Image 4: Measurements… pt 1

We did even more math by laying everything out on a piece of paper to scale to ensure it would fit correctly. Once we had figured out where each part would go and how big the entire assembly would be, we started designing our parts. We started by sketching parts in Onshape (a CAD software that can make dxfs) and Adobe Illustrator and finding files online to edit. Once we had our files ready, we cut our first prototype out of cardboard.

This was our low fidelity prototype. It fit together pretty well, but there were some issues that seemed to arise simply from the fact that our model was made out of cardboard. For one, the cams and followers didn’t really move.

Image 5: Cardboard Bonzo

The gears did not mesh either. The good part was that everything fit together as intended. The dowels fit nicely into the holes, the entire assembly was the right size, and it seemed that we were well on our way to having a working model soon.

Image 6: Cardboard Mechanisms

Once we had our cardboard model done and we had done our gate 2 check in, we started testing the fit of wood parts and cutting our wood pieces.

Medium fidelity prototype

Once we had all of our pieces cut out, the next step of assembly. Though in this round of cutting we tried to account for certain problems with our low fidelity, we still had to test the mechanisms. The switch to medium fidelity involved going from cardboard to wood and metal. At this point, me and my partner split, with one of use focused on laser cutting, while the other focused on water jet cutting.

Image 7: First lasercut pieces

Image 8: First waterjet gear

Before we even starting putting the thing together, we already started to run into some problems. For starters, the original laser cut for the followers was a simple rectangle, however, we found that this design had a very difficult time following the cam and we switched over to a hammer head follower to attempt to get better glide from the follower.

Image 9: New followers, cams, and metal gear

Additionally, miscommunication on sizing for our gears, along with just some problems water jet cutting lead to us having to water jet the same gears multiple times. The first round of gears were too small, and then we had continuous problems getting the center hole to cut on the gears as well. This caused us to only have one working gear by the end of the process instead of two due to time constrains. However, this likely had unintentional benefits to our design, as the heavier metal gear that we made attached to our crank made turning the other wooden gear very easy, and its thicker size made alignment not a problem.

Once we edited both the followers and had the proper gears, we started to assemble the project. This is where we would run into our last and most challenging problem, the cams didn’t work as intended. When we originally designed the cams, we attempted to make them as big as possible to allow for Bonzo’s arms to move as much as possible. However, in doing this, we made it impossible for the follower to work as intended because the cam was to steep for our follower to go over. We say this like it was easy to find out, but it took a lot of different designs and attempted solutions to narrow down this problem. We tried sanding and things like WD40 on our cams, then tried a different design by making the cams straight to replace the wide curve that had the same height, eventually landing on a smaller cam design the finally allowed our followers to work as intended. With this our problems were fixed and we began our final assembly of the project.

Image 10: Cam iteration

High Fidelity Prototype

Once we had all our necessary parts cut and put together, we took everything apart to begin final construction. We split up so one of us was working on decorative elements while the other focused on final assembly. For decorative elements, we wanted to make the drummer look a bit more exciting than just wooden, so we painted him with acrylic paint. While we did disassemble our model slightly, we didn’t take apart the main components of the man and his body, as putting them back together with paint on them would not have been easy. This caused our paint to be a little uneven, but it really gives him a lot more personality. We could not find any wooden balls for his head, so we used a styrofoam ball that we painted.

Image 11: Vinyl sticker

Next, to make his drums cooler, we used our vinyl sticker to put a design on the kick drum like most bands do. We also waterjet a simple circle with a hole to create a cymbal for his drum set. This made the set feel more complete, and it also makes a nice sound when his drumstick hits the metal.

On the assembly side of things, we started by sanding down the pieces of our project, including laser cut pieces, dowels, and our mechanical components. We also sandblasted the gear to give it a cleaner look. While sanding, we cut out our nameplate and a thick piece of wood to use as a base. I think this base makes our model much more steady and gives it a nice look. We would have loved to also incorporate some decorative components and further post processing into the base of our model, but we were concerned that with the time it would take for any stain or paint to dry fully, we would not finish assembling our project. We used a bit of wood glue to keep our base box together, and then assembled the mechanical components in place. Once the box was assembled and our bearings and dowels were in place, we brought back our newly painted Bonzo and attached the top of the box. Our model was complete! Here is a of video Bonzo drumming right after we completed him.