Step 5: Install pneumatic cylinder and switch

The pictures are bit out of order because I installed the pneumatics first to test the whole thing out and then removed them to paint.

The 6 inch throw, 3 inch diameter double-acting pneumatic cylinder was a backup from another project that acutally needed such a thing. The valve is a 4-way, 2-position lever-operated control valve (part #4493k34 from McMaster-Carr). Both items are kind of pricey, so since being purchased originally for a consulting project they have been reused in a number of other projects. Compressed air is generated by a portable compressor used to power the air flow on the Squid Labs laser cutter when we take it to conferences or events.

The 4-way, 2-position valve is pretty neat. When you switch the position, it vents one side of the cylinder and pressurizes the other.
its a little slow and id use a scarer looking animal
that would scare the crap out of me if it was faster and made a scary noise.
sort of the point isn't it lol
god thats funny. nice instructable, i love it great awesome funny except it was a monkey not a yeti. ;)
I actually saw it working cause i live really close to occidental. It was pretty awesome. Was a bit noisy though
oops, you already mentioned those, sorry.
Neat instructable, What would be really scary is if you put leds in the eyes and made it so it would roar really loud.
You can also give the puppet an internal skeleton (armature) to hold his arms out. what pressure are you running, ~20psi? with that cylinder diameter you could really make that monkey leap out. also, ebay is a great source for cheap pneumatics, I got a 10 circuit, individually regulated, double action solenoid actuated manifold for $50.00. way bigger than i'll ever need, but it's great for this kind of stuff.
I can't quite remember the pressure, but it was probably around 30 psi. The monkey did move pretty quick, but I was mostly concerned about compressed air at too high a pressure spraying out the front from the hidden airlnes. I aimed for startling, but not dangerous.
hehe :-P<br/><br/>If I can dig up some pistons, I will definitely try to do this. But I don't know if I have them... <br/>(I know I have a compressor, so I <em>should</em> have pistons, right?)<br/>
same here
you could even cover it completely up with cloth and replace the 'yeti' with something less expensive so the cage just jolts around a bit
Awesome! I skimmed the instructable, so maybe you can't do this, but I would replace the wire with fishing line, so you can't see it.
In low light you couldn't see the wire, so it wasn't a problem.

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Bio: Eric J. Wilhelm is the founder of Instructables. He has a Ph.D. from MIT in Mechanical Engineering. Eric believes in making technology accessible through ... More »
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