I originally has hoped to design a two part system – the first part being a little paper “Mario” figurine that jumped up and down, and the second part being a little mario level background that scrolled behind it. I imagined that the mario figurine would move up and down on a cam, and the level background would scroll behind it on a friction tread. This was slightly ambitious – I’d never really built my own gear system in my life (save for Lego), and for this I decided to create my own gear, tread and cam system from scratch using a laser cutter – but I thought it’d be worth a shot.
After much cutting, re-cutting, hammering, unhammering, rehammering, drilling, aligning, taping, untaping…you get the picture…I wound up having all of the physical pieces in place. However, I realized that my initial idea of how a cam worked was slightly off – a cam only pushes something up and down if that item is being pushed onto the cam by gravity and held straight in place somehow. I understood this fact, but failed to realized that the up and down motion is not something that could easily happen *in front of* the tread system (that is, in three dimensions) – which is what would have been necessary for the effect to work.
At this point, I’d plowed quite a bit of time into the thing – and in the two dimensions the gears worked well in, was only left with a functional tread system and a spare, wobbly gear. I lamented my fate for a bit until I talked with Cheng, who noted that the wobbly gear actually gave the rubber band a jerky effect. I’d been struggling to get the rubber band to move consistently smoothly on the tread for a while – but she suggested I take the opposite approach, and turn that occasional jerkiness into an aspect of the intended movement. Which is how I wound up turning my Mario scene into a frog “hopping” scene. 🙂 The entire thing is hand-powered; I had planned to run off of a single motor but
having to secure the motor in a way that kept the motor gear both flush and able to turn freely was becoming an exercise in futility.
So, after much ado, a frog hopping: