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Waterproofing

A project log for BorgCube ROV

Underwater robots!

tim-wilkinsonTim Wilkinson 12/12/2015 at 00:130 Comments

There are a couple of general options to waterproofing electronics.

One is potting, the process of encasing your electronics in epoxy (or something similar) to keep them free from water. The big advantages with potting are that you can pot randomly sized or shaped devices and boards, and that there's no air-spaces left to be crushed at high pressure. The downside is that the electronics are permanently sealed away; so hope there's no failures.

The alternative options is to place the electronics in some sort of pressure vessel; the vessel keeps the water out, but allows access to the electronics when not in the water.

I expect to use both kinds of waterproofing in this project, but for the moment I'm thinking about a pressure vessel for the Raspberry Pi board.

I went through a few iteration on this. My original plan was to simply by an Otterbox (or equivalent). When their not making iPhone cases, they also make dry-boxes for divers. They seemed simple and ideal for keeping the electronics dry. However, I never could find a box that was the correct size for my craft and that was rated for sufficient depth.

So my second plan was to build some sort of sphere to contain the electronics. For this I'd use two polycarbonate hemispheres with flanges, and bolt them together. And while this is still a very appealing idea, it would require me to build a plate between the two spheres to contain the o-rings and grooves necessary to keep the contents water-free. I decided that was too difficult to do right now.

The third plan, and the one I'm using, utilizes acrylic tubes I bought from Blue Robotics. This has the advantage of being specifically design for underwater work, and comes with the necessary endcaps and o-rings to keep the inside water free.

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