Our mechanism went through several progressive stages of design with each new stage seeing improvement over the last. The structure of the mechanism was supported by a square base with an arm consisting of two aluminum strips both of which were bent. The aluminum strips of the base were also bent. The arm was attached to the base through a series of triangle truss connections, and it went through the larger of the two windows. Our servo was attached to the end of our arm which left it about two inches from the weight. We used a lever arm with a counter weight as our lifting mechanism. The servo provided the torque to twist the lever arm to raise the weight. The extra weight of our counter weight greatly strengthened the lifting power of our lever arm.
PredictionsWith our calculated torque of 42 oz in, a 2 in. lever arm between the motor and weight, a 6 oz. counterweight, and an estimated rotation of 75 degrees, we estimated that the crane would lift the 1 pound weight 2.75 inches. Due mostly to lever arm deflection, we only managed a raise of 2 inches.
Unique FeaturesThrough a significant amount of trial and error, and progressing through 3 different iterations, we learned a significant amount of helpful building practices. First and foremost, bending the aluminum strips greatly increased the structural integrity, so we utilized bent strips at every available position. Also, after several failed lifts, we attempted a counterweight to balance the torque of the 1 pound weight.
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