And the winner is...

Not us.

But that doesn't mean that the semester was all for nothing.

Coming into ME250, I was excited to take my first true college level mechanical engineering course. Prior to the start of the semester, I ran across the Slotbots video from last year, giving me a general idea of what to expect in the class. Having completed four years of mechanical design in high school, I came in comfortable with the ideas of computer design, dimensioning, threads and fasteners, and had experience using many of the machines. After spending my senior year building an electric vehicle, I was looking forward to get back into designing and building.

Having focused on learning AutoCAD and Inventor in high school, trying to switch to SolidWorks initially seemed like a difficult, and possibly unnecessary task. However, with the labs and investing time outside of class, I quickly saw the similarities between the programs, and am now equally as efficient with them all. In fact, Solidworks has many analysis options that I wasn't aware of when using the Autodesk programs. I am sure having knowledge of additional software will be useful when entering industry.

The lectures were my first real opportunity to learn about mechanical components in detail. Information about parts such as gears, motors, bushings, bearings, and couplings is knowledge that every engineer needs to have to be successful. The lecturers did a good job of explaining the intended uses of each component. However, implementing and combining them into a functional design had a large learning curve, which probably could have been better assisted in class. More practical, hands on examples of how the components are chosen, assembled, and operate may have been more beneficial than slides of very specific equations that only relate to specific situations, and didn't affect our project. Similarly, while material processes were interesting to learn about, without an in-depth explanation to how they work, and with no need to utilize them for the project, the time may have been better filled with other information. Overall though, the lectures served their purpose and delivered a lot of new information, and the slides will serve as useful reference material in the future.

The assignments were well-intentioned, and helped teach the design process, but often were not able to be integrated with the project as planned. The initial assignments asking for strategies, concepts, and modules were drawn out over too many weeks, cutting into potential shop time that was desperately needed. Since nearly everything had to be repeated collectively once groups were formed, it would have been better to make at least the final stage a group assignment. This would have given the teams more time to get acclimated and come up with a final approach.

One thing I quickly got a feel for was tolerances. We discussed the idea in high school, but never took it into the manufacturing phase. After getting points docked for tight tolerances on one of the early milestones, I saw the benefits of accurately determining how much room for error there is on a given part.

In regards to teamwork, the majority of us were able to work together and had a common goal in mind. Though we all came into the group with our own ideas for the design, we were able to collectively choose a strategy and work towards carrying it out. However, some avoidable tension caused the team to divide and each focus on a module. During the process and in hindsight, it would have been much better for the problem to be settled at the beginning. Instead, I attempted to act as the connection between the two sub-groups, but often found myself unfamiliar with a new direction that the cart had taken.

Both modules underwent numerous design changes throughout the semester. Reasons for these changes included better ideas, manufacturability problems, performance issues, and time constraints. This involved making numerous CAD drawings, testing our ideas in SolidWorks, and creating manufacturing plans. Between these revisions, time was spent determining how to allocate the materials provided, what we needed to purchase, and what tools to use to make each part.

Time spent in the shop included both high and low points. Bob and John were always willing to help, and there immense knowledge of machine processes was priceless. I had never seen a waterjet or laser cutter before, and using both machines in our manufacturing process was a new experience. I was impressed with how quickly intricate parts could be cut straight from the CAD drawings. However, not everything came so easily. It is no secret that the shop was often packed, and with only a few mills and lathes, the supply of machines fell far short of the demand. Time spent waiting for the machines to become available often exceeded the time spent on them. Though a solution isn't easy, more shop time and more machines are definitely needed. I feel that the timeline should have varied more from last year's competition to account for the fact that multiple modules had to be created to compete this year. Throughout the semester and down to the wire, shop time was at a premium, and influenced our final product. However, considering the time given, I believe we were able to produce two functional modules that gave us a shot in Slotbots II.

A couple of our designed parts for the chute proved to be difficult to produce. We first attempted to build the two rails out of aluminum stock. A couple hours into the machining process, it became clear that the methods necessary to do it right were not available to us, and that we were unable to build them to the tolerances needed to ensure the sliders did their job. After much frustration, we finally decided that purchasing rails and sliders from McMaster would be the best option. This experience showed me the importance of making sure the parts you design are able to be made with the available machines.

Secondly, both the vertical and horizontal chutes we designed were made by bending thin sheet metal. Though the bends looked simple enough on the SolidWorks model, it became a whole different story when we attempted to use the metal bender. It took hours testing different techniques using a combination of the bender and a rubber mallet to get our desired results.

The imposed limited outside budget of $100 added another learning experience to the course. It is amazing how fast the cost of small components can add up, and how expensive some can be. In fact, we ended up using nearly every penny available to complete the project. with the rails consuming a majority of the budget.

The competition, ultimately, turned out to be somewhat of a disappointment. Watching team after team fail to score was not what I expected at the start. After seeing many of the modules teams had built function as planned during individual testing periods, including ours, performance seemed to decrease leading up to and during the final event. For example, our video shows our cart cruising across the table and depositing balls in the hole in only a few seconds. However, during the seeding round, and even worse during the competition, the power supplies seemed unable to provide the juice needed to run the machines as intended. It is disappointing that after months of work, the results could have been affected by inadequate battery packs. Having seen our cart operate much better than it did during the Design Expo, it is easy to believe that the results could have been different. Many other groups felt the same way, and more emphasis needs to be placed on ensuring that all power supplies are fully functional each and every time. Larger motors would have been beneficial as well. The competition would have been much more interesting and had better results if focus was put on these two things.

My performance in the course could have been improved by finalizing a design at the beginning and working out all possible problems, instead of having to go back and change ideas midway through. Finishing the modules earlier would have given us more testing time and allowed us to make a couple additional changes, as well as determine the optimal starting positions for the modules and plan of attack during the competition. With every group finishing nearly at the deadline, controllers were scarce and time was even scarcer.

Overall, I enjoyed ME250, and will use the knowledge I gained as I move forward through the rest of the mechanical engineering curriculum. The class was well run, and every professor and GSI involved worked to share what they know with us. A special thanks to Professor Hart, Mike Umbriac, Mark, and Bob and John for a successful semester!