Anyone familiar with the musical Crazy For You knows it contains a number of trick props. One particular tricky bit involves a cuckoo clock which “cuckoos” during a scene. A few moments later, a cowboy shoots it and it “explodes." The challenge is to come up with a way that it can not only cuckoo and explode on cue, but for it to be easily reset for the next performance.
The design of the set for the particular production I was working on allowed for a crew member to operate the clock from behind. This allowed me to design a mechanism that could be operated or triggered by hand, thus simplifying a great number of details. I was imagining some sort of spring-loaded mechanism (sort of like a mouse trap) where a spring held in tension would suddenly be released when a pin was pulled, allowing various parts of the clock to pop out in a comical fashion. At the end of the scene, the parts could simply be pulled back together and the pin placed back in to make it ready to go again.
Of course, having the idea and making it a reality are two different things. Working out the mechanics of the various pivot points, hinges or other moving parts can be a nightmare to design. Even if you figure it out on paper, the properties of the materials may introduce unforeseen problems. You may pull the pin and find out the mechanism gets caught up, or cannot move the way you want it to. You might discover you want to switch to a longer spring, but you built all the other parts to only fit a shorter one. You then have to take it all apart, fabricate more tiny parts by hand, and put it back together. I wanted a better way to rapidly prototype different ideas and configurations without having to fabricate or machine dozens of custom parts.
So I got an Erector Set. For those unfamiliar, an Erector Set (known as Meccano outside of the US) contains numerous metal plates and brackets with evenly spaced holes. Combined with nuts and bolts, they allow you to make any number of mini mechanical devices, such as cranes, bridges and trucks. Using an Erector Set allowed me to quickly assemble the “guts” of my clock for testing, without needing to fabricate parts or buy specialized hardware. If I needed to move a pivot point, I could simply move the bolt to a neighboring hole. If I needed a part to be longer, I could simply switch it out for a longer metal piece from my collection of parts.
In this way, I could experiment with how the clock exploded and reassembled without having to spend time building all the little bits and pieces to make it work. Building the “guts” like this also provided sparks of inspiration as I watched the mechanism in action; for instance, I discovered I could use the arm that pushed the front open to also shoot the cuckoo through his little door, which led to a much funnier effect.