The week 8 prototype

At the end of last week, my goal was to finally put together the electronics and come up with an exhibit that could be tested on the floor. While the main goal of this consisted of adding the electronic components, there were several piece of the exhibit I wanted to refine.

The Week 7 Prototype

By the end of Week 7 I had a prototype that was pretty exciting.  I just couldn't get it to work on its own yet.  I had changed the exhibit around so that the wax flowed over the sides of three layers of terraces.  While I had tried using mirrors and other methods to make the wax more viewable to the user, this method seemed best.

Prototypes working toward the week 7 model

While this worked, I wanted to play with the shape of the terraces and angle at which they were slanted. After looking at a wide variety of shapes and testing them out of paper, I decided on an organic shape that reminded me waterfalls that I've seen.  I also spent time texting which angle would be best for the wax.  I then used the power nibbler to cut out the terraces, which needed to be metal so that at the end of the day they could be heated to melt the remaining wax.

After building and attaching the terraces to a stand, my next challenge was preparing the circuit and making the pieces that would melt the wax.  Testing out several prototypes in plastic and wax, I settled on a design made out of sheet metal that I felt would best melt wax and allow it to flow out onto the terraces. While making wax melters that were functional was important, these pieces of metal that would rise to very high temperatures also needed to be safe, so I attached wooden tops to each such that they would prevent direct contact with the metal through a wooden barrier.

Sketches of possible designs

A plastic prototype 

The final wax melters 

The last piece was to create an electronic circuit using resistive wiring that would heat the metal.  While I initially had no idea how to approach this, one of the TAs showed me that the pink foam cutter in Room 36 operated using nichrome wiring and had a homemade circuit that I could copy, which was my goal.  Once I had all the parts in hand, I tested out the circuit with the wiring which was largely successful as it generated enough heat to start melting the plastic on the alligator clips I was using.  

While the circuit worked well on its own, there were several instances I hadn't accounted for.  First of all, I realized that connected the wiring to the melters was more difficult that I initially thought, a mistake that I will fix in my next phase of prototyping.  On the other hand, I failed to account for the load in the nichrome wiring.  While I had copied the circuit almost exactly from the pink foam cutter, I never measured the resistance across the wire, so when I ran the current across the circuit I built, within a few minutes the transformer heated up and was blown out.  Moving forward, I plan to troubleshoot further and make certain that the heating element has an appropriate resistance such that I do not blow another transformer.  I hope to fix both this and the melter by the coming Friday.

As a result, my piece was unable to be put on the floor for user testing.  Nonetheless, I had the chance to look at my classmates exhibits and how the visitors interacted with them.  Dan's electric radio was by far the closest to mine and gave plenty of insight.  With such a dangerous phenomenon, he placed a plastic case around the electric charge, something I plan to do with my exhibit.  While this did put a wall between the visitor and the phenomenon, he put the exhibit at the edge of the table so visitors could get as close as possible, which they did with eagerness, something else I plan to take into account for my final prototype.

Something else among the many other things that I noticed during my time at watching visitors play with others' exhibits was the importance of draw and placement in the museum.  For example, the darker parts of the room were much less often frequented than the lighter parts.  Even with Clementine's exhibit which displayed a bright and fun mirror box, visitors were much more likely to play with the exhibits in the lighter parts of the room and that were closer to the entrance such as Winnie's, Emily's, Dan's, and others.  For me, this underscores how important having a light setup is to my final piece.  However, for next Friday my goal is functionality.