I tried a solenoid I scavenged from underwater valves on my 3D printed valve system and it didn’t work (duh). It was just too weak. The original valve spreads the force from the high-pressure side across a larger area, so I guess the spring return can be comparatively weak. My design didn’t do that. I also didn’t cut my compression spring down very much, but I qualitatively determined that the solenoid wasn’t generating a useful amount of force by holding it on the magnetic core while turning the power on and off a bunch of times. I am a terrible engineer.
So I went back to square 2 and decided to remake the original brass valve body in lighter ABS plastic using our Makerbot 3D printer. The beta version looked like this: Continue reading
I’m having trouble with the upper valve that will allow air to be released from the hull (thus decreasing buoyancy and giving some downward thrust). I mean, I’m having trouble with everything, but that’s why I’m doing this, right? Anyway, I decided to order a couple underwater solenoid valves in the hope that I could stick one in the robot and have it work (hahahahaha). I found several suppliers in China listed on this site alibaba.com, and settled on Nuoling Pneumatic. Most of the other options either weren’t waterproof, were too big, didn’t support a 12 V power supply, or had a large minimum order size. The two I bought were $12.35 each, which is less than I was expecting (although the shipping was $55 for two units).
Underwater solenoid valve from Nuoling Pneumatic
The valves were a lot bigger and heavier than I expected. You can see it’s basically a big chunk of brass connected to the waterproof electrical components. Fortunately it’s easy to take apart: