Rube Goldberg Progress Report

As you may remember, the kids and I are spending a large chunk of our school year building a Rube Goldberg machine. For those of you just joining us, I’ll give you the nutshell story so far (you can also click on the Rube Goldberg category at the end of this post, and it should pull up all my related previous posts).

We began by studying physics, simple machines, and Newton’s laws all while working through the Lego WeDo robotics kit. Then Ian signed up for the Rube Goldberg project with his Science Olympiad group at the middle school, and I thought: I want in on that. So we decided to build one at home as well.

To start the Rube Goldberg project, we began with youtube video research, sketching plans on our hallway wall, and building smaller projects to get our feet wet. When we got brave enough, we picked one of the kid’s brainstormed components, which happened to be Eva’s Harry Potter themed falling pendulum. She wants to make her Harry Potter broomstick “fly” back and forth and down; at the end, it will knock something else over starting a new series of events.

There a couple of things you should know before I share our progress with you.

1) Despite my most fervent efforts, I can find no resources that teach how to build a Rube Goldberg machine, or how to do this in a classroom setting. This is probably due to the fact that the very essence of these machines is their uniqueness. It’s really whatever you come up with. But I can’t find resources to even help us get started. I’ve heard to begin by building the beginning and end components, but that wasn’t working for us. So we’re starting in the middle and moving both backward and forward. We’re making this up as we go here.

2) I am in no way an engineer or handy-woman. Once early in our marriage, Jamie and I knocked out some wet sheet rock in the top of a tiny closet, looking for the offending leak. What we found was a distressing lack of pipes. Perplexed, we went upstairs only to discover a leaky water bottle stored in the closet directly above. The angst and agony we went through to replace the unnecessarily removed sheet rock served as an early relationship test. We made it out alive, but we now try to limit our household projects to stay within our limited abilities.

3) I’ve never studied physics.

4) We have no working budget.

Now that I’ve said all that, I’m sure you are reading with the appropriate non-mocking attitude that I strongly desire. I’m going to tell you our story through pictures.

Eva's sketch of her Harry Potter broomstick falling pendulum

This is what we started with. We decided to use plywood to make the main face of the structure. I raided my garage and found quite a few handy items, namely all the wood we needed. The plywood is left over from a playhouse we built several years ago. The 2x4s we found to make the stand were old concrete frames that a contractor left here after laying in a patio for us.

The kids sketched out the design on the plywood, and I suggested a sweeping pattern to enhance the broom’s sweeping motion (pun intended). I used a jigsaw to cut out their pattern.

Cutting out the sketched pattern

I cut our stand down to size, and the we put it all together in the basement.

Ian nails the plywood to the stand

Once the kids put the feet on, they could stand the whole thing up:

The erected pendulum structure

Next the kids took an old dowel, tied the broom to one end, and a bucket full of weights to the other. Old margarine lids served as the “washers” to keep the dowel from sliding. Here’s Eva adding the counterweights to the bucket:

Eva balances out the counterweight bucket

And here’s Falling Pendulum Version 1:

The falling pendulum, ready for its first trial

Here’s what happened when they tried it out:

The result of the first falling pendulum trial

As you can see, it was a total train wreck. The margarine lids had no ability whatsoever to keep the dowel from sliding, and the broom spun in circles, crashing in to the frame. We had issues to resolve, so it was off to the hardware store to see what we could find!

Hardware store bounty!

The washers and pins replaced the margarine lids. Here’s the new look:

Much fancier than the margarine lids. And more effective.

But the next trial didn’t do much better. Turns out that the washers, big though they are, weren’t big enough to stay on the track at the peak/turns. They fell right out. Eva tried to fix this by hot gluing some yogurt lid pieces to the corners, but that didn’t end up working, because the washers tended to slip up inside anyway. To make a more effective correction, Ian took the wood I had cut out of the plywood piece and had me hacksaw off some pieces that they hot-glued back into the slot.

Eva hot glues on the plastic frame adjustments

And here’s the revised revision:

Eva glues in scrap wood to fill in the gaps

The next issue we tackled was the broom-on-rope-swingy-issue. We needed it to swing back and forth, not twist. Ian grabbed more scrap wood out of the garage, and had me drill some holes to make a non twisty-pendulum arm.

Ian secures the broom to the pendulum bar

We were so proud of ourselves! We had accomplished so much and felt pretty good about how the next trial was going to turn out. And that was our mistake. For alas, when we tried it again, my cleverly advised sweep-up track proved too much; the broom never made it past the first level. It just sat there, staring at us, mocking a bit, I think.

And again:

I didn’t excuse “class” until the kids identified the next revision. They decided to remove the sweep cut, which means I need to cut another piece of plywood (thankfully, I have one more in the garage). We’ll try a straight zig-zag pattern instead.

I’m loving all the problem solving this project is providing. When you don’t know what you’re doing, then you just have to figure it out.

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