Element E

Application of STEM Principles and Practices

Element E

Element E analyzes the STEM Principles that are applicable to our solution. This is the research done to solve certain issues or make design decisions pertaining to our design requirements.

Material

Given that our solution will be 3D printed, we looked into two of the top 3D printing materials: PLA and PETG. After research, we found that each of the materials had its strengths, along with weaknesses. We found a very informative and credible source by CNC Kitchen that had performed many tests and provided valuable results:

Based on the results, and the information in the research, while every spool of PLA and PETG will not be the same and have the same amount of strengths, based on our needs, we will be moving forward with a PLA filament. PLA has a greater maximum force load in both the XY and Z directions, along with a better-bending modulus. On the other hand, it has a smaller impact strength and heat resistance, which is not as big of an issue as our product will not produce too much heat, nor have any compressive forces acting on it for long periods of time.

Adhesion

Due to light switch plates commonly being made of plastic, we decided on a sticky adhesion over a magnetic one. The sticky method would help our device be more universal and decrease installation time.
“The most common plate material is plastic (also called polycarbonate), a sturdy and inexpensive nylon that can withstand years of use without cracking.”
Standard switch wall plate

Circuit

Our circuit contains:
- - PIR sensor
  - 9V battery
  - Arduino nano
  - Servo motor
  - Push button
  - Breadboard
  - Wires

Battery Life

Due to our calculations, the prototype would only last about 15.1 hours while consistently ran. Hypothectically, we would create a custom PCB and have a better battery to improve run life in the future.

Force

How much force does it take to flip a light switch?
We tested to see if the servo was capable of enough force to flip the light switch
1N is the required force to flip a light switch.
Based on our own testing, along with the research linked above, depending on the light switch, it will take anywhere from 1 to 5 Newtons of force to flip a light switch.

IMG_9963.MOV

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