Movement in Wood

Hi! What’s up? Everything good? Here’s a photo:

A mockup of the animation rig in plywood.
A mockup of the animation rig in plywood. Click for video.

You may remember our previous experiments motorizing these characters, with cardboard and yogurt containers. That was moderately successful, but didn’t satisfy all our requirements: we need something durable that can support any amount of weight, be positioned at a fair distance from the props, support more than one movement at a time, and be accurately replicated for multiple scenes. This prototype is not all of those things, but it’s some of them!

Our animation rig has four main parts:

  1. A rotating cam (the off-center circle) which allows us to "program" an animation—as it rotates on a motorized axel, the distance from the edge of the cam to the axel determines how far we'll move the component being controlled.
  2. A cam follower on a lever (the hinged horizontal bar above the cam) which translates the cam's rotation into up-and-down movement.
  3. A line tied to the cam follower (not pictured) that will run straight up, then back down to the floor, out into the scene to the prop that will be moved, then up the back of that prop to whatever is moving (i.e. the raccoon's balloon-giving arm).
  4. A weight hanging on the end of the lever (not pictured) which counters the force exerted by the prop line, to ensure that the lever is always pulling down slightly, to maintain contact with the cam, but adjustable so that the total force does not overload our motor.

I’ve been moving around shopping bags full of hardware, tied to various kinds of rope and twine, and clamped to different parts of the system, trying to get this thing just right. You might notice that this protoype looks extremely hacked together, and that’s because it is. The first version looked a little cleaner, but as I continued adjusting, I opted for quick over pretty. Now, I think I have a good idea for where everything needs to be placed, so I can make a new version of this that looks a lot neater and will be a bit sturdier.

A big problem has been friction in every single moving part. I waxed the cam, which made that part run smoother; I’ve tried different kinds of pulleys to direct the line to the different places it needs to go, and ran into trouble very quickly with the clothesline pulleys I bought back in October that never made it into Graveyard Swing. This week I bought skateboard bearings and a hole saw and am experimenting with building my own pulleys. They look silly, but they’re working so far and they run very nicely.

I hope to finish building Variable Stage Cam-Based Animation Rig 1.0 this weekend so that I can get back to sculpture. Zander is visiting this week (!) and it would be great if I could hand this project off to him, so he can carry it to the 95 yard line while I play with the animals.

In other news: I looked at a theater last week that will be the site for Bobby’s Birthday. I’m not telling you where it is until I’ve signed the contract, but I can tell you that Bobby’s Birthday has been pushed back to August. That’s when this place is available, and honestly this show is not going to be ready by the end of this month. What was I thinking? I’m still hoping to have most of it done by then, but now I have lots of time to polish and work on all of the little things I’ve already cut from the prdouction. That said, by the time this show goes up, I should be well into the work required for Graveyard Swing 2.

Gonna get back on the regular Wednesday schedule starting…now. Talk to you soon!