Manufacturing & Assembly - WG

To construct our mechanism we primarily used the laser cutter on plywood and we 3D printed end caps and spacers. Our mechanism is primarily made of wood, both ¼” and ⅛” plywood, and wooden dowels. We purchased a wooden mannequin man and bearings for our rotating shafts. For our gear train, we used ⅛” acrylic that we cut on the laser cutter. 

The most complex part of our assembly was the camshaft. In order to manufacture the shaft, we needed to ensure that the offset was correct and equally spaced. We used a wooden dowel and laser cut all of the cams out of ¼” plywood. To adhere them to the shaft, we 3D printed a template that would align the disks to the shaft with the correct angle. We used gorilla glue to fix them to the shaft (Note, we used gorilla glue for the entire assembly). 

In our first prototype, our waves did not fully go around the entire circle of the cam. We did this to reduce rubbing friction of wood on wood. However we immediately saw once we assembled it that the waves did not stay on the cam, they just rotated at the back slot instead of sliding along it. To fix this, we made the wave go all the way around. In both versions, we used 1/16” acrylic flanges glued onto both sides of each wave to fully capture the follower to the cam. While this method was effective, it was difficult to assemble. Because we had to assemble the camshaft first, we had to glue the capture plates onto one wave at a time after they were already placed around the cam. 

We mounted the servo to the side plate and mounted our gear train on this face. Each gear needed to spin so we used the same bearings and small dowels with the gears glued onto the dowel. To capture these shafts and the shafts in the wave generator, we used 3D printed end caps and a small screw that we screwed into the end of the shaft. 

Once we had our final prototype assembled, we had a major issue: the cam shaft was binding extremely badly. We isolated the problem to be that the cams had a slight cock to them when we glued them on and the faces of the disks were not perfectly parallel. Because the waves were clamped around the faces of the disks, each wave was slightly askew. It caused the mechanism to bind because there were spacers at the back shaft that restricted wayward motion. By removing the spacers, the mechanism was free to rotate because the back of the waves were allowed to move side to side along its shaft. 

Final Prototype Top View.mp4

If we were to redo the assembly, we would most definitely 3D print our camshaft and create a modular interlocking system so we could print each segment of the camshaft for however many waves we want. We originally considered 3D printing the shaft but we decided against it as it would take a much longer time to manufacture.