Week 4 was a big week for my team. We selected our final solution, presented our work in a mid-summer presentation, and began planning how we will implement our design.

In my last post, we had narrowed our options to two solutions. These two solutions were very similar to one another: they both used a roller-coating method and a syringe pump. The main difference, however, was the overall structure of the machine. We were debating whether to choose the loop method, where the film was moving in a belt underneath the roller, or the track method, where the roller moved along the stationary film. In the end, we decided that the loop method was a better solution because a) the overall design was more compact and did not exceed our size criteria b) it would be much easier to implement because fewer complex components would have to move.

After we had really talked through our idea and what it would look like, we began making low-fidelity prototypes of our vision. Each team member made a prototype to ensure that we would each have an equal opportunity to communicate our interpretation of the design. It really helped us communicate our complex 3D ideas because we could see a representation of what our final product will look like.

In this solution (shown to the right, apologies for the poor quality), the syringe would contain approximately 8 mL of the heated photographic emulsion. Then, the user would begin turning the hand crank. This crank is the driving force of the entire machine. It will move the film belt loop along underneath the roller. At the same time through a series of gears, belts, and pulleys, the hand crank will also push the syringe to drop the emulsion onto the roller via a rack-and-pinion mechanism. By having everything connected to the hand crank, we can control how fast the film moves relative to how fast the emulsion is dispersed from the syringe. The roller itself is actually free-rolling, meaning it will roll on its own as the film moves underneath it. After the emulsion has been applied, the fan cools the emulsion down to solidify it.

One drawback of this design is that we will need to wait a few minutes to apply the emulsion to the entire six feet of the film due to the belt loop structure. We need to make sure that the gelatin is solid before we turn it upside down to coat the other half. Even though there may be some waiting, we believe the convenience of the hand crank and the compactness of the design will make up for this fact. We presented all of these decisions and goals in a 15-minute technical presentation.

After the presentation, it was time to start thinking about implementation, but how would we do it? We were especially concerned about synchronizing the syringe pump and the belt loop. None of us have any technical expertise in mechanical machines, so we had done lots of research into belts, gears, and pulleys. We then began sketching various ways to arrange these mechanical parts to achieve our goal.

Once we came to a consensus, we were ready to begin gathering our parts. Unfortunately, there was another obstacle we needed to hurdle, knowing the exact specifications of each part. For example, we knew we would need several gears, but how big did they need to be? What pitch should they have? To answer these questions, we needed the most basic form of engineering, math. I won’t bore you with the details, but we essentially needed to find the relationship between how fast the film was moving in relation to how much liquid was pumped by the syringe. If we quantified this relationship, we could determine the right gears and pulleys to use to achieve this relationship.

In the middle of these milestones, we celebrated the 4th of July! The internship gathered together, cooked burgers and hotdogs, and enjoyed the fireworks from our own private view on top of the Martel sundeck. It added to the enjoyment of an exciting week. Moving into next week, we know what we need to do, how to do it, and the means of doing it. All we need to do now is actually start building! We are really looking forward to how our plan will develop and become a functioning product.