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For the bucket, we knew it had to turn 180 degrees at the end of its path, then quickly reset to its starting position for the next sweep. We first found a complex 8-bar mechanism that would achieve a complex translation and rotation motion, but later simplified it to a simple 6-bar half-rotation motion with a quick return. This allowed us to cut fewer links, minimized our chance of error in joint motion, and minimized the space needed to offset each link. The overlapping motions can be seen running below simultaneously (if the image is not moving, click the image to run the animation).
Once we had our desired motion for each mechanism on Linkage, we noted the ratios of the lengths of each link in the mechanism with respect to the length of the sweeping motion so we could scale it to any size we wanted. Our limiting factor was the size of our bearings, which were 22mm outer diameter and 8mm inner diameter. With this in mind, we knew the smallest link we could make was 36 mm in length from edge to edge, including a 5mm buffer for the wood to surround the bearings and axle holes.
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