I’m working on a research project and will be building an ROV. I will be 3d printing the body and other structural parts. I have a separate enclosure so these parts do not need to be water tight. I expect a max working depth of around 200m and 1-4 hour deployment (maybe longer).
The first question I have is material. From the research I’ve done I’ve found that PETG would probably be the way to go but am still open to other suggestions.
My second question is in regards to print settings. My first thought is that using infill leaves air pockets in parts. I understand that prints are not watertight and worry about the effects of water forcing its way in to fill the gaps with every deployment. If I somehow seal the parts to prevent water from permeating through, then I worry about crushing. Using more wall layers and/or 100% infill greatly increases cost, weight, and print time.
I would greatly appreciate anyone willing to share their knowledge and experience.
Hi @samkron -
No need to go to so much trouble, sealing parts to make them water tight will lead to heartache. Embrace the flooding!
I’ve tested printed parts to full ocean depth - they maintain physical strength even when filled with water. Use gyroid infill, and droll a couple of holes in key locations through the prints “skin” so when retrieved, they drain (and maybe some higher-up holes to promote the fill.)
2-6 perimeters, more for strength, and 10-25% infill should be fine for most applications! Printing with a .6 or .8mm nozzle can really give you much stronger parts thanks to the larger extrusion width.
PETG is my go to, but ASA can be good for applications where UV resistance and maximum strength is required. Avoid filaments with CF fibers in them - those fibers can be hazardous to both your health and the oceans!
We can confirm PETG and ASA work good, but PP is lighter and more durable (and less toxic) and PP-CF is the best we’ve found to date. (use caution when printing, but the fibers stay in the material once printed). For testing prototypes, PLA works great, it’s just heavy and cracks more easily.
For smaller parts, we use 100% infill, but on very large bodies (like our 3d printed Midway ROV frame) we manually make a 5mm thick shell and support ribs in cad, and have vent holes top and bottom as Tony suggested. Properly printed PP-CF is about as strong as machined plastic and will last years in water and sun, but it’s also lighter than water and doesn’t crack due to hard impacts.