Theater group DC Revels wanted a working replica of one of Leonardo da Vinci's famous machines for their annual winter show, but they only had notebook sketches from the 15th century. I worked with them to build a working, stage-ready replica that stayed true to the original design.
Part of SDU's sophomore graduation requirement was a capstone project exploring the intersection of art and science. SDU Co-Director Dr. Alan Peel suggested helping the DC Revels with their Renaissance-themed Winter Show. They wanted to turn Leonardo da Vinci's sketch of a drum that played itself when it was pulled forward into a working replica for the show, but didn't have time to build it themselves and were looking for some help. This caught my eye because it combined my interests in theater and engineering.
I started by chatting with production manager Margo Brenner and set designer Collin Bills about their requirements and how they planned to use the drum within the show. I also submitted a project plan to Dr. Peel and Dr. Miller at SDU. Luckily, I didn't need to design the entire drum myself—Leonardo had already done that for me.
Once the design was approved by Revels, I started buying materials and constructing the drum.
How the Drum Works
The core feature of the mechanical drum is that it plays a percussive pattern on itself as it's drawn forward. Da Vinci's design accomplishes this by using the forward motion of the wheels to drive dual vertical drums with a pattern of dowels that trigger spring-loaded drumsticks to strike the drum.
- We decided early in the design process to avoid using modern fasteners and attempt to build as much as we could with only techniques that would have been available in the 15th century. It's narrowly possible that da Vinci would have had awareness/access to metal screws, but the dowel-jointing system we came up with worked really well once cross-braced with twine.
- Machining the central gear from wood required lots of precise drill-pressing to keep it within the tolerances we needed to drive the central mechanism.
- The drive mechanism needed to be left unstained to prevent friction and sticking.
- Setting the trigger pegs at the proper distance and height. Our final design allowed for pegs with different heights to be moved around to program beats with different tempos and dynamics.
- Properly tensioning the drum sticks so that they had enough force to strike the drum loudly, but didn't jam up the drive mechanism.
- To accommodate turning without the need for a differential, only one wheel was attached to the mechanism.
Bill of Materials
- Bass drum: free from Revels existing inventory
- Cart wheels: $170.19
- Framing wood (2x2 pine & hardwood dowels): $83.05
- Drill bits, rope, felt, conduit, misc. fittings: $92.99
Total Cost: $346.23
24" cart wheels were sourced from the excellent online wagon wheel shop CustomWagonWheels.com. Special thanks to my dad for helping me through planning and measurements, letting me use his workshop, and drilling many of the hundreds of drill-pressed holes we needed for the drum.
The drum was finished in mid November and transported by Toyota Sienna to the Revels theater in Silver Spring. The drum was used in eight Christmas performances and seen by approximately 10,000 people.
My handoff to Revels included a care sheet detailing how to assemble the drum and perform basic maintenance; the drum also won the Beth and John Pattison Award for Creativity in College Park Scholars.
Based on my experience with the drum, I decided to pursue a second capstone project at the Library of Congress, where I completed an individual research project on Leonardo's machines. It was awesome spending time at the Library's reading room going through copies of the Codices.
At the Smithsonian
In 2014, I was invited to bring the drum to be part of a temporary exhibition on Leonardo da Vinci at the Smithsonian Air and Space Museum. I borrowed the drum back from Revels and had one night to put the drum back together and fix the mechanism for the hands-on exhibit the next day. It was really cool working in the museum after hours - Kiersten and I had the place to ourselves. I was able to get the drum back to good working order, and folks had a fun time running the drum around the upper floor of the museum.
As far as I know, the drum was destroyed after the Smithsonian exhibition, but it may be hiding in a storage closet somewhere.
If you'd like to learn more about Leonardo da Vinci and his designs for all kinds of machines (including musical instruments and the mechanical drum), I recommend Leonardo's Machines: Secrets and Inventions in the Da Vinci Codices.