Mechanics (extra 3rd prototype): Wooden Wave

Wooden Wave 

I liked that my 2 mechanics prototypes were complementary (Harmonograph and Spirograph), since I think interaction with both might enhance the users understanding of the relationship between gear ratios and enhance the overall experience. However, since they were so similar in concept, I wanted to make a third mechanics prototype that was entirely different. I didn't bring it to the Exploratorium on the day of the mechanics exhibits, because the pieces on the dowel came loose, but I want to share it on the blog:

Project in a Nutshell: This is a prototype that has two hand cranks, and these cranks translate into a wave motion of wood, similar to Britt's Sine Wave Generator and Winnie's Mirror Ripples (all three use the same mechanism with dowels and ovals to create the wave motion.) Since there are two parallel hand cranks, the user can turn them in unison or apart, to see the effects of these motions on the wooden wave above. 

Concept and Ideal Interaction: The initial inspiration definitely stemmed off of the automata activities we did in the Tinkering lab, as I think Winnie and Britt were inspired too. I originally wanted to show a sine wave being generated from the motion too, but I wanted a second degree of freedom where the user could experiment with the waveform. Thus I have two cranks that I hoped could create more complex motions of the wood's movement as the user turns the cranks at different rates or different offsets. I have a video of my attempt to test my prototype. I realized there was too much friction, and near the end the wooden planks all fall to one side... I'd imagine with acrylic or a frictionless environment, the movement would be quite elegant (unlike this video):

Problems and Improvements: As you may notice from the video, there were several problems with this prototype. First, I forgot an important lesson taken from our time in the Tinkering lab: the power of friction. We discovered that we didn't even need gears to have foam ovals rotate each other, because of the friction, which was a neat surprise! However, I forget that friction can play against you too. I wanted the wooden planks on top of the dowel and circles to slip back and forth, thus exhibiting up and down motion, but not side to side motion. However, because of the strong friction between wood on wood, the turning of the dowels created a lot of sideways force that would cause the planks to go shooting left and right. I eventually tried to solve for this problem by using two sheets of acrylic, or in the video, two books to contain the planks in place. However, next time using something with less friction like acrylic would be a better idea and would better exhibit the ideal motion I had intended. Currently as it stands, the wooden wave is a bit hard to use since there is so much friction causing the planks to pop up.

Other things of note: Not directly related to Wooden Wave, but related to Tinkering Lab and mechanics, I mentioned I made a wire boxing kangaroo in the Tinkering lab, and since Sebastian encouraged that we post the end results here, I'll post a video (I already posted an image in a previous blog post.) While I liked the extra-long arms, I ultimately ended up snipping the arms shorter because the long arms were causing the motion to be a bit jerky: