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Wooden PistonConcept:Inspired by the motion of slugs, I decided to design and construct a linear hydraulic system. The majority of the pieces would be made from hardwoods like Oak, and the tubing would be made from pure natural latex rubber.Design:The system uses two pistons that are slaved to each other. On a regular piston, set to control itself, there is a dead zone on the mechanical valve where it cuts off both intake and exhaust, essentially locking the piston in place and system failure. The initial design called for a single mechanically actuated piston, but simulations revealed that the system would lock up, as expected.This problem was compensated for by using dual pistons. By running the feed hoses to opposite ports (I.E. Top-feed of piston 1 and bottom feed of piston 2, or top-feed of piston 2 and bottom feed of piston 1), the pistons control each other. You only need to continuously feed the two pistons in order for them to continue running, and by capturing the motion of one piston you can get continuous repeating motion. Assembly:The piston design would’ve been simple to assemble in an adequate machine shop. However, the construction of the piston hit a snag when all campus machine shops refused to handle wood. I was left utilizing home-built machines, like a converted drill press that became a milling machine. While the pieces turned out well and looked like those in the drawings, the measurements were slightly off which resulted in poor fits on some pieces. Other components just couldn’t be made from woods, such as the actuator bars that snapped off when utilized.The project completion time also ran much longer than expected. My original predictions of 2.5 hours were way off, and actual completion time ran closer to 10 hours. The project also went through a redesign in the middle of it, when it had to be made an 8th of its initial size. The new pistons, while they went together faster, were harder to measure accurately and so machining was difficult. Results:In a nutshell, the piston was a failure. It didn’t blow every gasket and leak from every seam, but hose seals began to erode, not to mention the fuel caused the wood to expand and lock the entire system up to the point that parts will need to be drilled out of their holes. Definitely not the success I’d hoped for, and not even a success at all. However, with proper tools and more time, I believe the project could work. Unfortunately, I could not produce the results I had predicted.Adam Cohen, 2Train Robotics |
  Complete Piston Piston Model   Piston Model 2 Third Piston Model |