For our midterm project, we were tasked with bringing a movement from 507 Mechanical Movements to life. I chose to extend my work from my 2D Drawing project (movement #222) into a larger piece. My rationale for this is that even after working on this movement for a week earlier in the semester, I was still not sure quite how it works.

 

At this point, I will note that this project was done in partners. M partner chose Movement #144 (pictured to the left). In the end, we ended up subdividing the work so that each of us was basically working on one of the mechanisms. Thus, outside of this paragraph, this blog post is entirely about Movement #222.

 

I started off with the prototype I built during the 2D drawing project. It worked surprisingly well given the almost-zero thought and effort put into it. Here is a picture from last time. The arms are clearly too long and the entire prototype is much too small (it measures ~4 inches across). It also needed a better system than nails to attach the gears to the backboard, to each other, and to the arms.

Prototype 1: Low Fidelity

I brought the knowledge from previous work into the design phase, where I made my first prototype. My goal here was to experiment with where and what types of holes the gears needed to have in order for the axles to work properly. Some axles need to drive rotation in gears, whereas some others should allow the gear to rotate freely. I choose to use a dowel system to create the axles, with 1/4” dowels as the main axles and 1/8″ axles driven through them to drive gears and keep the axles in place.

I took the opportunity with this prototype to experiment with locations of holes on the backboard as well as on the gear that spins off-center. I wanted to maximize the movement of the middle gear while keeping the motion smooth. As shown above, I ended up settling on keeping the gears at the top of the backboard with the hole relatively close to the center. Otherwise, the movement would get stuck in certain places or gears would run into each other.

This prototype also led me to other realizations: I needed to add a washer to the right-most gear so the arm wouldn’t get bent, I needed to add a gear to drive the entire system, I needed to come up with a mechanism for the base, and I needed to make the entire thing a lot bigger. I also realized that the motion of the gears reminds me of an arm moving around, so I decided to add an arm to the mechanism so the entire thing would be waving an arm.

Prototype Attempt #2:

I won’t discus this in length because it was a failure that I did not learn a lot from. My second attempt at a prototype was to enlarge it and create a base. I scaled the center holes up so that the center dowels would be 1/2″ and the pins 1/4″. Combined with that I made the prototype WAY too big, I chalked this up as a failure and decided to go back to designing.

 

Prototype #3

After the big embarrassment that was prototype 2,  I went back to Illustrator with one thing on my mind– redemption. I wanted to be as analytical as possible in figuring out the positioning of gears and my design overall so that this could be my final prototype. I decided a good way to do this would be to draw phase diagrams of what the mechanism looks like at each stage of movement. This is especially helpful with the off-center gear which has some funky movements.

I also organized my designing modularly, so that each piece would get the attention it deserved. Finally, I pulled a Clipart picture of an arm from the internet and used Live Trace to turn it into vector form. My intention was to cut this piece out of metal for the final prototype but I did it in wood first to make sure it would work. When it came time to actually produce the metal piece, though, the plasma cutter was broken. Thus, this wood piece was in the final prototype.

This prototype, after laser cutting and assembly, worked like a charm. Here’s a GIF to prove it:

 

Finishing:

For finishing, I decided I wanted the arm to stick out the most. Thus, I spray painted it with two coats of bright pink (as if it spent a long day at the beach and got a severe sunburn) and followed that with a coat of glow-in dark spray paint. Finally, I finished the gears and gear arms with a dark brown lacquer and coated the backboard and base with beeswax to bring out the grain of the wood.

I then spent several hours cutting and drilling into dowels for the final assembly, which also included a crank to move the bottom gear. The final product, which I am pretty proud of, is below.

Overall, I learned a lot form this project. It was different from design projects I’ve done in the past which were more about producing a good-enough version of something advanced. This one allowed me to push myself to make the best possible version of something relatively simple. Thus, it extended me to learn and practice a different set of skills.