For this project we were tasked to create a working mechanical model. We decided to make a piano player with 6 arms. The idea was based on this image:
Initial Adobe Illustrator Files:
The initial idea was 2 sets of cams and cam followers inside a box. They would be connected by a row of gears running down the outside. The top cams would be supported by the top panel, and there would be a middle panel supporting the bottom cams, which would take a right angle out the front of the box. The pianists arms would be attached to these bottom cams and move up and down with them. We used gear generator to make the gears and MakerCase to make a box with dividers, which we adjusted to be fully closed.
Initial Files: Cardboard, Cardboard2
Medium Fidelity Prototype:
We used our mid-fidelity prototype to test a couple of key features: the gears and the cam systems. From initial testing we determined that the cams needed to have panels on the bottom so the cam pushed into the bottom of the follower instead of into the side. We weren’t able to properly test the gears, as the cardboard has holes in the side that the gear teeth got caught in. However, we were able to turn it enough to make it apparent that this was the main problem, and that it would be solved when they were made with wood.
Final Prototype:
We made a few adjustments and additions to the final prototype. We initially had 2 sizes of cams for the bottom set, but we found they did not have enough space to fully turn. As such, we replaced them with the smaller ones. We actually repurposed one of the larger cams for the crank. For the middle supporting piece, we moved the holes such that the cam followers would be up against the front panel. This made it so most of them were unable to tilt, and also made it so the cams would push up against the bottom of the cams even without adding panels. A couple of the cam followers tilted forward through the holes in the front panel, so we made a few brackets to trap them against the front panel.
This did create a new issue however – because the cam followers were now further away from the cams, the bottom cams had to be rotating clockwise to lift them. This was inconvenient as the top set of cams had to be rotating counterclockwise, but our gear layout made both sets rotate in the same direction. To fix this, we made the top cam followers very large Ls so the cams would push against them properly. We also added a second supporting piece to hold them straight.
After these fixes, the model was working and just needed decoration. We spray painted the prototype black, except for the top cams, which we made white so we could add musical note vinyl stickers. We added the piano player, which we gave arms made of pipe cleaners and a cotton body. We made the very top gear connected to the crank out of waterjet cut metal.
This is the final Adobe Illustrator file: Final Box
This is the Adobe Illustrator file for the piano layers: Piano Keys w Holes
This is the final prototype:
Overall, the project came out very well. While not very smooth, the model functions without error. The pianist is rather low fidelity, but it looks like a spider which fits the theme very well.
