[coreyjon]

yea, the problem using a proximity switch, is that it used magnetics, and aluminum is well...not magnetic, it is classifiea as a "non-ferrous", or "non-ferromagnetic" metal.automated can crusher is a neat idea, we had to make hydrolic can crushers for an engineering class, and bot was that fun, we could crush anything that would fit in it. Being automated, I suggest using some type of saftey, if this is a cans go in until its filled to a certain point kind of deal, have a infared beam cutting across the top, and a receiver on the other side, then in your program add a delay, so that if the infared signal was cut off, or if the time it took for the ir beam to bounce off a object changes, and it stays changed for a long enough period of time, and if you had a pair of ir sensors in the "entry tube" to the crushing bin, so that if there was something blocking the ir in the crushing bin, and no obstruction of the ir sensors in the loading tube, it could proceed to crush, if for some reason there was a obstruction in the loading tube, then it would come back with a overfilled warning, or load tube obstruction - and not run until all the conditions where met. After it crushes the cans, perhaps you could have an automatic mechanism to push the crushed cans into an adjacent holding pen/garbage can.