Midterm Project: Moving Chinese Dragon
Elena Nikolaychuk and Gabby Lea
For the midterm project, students were expected to partner up to create a working mechanical model based on one of the mechanical movements featured in the 507 Mechanical Movements catalog. Gabby and Elena have united for a G.L.E.N Productions project yet again! We chose the 96th movement called the “heart cam” because it was cute. Agreeing later that this shape would result in a lot of friction that would impede movement, we chose to simplify the cams and make them circular.
Figure 1. Mechanical Movement #96.
Shifting over to planning, we brainstormed some concepts to apply our movement to. We chose to do a Chinese dragon that wiggles through the air as you spin the handle. The cams would be attached to a dowel rod supported by a box enclosure. By Gate 1, we had prepared some concept art and .svg files drawn in Inkscape.
Figure 3. Concept Sketch of Design (side view).
Figure 4. First .svg File for Gate 1.
After this checkpoint, we started making our cardboard prototype to prepare for Gate 2 of the project. Using the laser cutter and our prepared .svg files, we assembled a low-fidelity cardboard model.
Figure 5. Cardboard Prototype (low-fidelity) for Gate 2.
In this process, we realized the dragon body pieces were too big and that the supports for the body pieces were too narrow to stay properly positioned on the cams. To fix these two issues we sized down our body segments and switched over to small dowel supports with a larger base. During the Gate 2 check, our TAs suggested we try to do a press-fit for our enclosure and reminded us to incorporate acrylic into our design. Gabby and I split up to resize and edit the enclosure and body segments. We finalized our files and shifted over to cutting our cams from plywood to begin assembling our medium-high fidelity prototype.
In this transition, we tackled some post-processing techniques and refined our digital designs on the dragon’s body (head, body segments, and tail). We considered how to connect the body segments and agreed that a fishing line passed through the segments should do the trick.
Figure 6. Sanding of Dowel Supports for the Body Segments.
Figure 7. Beeswax Application for Post-Processing.
Figure 8. Finalized Dragon Body Design (tail not included originally).
Unfortunately, disaster struck over the fall recess and Gabby ended up with a concussion about a week before Gate 3. They valiantly continued their efforts in doing the digital design work from home but were unable to physically be in the OEDK for the fabrication and assembly of the medium/high fidelity prototype.
To create the press fit box housing, Gabby went to the MakerCase website and created a 5x5x12 inch box with 0.5675 inch finger joints. Because the acrylic would be a different thickness than the plywood, they created two different box files with the two thicknesses (0.1875 in for the wood and 0.125 in for the acrylic). Then, they overlapped the box pieces for the sides where there would be a wood-acrylic joint to get the correct joint depth.
Figure 9. Digital Files of Press-Fit Enclosure.
Figure 10. Digital Design of Acrylic Side Pieces with Wave.
Transitioning into gate 3, I continued cutting parts and post-processing other components as they were completed. I made a simple tail design and figured out how to attach the dragon head. It was a lot of busy work and it was all over the place. I did my best to reserve ample time for the equipment but was frequently interrupted and had failed prints and cuts. At this time I also used the vinyl cutter to cut out white waves to go on top of the wave cut-out in the acrylic sides.
Figure 11. Gluing and Sanding of Components.
After finally getting the last few critical missing components reprinted (again), I was able to move on to securing the cams onto the main dowel rod. I marked the dowel rod where the cams should be located based off of our decided measurements, making sure that the support dowels align as well. I had to add small rails to the bases of the body support dowels because the cams were sanded unevenly and I wanted to minimize the spin of these bases since they could inhibit motion.
Figure 12. Dragon Head Solution
Figure 13. Rails (added with thin dowel rods).
Figure 14. Vinyl Sticker File
The time it took to cut all of the remaining pieces on the laser cutter was a disaster. In between the laser cutters breaking down, corrupted files, equipment booking issues, and general delays– I scrambled to get everything printed and reprinted, cut, and re-cut. I didn’t take as many pictures at this time since I was running around just trying to get everything done.
I was not able to use the water jet cutter because it was unavailable at the time I was working on processing the handle. I ended up using the plasma cutter to cut out a simple metal piece with holes for the main spinning dowel rod and a small dowel handle. After plasma cutting, I used the angle grinder to shave off the resulting dross and followed that up with the sandblaster in the wet lab. After smoothing out the piece, I went outside to apply a matte clear coat.
Figure 15. Close Up of Alignment.
Figure 16. Plasma Cutting of Handle.
Cost analysis:
| 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 | |
| Steel Sheet (¼x20x20”) | $20.00 /sheet | Amazon | 2×4” Cut | $4.00 | |
| Metal Wire (100 ft) | $4.93 /roll | Home Depot | 4 Inches | $0.02 | |
| 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 (Gabby) | $19 /hr | ZipRecruiter | 2 Hours | $38.00 |
| Laser Cutting Operator (Elena) | $19 /hr | ZipRecruiter | 10 Hours | $190.00 | |
| Plasma Cutting Operator (Elena) | $15 /hr | ZipRecruiter | 1 Hour | $15.00 | |
| Vinyl Cutting Operator (Elena) | $16 /hr | ZipRecruiter | 1 Hour | $16.00 | |
| Overhead | Makerspace Access | $40 /month | The Maker Barn | 1 Month | $40.00 |
| Design | Drafting and Iterations | $348.36 | Calculated in the Table Below | 2.5 Prototypes | $348.36 |
| Total Cost | $717.70 |
Prototypes
| Cost Type | Cost | Price | Source | Quantity | Total |
| Materials (Low) | Cardboard (6×9”) | $16.99 /50 sheets | Michael’s | 10 Sheets | $3.40 |
| Hot Glue | $3.99 /bag | Michael’s | 1 Bag | $3.99 | |
| Tape | $7.98 /roll | Home Depot | 1 Roll | $7.98 | |
| Materials (Med/Hi) | Plywood (¼” 2×2 ft) | $8.99 /board | Home Depot | 1 Board | $8.99 |
| Labor | Prototyping Engineer (Gabby) | $36 /hr | ZipRecruiter | 6 Hours | $216 |
| Prototyping Engineer (Elena) | $36 /hr | ZipRecruiter | 3 Hours | $108 | |
| Total Cost | $348.36 |
To make this final assembly without the resources provided at the OEDK (outside of machine use), an estimated budget of $720 would be adequate. Combined with the prototyping cost, this total accumulates to $1,066. Makerspace access at a location like the one linked includes access to a wood shop, metal shop, and laser cutter, among other small tools we used. Since we worked on the project (both the final product and the prototypes) over a month, this estimation reflects the cost of an entire month. The cost of waste management is also included in the Makerspace fee.
Figure 17. Final Assembly of Project.
Figure 18. Proof of Clean Workspace.
The project was fairly successful overall despite the obstacles faced and the loss of an operator. The dragon moves but not as smoothly as desired. The vinyl looks great from far away but didn’t turn out smoothly because it was tricky to apply because of the small details. The fishing line idea also did not happen because I was rushing to finish at that point and wanted the parts to stay on the prototype. I ended up using wood glue to glue all of these body segments to the dowel supports. Even though I used a ruler to ensure proper spacing of the cams, there still seems to be a slight skew. This mixed with existing friction makes the dragon move a little awkwardly. Overall, it is a cute design that I put a lot of work into and I am happy to see it move. I was able to practice laser cutting skills and I felt challenged in my Illustrator/Inkscape skills that I feel I have learned a lot from. I could not use the waterjet but I will try it out sometime soon now that the equipment is up and running. I was well-supported by TAs and Lab Assistants when I encountered obstacles in the project and although it was difficult, it was a fun and rewarding project to do.
~ Thank you ~
