Jump The Moon - Crayon Melting Art Tray
Team: Kaden Forster, Benjamin Merrell, Adam Kimball, Sage Patten, David Spillman and Addi Thresher
Project Description
Jump the Moon is a non-profit organization dedicated to making art accessible to everyone, especially people with disabilities. Jump the Moon have previously partnered with the USU Engineering department to develop inclusive art tools.
Our project focuses on designing a heat tray that melts crayons while a user draws, creating a watercolor-like effect. Jump the Moon currently uses old food warming trays for this purpose, but these are inconsistent, unsafe, difficult to use, and not suitable for manufacturing. Our team's task was to develop a safer, more reliable crayon melting tray that better meets their needs.
Design/Systems
1. Body
The border and structure of each tray is 3D printed from PETG plastic with a rigid hardboard bottom plate and plastic feet (Figure 1).
2. Heating Element
The drawing surface is made of A36/1008 stainless steel, heated underneath by resistive nichrome wire held in a silicone insulation (Figure 2).
3. Electronics
The heating surface is controlled by code on a raspberry pico. The temperature is monitored by thermistors. A push button will begin heating the plate (Figure 3).
4. Accessories
Each tray includes a paper scraper and crayon holders, which can be stored in the lid. To secure a piece of paper, the small tray has a removable tray, and the large tray has magnets (Figure 4).
Table 1: Performance/Requirements
| Requirement | Prototype A (Large) | Prototype B (Small) | ||
|---|---|---|---|---|
| Threshold | Performance | Threshold | Performance | |
| Heat Bed Area | 12" - 18" Square | 15" square | 8.5" X 11" - 10.5" X 13" | 10" X 12.5" |
| Head Bed Operating Temp; Final Production Cost | 130°F - 140°F < $80 | 130°F - 140°F $68.89 | 130°F - 140°F < $60 | 130°F - 140°F $51.75 |
| Tray Height | < 4" | 2" | < 4" | 2.25" |
| Time to Ideal Temp | < 180 s | < 180 s | ||
| Power Cord Length | 5' - 8' | 4' | 5' - 8' | 4' |
| Border Height | 0.15" - 0.75" | 0.2 | 0.45" - 0.75" | 0.45 |
| Tray Weight | < 5 lbs | 6 lbs 13 oz | < 5 lbs | 3 lbs 11 oz |
| Min Sensor to Top Height | 2.5' | ~ 3' | 2.5' | ~ 3' |
Analysis/Testing
To confirm the uniformity of the heating surface, this team powered the tray and took temperature measurements of various points on the surface. It was determined that the heating uniformity and magnitude of the surface temperature was sufficient.
The prototype version of the small tray was dropped from chest height and took damage to the body structure. The design was updated with more rigid connections for the final small tray.
Conclusion
We learned the value of design simplicity—whenever we had to make a decision, the simplest design consistently proved to be the best choice. We also came to appreciate how challenging it is to meet all the project requirements, as we were constantly revising and adjusting to meet them.
Overall, we had a great experience, and each of us feels more confident in our engineering abilities.
Recommended Future Work
This design was constrained in part by the manufacturing choice of 3D printing. For larger batches of trays, it would be more cost effective for mass production to use injection molding or a similar process to create the plastic parts shown in Figure 1.
The wire layout shown in Figure 2 could be modified to compensate for potential cold spots and ensure heating is evenly distributed. The thermal analysis is also useful to correlate the temperature at the sensors to the tray top. Currently, we are using a linear fit, but more testing is needed to find the spatial relationship of temperature.
The heating element shown in Figure 2 has a wire surrounded by insulative silicone and has additional solid insulation below it. Currently the extra insulation is used more for structural padding then actually insulating the electronics. This extra insulation likely can be removed after a redesign of the tray body.
Special thanks to Michael Bingham and the entire Jump the Moon foundation for all their help on this project!