”
While this was an informal test, it seems to match the IPX7 standard (30 minutes at 1m depth). Quite impressive!
What was the trick to achieving this level of waterproofing? Aside from the choice of material, JoshHawk used four perimeters, which would lessen the possibility of layer line leaks.
And there was an interesting design choice:
“Through my trials, I have found that TPU face seals will work significantly better than perimeter seals. Perimeter seals will be less waterproof due to the sealing surface being against the layer lines and seam, which will allow water to seep in.”
So it now appears that it is indeed possible to make properly waterproof containers with desktop FFF 3D printers.
Via Reddit
