Using larger diameter silicone tubing means it isn't hard to fully collapse the tube for a peristaltic pump. And you always use 3 ball bearing rollers, can't just rub. A geared surplus DC motor or a stepping motor should work for this. To maintain pressure you could have a small reservoir tank. Sealed, with air inside. If you pump until it is half full, you've got 1 atmosphere of pressure. You could even rig up a few photosensors to control the speed of the motor to regulate pressure. I was thinking of a pump idea for something else that may work here: Two one way valves (those little rubber ones you can get from a pet store for aquariums) rigged to a cavity. One wall of the cavity is a rubber membrane with a small woofer sealed to it. Not -quite- airtight so barometric changes don't bottom out the woofer. Experiment with a signal generator and find the best pumping frequency when it is pumping fluid. No idea how scalable that is or if it would provide sufficient flow/pressure. Maybe the outlet oneway valve could be exposed and it would spray out of that with sufficient flow (I'm talking about the ones that look like a flattened baby bottle nipple). Since the woofer has a back, too, potentially you could make a doublesided pump. Otherwise all that energy just goes into making your workshop noisy. Then you could seal the woofer in completely as barometric changes would make no difference, and rely on slow diffusion through the cone to keep pressure equalized across the woofer. There, I just gave away a good idea I probably should have kept to myself and developed, and offered for sale. :'/ Steve Greenfield
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Re: pump for spray etching
2003-10-01 by Steve
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