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false piston: how the hell do I make that? Answered

Hello Instructonauts, I have a bit of a problem. I need to make an object with a piston like action. This wouldn't be such a big deal if I could actually just use a piston but I can't. I need a method for creating a piston movement of a cylinder inside a tube so the device moving the piston cannot be any wider than the piston. I considered pneumatics but that would require supplies I do not have and have never worked with. Does anyone know a way to make this object?

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gr33ko (author)2009-04-03

or maybe attach the piston to a worm gear. as long as the piston isnt compressing anything or moving fluid you should be ok

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gr33ko (author)2009-04-03

Have you done any research on linear actuators? This may be your solution!

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Marcos (author)2009-03-04

Are you looking for a project idea, or do you need to build a piston like an internal combustion engine? If it's the first one, why not make a fire piston, and get a cool gadget in the process. If you don't know what they are, look 'em up. I think there is at least one instructable on how to do it. Warnining Will Robinson: it's not easy, but it will be satisfying when you succeed. Let us know what you do.

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wow-amazing (author)2009-02-17

Maybe a mouse? Or a finger!

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Goodhart (author)2008-12-26

Would the drive similar to what a locomotive uses to transfer energy from piston to wheels, work? In reverse of course...

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finfan7 (author)Goodhart2008-12-26

isn't that just another classic piston?

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Goodhart (author)finfan72008-12-26

Yes, but I thought you were concentrating on the "drive" which can be "outside the wheel" like the locomotive, or two lengths of metal slats that rotate around the outside of a pin....there are several ways to drive the piston, but I am not sure they fulfill your parameters.

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chiok (author)2008-12-26

Does it need to reciprocate or is a linear motion sufficent? Or operate automatically? A rack attached to ID of the inner tube and a pinion and motor that runs along it (forward and back motion of the motor for in and out). Or a pulley system that pulls the slide like a sash window. Does that make sense?

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finfan7 (author)chiok2008-12-26

It took me a moment to figure out what you're saying but once I did i realised a pully system might work. I have no knowledge of sash windows but if I use a modded servo for the drive I could probably set up a pully system and hide the wires/ropes inside "supports." Thanks for the aid, Chiok.

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Goodhart (author)2008-12-25

Are you saying that the cam or crankshaft driving the piston can not be longer than the width of the piston?

At this Link, the Conventional method of driving a piston is demonstrated.

The Wankel engine uses a totally different drive; essentially, it works like this picture demonstrates.

A camshaft can drive smaller pistons, without having a direct connection to them. And at this link, if you scroll down, you can compare both cam and crank movements.

If I am not understanding what you are asking for, try again to help me understand.

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finfan7 (author)Goodhart2008-12-25

I am saying that whatever method of propulsion I use on the cylinder it needs to be no wider than the cylinder itself. (Keep in mind that I am not really looking to make a true piston and within this project I don't think using one would be quite possible) I need something which will move a cylinder 6-8" long x 2-3" wide within a tube approximately the length of the cylinder in a back and forth motion. The reason I don't think a traditional pison type setup will work (if you haven't already figured it out) is that the directional motion of the piston is equal to the diameter of the rotation circle of the attach point, so a 2-3 inch wheel cannot move the cylander 6-8". I am looking for a way to move the piston back and forth that will fit completely within the tube, including power source.

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Weissensteinburg (author)finfan72008-12-25

Could you just tell us what you're making?

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