This past week our group worked primarily on the MS6 assignment, redesigning our most critical module (our arm). We changed the materials of some of the components to PVC pipe (white components in picture below) in order to minimize the weight of the arm while still keeping it relatively strong; it is now about 1/5 as heavy as the original design (about 4lbs reduced to about 0.8lbs). This will allow us to rotate our arm faster, whereas before it probably would have been too heavy to rotate at all. Another benefit of our redesigned arm is that it does not have near as bulky a design with large unnecessary corners sticking out in crucial areas, such as at the bottom near the scoop. It will still take up almost the entire width of the slot with a flat face pushing the balls, however, to prevent balls from getting forced (wedged) into the walls of the slot and getting stuck, making it more difficult for our arm to continue rotating.
We decided to use the square aluminum rod for the axle by rounding the ends on a lathe in order to eliminate some issues with effectively constraining the axle to the arm section. It will be inserted into a square, interference fit hole in the top of the arm section. The PVC arm section will undoubtedly be our most difficult component of this module to manufacture with the square hole in the top and flat cutout with holes on the bottom half, not to mention the precisely angled cut on the bottom that the scoop piece with be assembled flush to. The scoop section will be attached by a PVC rod 'plug' which will then be attached to the front aluminum plate and PVC arm section. (see images below)