For the adjusted midterm project, we decided to re-fabricate and assemble Gabby and Elena’s original midterm project of a dragon flying over the waves. This project used a series of 8 cams to turn rotational motion into translational motion. A hand crank on the side of the box rotates, causing the segmented dragon body to move up and down. Gabby already had the digital files ready from the midterm, so we just had to prepare the parts and assemble them.
here is the final product in motion!
The first step was to utilize the epilog pro laser cutter to print out the housing, cams, and dragon body on plywood and acrylic. We have practiced working with the laser cutter quite a few times so this process was easy, save for the time we had to use 5 weights because the sole piece of unused plywood in the OEDK was warped into a parabola. Gabby’s files were made with the Epilog M2’s settings in mind, so the kerf compensation wasn’t large enough, meaning the finger joints on the housing were slightly loose. Unfortunately, both the plasma and waterjet cutters in the OEDK were down for the week we worked on fabrication, so we had to use laser cut wood for the hand crank, which was originally going to be steel.
We used the vinyl cutter to create accents for the acrylic waves. The first time around was not a success- the stickers themselves were a little too big and oriented the wrong direction. The ones we placed on the acrylic were of poor quality so we re-cut at 90% scale, taking care to remove solely the necessary pieces before application.
Gabby cut a 0.5” dowel to about 11 inches in length and cut 8 pieces of 3/16” dowel to 6 inches in length using a scroll saw. We then sanded all the cut edges smooth and covered the wood in a layer of beeswax to protect it and add to the smoothness of the surface.
We used wood glue coupled with clamps to ensure a tight bond between the layered cam and dragon body pieces. It took some patience to use wood glue for the pieces that needed to be attached to the dowel as they could not be clamped down. Gabby set up a jig using two versions of the top part of the box to make sure the dowels were straight. They used a similar method to attach the circular cams onto the center dowel rod, propping up the rod on the two ends of the box and gluing the cams at different degrees of rotation. We added small pieces of skewers to the base of the dowel rods that would touch the cams so they would not shift side to side or rotate.
After the layers of the body pieces were glued together, we used small pieces of fishing line to attach each segment together. This would ensure that each piece could pivot on the dowel rods while still moving as a cohesive, giving the body a more-snakelike feel.
One all the components were assembled, we put together the whole mechanism. We put together the wooden sides and box bottom, then inserted the center rod that held the cams into the cut out side holes. We glued on wooden end caps and rings to prevent it from shifting while it rotated, and glued on the crank at the end. Then we placed each smaller dowel in its respective hole in the top of the box, then lined them up on top of the cams. Once the dowels were straight, we added the body pieces on top of each dowel. We finished adding the acrylic sides, gluing the housing pieces together, and clamping them.
Here is our workspace after cleaning up.
| Cost Type | Cost | Price | Source | Quantity | Total |
|---|---|---|---|---|---|
| Materials | Plywood (¼” 2×2 ft) | $8.99 /board | Home Depot | 1 Board | $8.99 |
| Acrylic (12×20”) | $31.99 /sheet | Michael’s | 1 Sheet | $31.99 | |
| Wood Glue | $3.97 /bottle | Home Depot | 1 Bottle | $3.97 | |
| 48 in. Dowel (½”) | $2.18 /rod | Home Depot | 1/2 Rod | $1.09 | |
| 48 in. Dowel (5/16”) | $1.14 /rod | Home Depot | 1 Rod | $1.14 | |
| White Vinyl (12×48”) | $6.99 /roll | Michael’s | 1/2 Roll | $3.50 | |
| Transfer Tape | $5.99 /roll | Michael’s | 1/2 Roll | $3.00 | |
| Fishing Line | $10.99 /125 yds | Amazon | 1 yd | $0.09 | |
| Beeswax and Orange Oil | $9.98 /bottle | Home Depot | 1 Bottle | $9.98 | |
| Assorted Grit Sandpaper | $7.99 /36 sheets | Amazon | 12 Sheets | $2.66 | |
| Labor | Laser Cutting Operator (Ayaan) | $19 /hr | ZipRecruiter | 2 Hours | $38.00 |
| Laser Cutting Operator (Gabby) | $19 /hr | ZipRecruiter | 1 Hour | $19.00 | |
| Woodworking Operator (Combined) | $19.40 /hr | US Bureau of Labor Statistics | 10 Hours | $194.00 | |
| Vinyl Cutting Operator (Ayaan) | $16 /hr | ZipRecruiter | 1 Hour | $16.00 | |
| Overhead | Makerspace Access | $40 /month | The Maker Barn | 1 Month | $40.00 |
| Total Cost | $373.41 |
This cost analysis does not include the cost of a prototyping engineer because the mechanical model was assembled based on files Gabby and Elena had already prepared. As always, the largest proportion of the cost comes from labor.
