Part 3, Beam Project: Construction of 3D Mockup from Foamcore & Materials

Final Project, Part 3

While we were finalizing our materials and waiting for them to arrive, we built a foamcore model, as shown below. It is a simple design of what we imagined our beam to look like. Looking at it from the lenses of after the final project and even at the moment that we built this, we knew that this was simplifying the realities of building our balance beam. For instance, as the paper shapes show us below, sticking LEDs to wood would not be as sticking paper to Styrofoam.  What this model did help us with though, was that it raised questions about the placement of components, allowing us to hash out a few more details to the process of building the prototype. The foamcore model below has dimensions of: 2 feet long by 3 inches wide by 6 inches tall. At this point, we didn't realize we were limited to the Arduino's limit of how many sensors could fit. We made this beam 2 feet long because we only needed a portion of the beam to show how the shapes would fit in.

Lessons from the Foamcore Model
Occupying Space (spacing further improved after prototype)
How much space should each shape take up? What shapes should they be? After talking with the director, we knew that wanted simple shapes, but what shapes could be possible given the LEDs we have? To be simple, as shown in the foamcore, we initially had a heart, square, rectangle, and triangle. For spacing, we decided that allowing each shape to occupy 6 inches (length) by 3 inches (width) of space, which was a reasonable foot size for 3 - 5 year old children. It would be okay if the foot was smaller/larger than the shape. If smaller, the child would see the more of the light underneath her light, and if larger, the child would be able to cover the entirety of the photocell, ensuring she would see the next shape blink.

Hollow? Solid? 
Before we could buy wood, we needed to be clear about whether the beam would be hollow or solid inside. If hollow, we would need planks, and if solid, it would be a block of wood. We went with hollow (so, wooden planks), because we needed space to store the wires, Arduino, and breadboard(s).

LEDs/Sensor...Where Would They Go? 
It took us a while to figure out how to place our LEDs without distracting the children walking on top, but we eventually agreed to chisel grooves into our wood. This would allow the LEDs to sink in and we could drill holes at the edges of the grooves for the wires to go beneath. This method would work for the placement of our sensor too, where we could be chiseling a deep groove so that children won't be bothered by the bumps of the materials on top as they walk on the across the balance beam.

Base Support 
We needed to support the base of our beam so that it doesn't wobble as children walk across. In order to incorporate a mechanism (a requirement that we thought we still had to meet), we thought we could make our support base out of Delrin. (This, of course, was later shot down by Amy...the base would be extremely unstable with method we thought of.)

LEDs, What Should They Be? 
Strips, or individual LEDs? We went back and forth between strips and single LEDs. With strips, there wouldn't be as much wiring (there was still a lot in the end...)

If we had single LEDs though, making shapes like hearts or ovals would be easier, since we would only need to follow an outline to create the shapes. We had no strips to test with, and as we finalized our materials at the end, we decided to work with strips. There were not enough pins to utilize all of these single LEDs, and the wiring process would be a nightmare.

As we thought more about the dimensions of how long the beam should be later on, we included the Arduino's capacity into the equation. Since there were only 6 slots (A0, A1, A2, A3, A4, and A5) available for us to use a sensor, we decided on a final beam that would be 4 feet long and use 6 shapes (a sensor is needed for every shape). For the prototype, we would only need half of the length of the final beam (so, 2 feet) to show how the whole beam would work.

Materials?
It took us a week to settle and finalize the materials we would need to build our beam.We were researching which sensors we could use that would still be within our budget ($100), and although we came up with quite a few options ($5 load sensors, touch sensors, etc), we eventually went with:

• photocells (6, one per shape, already have)
• LED strips (a few meters, two different types of strips, different colors)
• 4x4 wood (2)
• planks (3 inches wide by 6 feet long) 
• 9v battery pack with cap
• breadboards (2, medium)

From left to right: Photocell, RGB LED Weatherproof flexi-strip 60 LED/m,  Wire Light LED Strand, 12 Warm White & Blue LEDs + Coin Cell Holder (2), 4x4 Wood

I hope you won't have trouble imagining the images of planks, battery packs, and breadboards...both varieties of LED strips were purchased at Adafruit

Eventually, we also had to add transistors to our list of materials in order to wire one type of the LED strips to our breadboard/Arduino. 

Small Reflection (After Completion of Final Project): If I could redo ordering materials again, I wish we could have only ordered the 2nd variety of LED strips. The first (RGB LED Weatherproof flexi-strip) eventually became a soldering and wiring nightmare...