Product
“The Very Hungry Caterpillar”, a mechanical model in which a caterpillar moves towards and away from an apple. Flowers, fruit, and leaves are in the background.
Procedure
Instead of starting with a story, we started with a movement. The movement that caught our attention was 114, Reciprocating Rack and Pinion.
Once we decided on this, we set out trying to recreate it. This was a lot harder than we thought – we had to make the Illustrator file for the rack, as well as altering a gear from Gear Generator to only have teeth on one side. We had to make very variations for the rack because the teeth would usually catch onto a part of the alternating part. We were able to figure out with this design that alternating teeth at the end would need to be cut to prevent the gear from catching somewhere. Once the files were made, we still had to laser cut them.
After multiple renditions of laser cut pieces, we finally found a working combination of dimensions. Next, we figured out our story. The first idea was waves at the beach, then it was a moving color wall. Eventually, we came up with our final theme: The Very Hungry Caterpillar. Once we had this, we designed a layered set of racks and pinions, including some detailed engraved and cut leaves added by Miyu. The goal was to have three rack and pinion sets, each set into a frame and positioned one in front of the other. Making the back gears that would turn move all the gears altogether was challenging as well because we realized that the rack had to move in opposite directions. This meant flipping the rack horizontally so that the cut teeth would be alternating.
The back frame was cut out of wood, and it was stained to make it looker closer to tree bark, fitting with our nature theme. The other two frames were acrylic to allow a view of the art behind them. The gears were also cut out of acrylic, but we put segments of the caterpillar, laser cut from wood and painted by Miyu, on each gear. We also vinyl cut the leaves To keep the engraved segments from getting burned, we covered the edges of each piece in masking tape while cutting.
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To stand the three frames up, we cut out triangular bases that would fit the different dimensions of the wood and acrylic bottoms and made a support for the top for more stability.
Challenges
(Sara) As tempted as I am to say that this whole project was a challenge and close this blog post out, there were some particularly difficult roadblocks. Our main problem was getting the exact dimensions of the rack and pinion. This took a lot of Illustrator adjustments, which is a major task in itself as the software is not at all intuitive. Furthermore, we had to continually adjust, print, adjust, print, etc. until it worked as intended. unless I made an assembly is Solidworks, there was no way to automatically check if the dimensions would fit together.
If I were to start this project again, I would do all of the laser cut files in Solidworks to save me the trouble of floundering about in Illustrator.
(Miyu) I think after getting the main rack and pinion to work, I struggled a lot with the back gears because I couldn’t figure out the right position for that and the rack. I would have chosen a different design if we started again or just taken out the racks in the back. I also think I spent too long adjusting the design and files in Illustrator so I would have focused less on that and making sure the whole design works. I also wasn’t sure what kind of glue to use, but Rachel helped me with what type of glue to use for acrylic to acrylic and wood to acrylic so I wish I had used the right glue initially.
Cost Analysis
- Plywood = $6/sheet
- Acrylic = $15/sheet
- Vinyl sticker = $2.20
- Contact paper = $5.99
- Spray Paint = $4.58/can
- Watercolor Paint = $7.99
- Laser cutting renting (~ 5 hour): $25 / hr = $125
- Wood Stain can = $8.78 / 4 = $2.20
- Labor (~ 67 hour) = $20/hr = $1340
Approximate Total Cost: $1,508.96
