For my midterm project, I chose Mechanical Movement 131. I chose this because it had rotational and translational movement. Also, I wanted make something with a running shoe and this gear reminded me of a shoe striking the ground.

Figure 1. Mechanical Movement 131

The first step of this project was to draw the components of this system in Adobe Illustrator. At first, I had many challenges drawing the gear teeth because I didn’t know the correct angles for the gears to move smoothly. Once we got access to gear generator, I used the program to make a circle gear and cut ⅓ of the image on Illustrator for the rotating gear in my project. For the rack, I snipped one of the teeth from a circular gear and repeated it several times to place the teeth in a horizontal line. The rest of the objects were simple shapes and fairly easy to create in Illustrator. 

Next, I created a lower-fidelity prototype of the gear system out of cardboard, tape, and straws. My main focus of this prototype was the mechanical movements so I did not include the aesthetic components. A video of this prototype can be found here: IMG_4314.

Figure 2. Front (left) and side (right) view of low-fidelity prototype

To my surprise, the gear teeth of the circle gear and rack fit together very nicely on the first try. The biggest obstacle with the prototype was converting my 2D idea of the shapes to 3D. I printed multiples of some pieces, like the rack and driving wheel, to make them more sturdy and align with the other pieces. This prototype showed me that the pieces fit together nicely but some improvements would need to be made. These improvements include:

• Making the circle gear out of a very strong material because it undergoes a lot of force from the driving wheel and rack
• Adding a handle to the back of the driving wheel to make it more user-friendly
• Extending the flat pieces on the side of the rack
• Making sure no pieces of the driving wheel interfere with the circle gear when it is rotating
• Ensuring that the teeth of the rack fits snugly within the circle wheel to make it move more smoothly
• Ensure the center of the circle gear is firmly attached to the backboard
• Reducing the dimensions of every piece to 70% of the original dimensions because the prototype was too large

After adjusting the Illustrator file for the previous improvements, I printed out the pieces in high-fidelity materials. I chose to print out the circle gear in metal using the water-jet cutter to ensure the piece was strong and durable. As an aesthetic piece, I decided to print out a metal circle arrow directing the user to turn the driving circle the correct way to mimic running motion. The rest of the materials I cut with the laser cutter out of ¼ inch wood. I spray-painted the wood pieces. I chose silver for the rack to match it with the metal gear, black for the background, and navy blue and green accent colors for the decor pieces.

       

Figure 3. Various Pieces of Project

Assembling this prototype was the most challenging part of the project. This was mainly because the driving wheel would get stuck when the notch reached the bottom due to alignment issues. After lots of trial and error, I realized fitting the rack teeth into the circle gear more snugly allowed the gear to flow more smoothly. However, after I would adjust the height of the rack and get it working correctly, I would come back later in the day and the alignment would be off again. After trying a couple different ways to adjust the rack height, I realized the best option was to put black electrical tape around the bottom peg of the rack holders. This method allowed the height to be raised the small amount that was needed and maintained the height over time. A video of the final prototype can be found here: IMG_4312.

Figure 4. Front (top), Back (left) and Side (right) View of Final Prototype

Overall, I am very happy with my final design. It is very close to the initial idea I had in my head and I am proud of myself for solving several challenges that came my way in the products creation. 

For this model, the raw materials included 1 40” x 28” wood board costing $10, 1/8th of a metal board costing  $22/8 = $2.75, a hot glue gun costing $11, super glue costing $4.50 for a total of $28.25. Adobe Illustrator costs $19.99 a month. If drawing on Adobe Illustrator was a part of my job and I worked on it for 10 hours a week, 4 weeks a month (40 hours), using it for 4 hours to create the file would cost $2. This project took me a total of 15 hours. At $12 per hour, labor costs would be $180. The total cost would be $210.25.