Hello lemgineers!
I’m working on designing a claw that can be operated underwater. The plan is to use a linear actuator in a waterproof housing. The main issue is allowing the shaft to slide through without causing a leak. What’s the best way to go about this?
Sorry I’m just now seeing this, and late to the party is just fine 😍 I’m looking at redesigning it this year anyways!
I’m not sure if this is similar to what you meant by an accordion covering, but what we did was design a mold that we 3D printed and poured silicone into to create a seal/cover that will stretch as the piston of the linear actuator slides in and out.
I meant with the pleats, similar to what you see on an actual accordion, or in a bendy straw. It’s how they did the joints on the Apollo space suits, for a vaguely similar application. The shape is sometimes called “bellows”, but that’s pretty confusing when it also refers to an air blowing technology that may or may not involve a diaphragm of any kind.
If you got enough range of movement with just a straight elastomer cylinder, that works, but if the pressure is pretty modest a variety of stretchy ducts made for HVAC or other home purposes are sold. I have some for draining rainwater, but they seem to break in stiff wind, so YMMV. You could also mold your own again.
We actually did start out with an accordion/bellows design, but found that the flexibility of the material alone was more than sufficient to handle the required distance of travel on the actuator piston!