Sarthak's Reflection

ME250 was one of my most challenging and time-consuming classes this semester even though I had three other 300+ level courses. It required a lot of time and dedication towards the project, especially near completion and the competition. I was pretty new to the in-depth design process that Professor Hart presented to us, and it was definitely an eye-opener and will really be helpful in the future. There are a lot of things I learned in ME250 such as efficient design and manufacturing as well as working as a team. I learned that we needed to start off creative with our designs and funnel down our ideas in the order of strategies, concepts, modules, and components.

Prior to my experience in ME250, I had very limited background with basic manufacturing processes. I feel I learned quite a bit about the design and manufacturing process during this class. One thing that I found challenging was trying to initially design our machine in CAD. Using SolidWorks and building our project step by step showed me how important it is to have a strong computer model in order to reference and be able to visualize the final product and make crucial changes. I learned how helpful CAD can be in a design aspect but also in a manufacturing sense because it makes creating part drawings so simple and efficient. In manufacturing the individual pieces that made up our final machine, I learned a great amount about the precision that needs to go into such processes. I also gained a good understanding of how to perform processes like milling, drilling etc.. I feel that in learning how to do all of these things in this class, I will be much better prepared for challenges I will face in ME350 and ME450.In lecture I learned more about the theory and mechanisms behind screws, bearings, and springs, among many other .The lectures and assignments helped to guide us through the whole process while teaching us various manufacturing skills. All of the lectures on ways of gaining mechanical advantage were very helpful overall knowledge and proved to be very useful while manufacturing parts as well as analyzing our design.

Working in teams was not something I hadn’t dealt with before. Even though by the end of November we had been trimmed down to just a team of three, with one person dropping out, I can say I learnt a lot about teamwork and channelizing our collective efforts towards achieving our goal (i.e. completing our machine). Utilizing everyone’s individual talents was good because we could all learn from each other and gain personal skills from working together. Time management was another big issue for me because no matter how much we planned ahead we always felt like there was not enough time to finish.

I felt the course could be improved by making the earlier part of the course have more assignments on what you actually want to build instead of making up random strategies. I also felt the course was a little disjointed from time to time with the assignments. The length of certain homework’s in the beginning should have also been scaled in accordance with the grade. I also felt that the exam was too long to complete in the given time and doing well became an issue of who could write faster and not who had mastered the material.

ME250 really built my engineering skills in general. I think that there is a certain mindset that an engineer needs to develop, and I feel ME250 really forced me to develop that necessary mindset. Although I still feel I could have put a bit more time into refining our final machine, the sight of seeing our machine performing in the expo was a gratifying sight. I am also extremely grateful for the effort that all the GSI’s and Professor Hart put forth to produce a more effective introductory design program. I think a new standard was set for ME250. I more over feel that all the things II have learnt have left me in good stead for the future.

Final Reflection

During this semester, I learnt about the safety standards that we are expected to meet in manufacturing labs in general. In terms of design, I grew familiar with the CAD-program Solid-Works and its different features which proved essential in the manufacturing stages. It was very useful in terms of also demonstrating the scale of each part relative to other components of system (i.e. assembly). Solid-Works proved to be useful when using the water-jet and the laser-cutter as we simply converted the files into a drawing and saved it as a different extension. I also learnt the standards required for engineering drawings. In terms of manufacturing, I learnt about basic manufacturing techniques like milling, lathe, waterjets, laser-cutter, drilling, bending, press-fitting and others. I learnt about the functions of basic components like bearings, shafts, gears, fasteners and pulley systems.

Team-work was the key to making the design/manufacturing work. The project was designed such that even if a single person had all the know-how regarding the project he simply would not have had the time or the success or a team that employed the work of three people. It was essential that we bounced ideas off each other and improved on them given the time-constraint. Eventually, the final idea would a combination of three different initial designs but with none of the flaws. Given the scale and time-constraints of the class it was vital that the work was evenly distributed in order for progress to be made. It was important to realize that everyone had different strengths for example someone was better at drilling than the next person so he should look-after the drilling procedures however this is not implying that the others should depend upon him solely. It was important to make sure that the team stayed positive and that it did not fall out which taught me how to introduce or decline ideas with subtlety and have more patience whilst explaining them.

Time-management alongside team-work was pivotal. It was essential that deadlines were met and that we had a schedule that showed us our milestones for each week or day depending on the intricacy required by the component or module. Furthermore, time-constraints were placed on when the laboratory was open and when certain types of machinery were made available to us. All these factors had to be considered in order for the design of a successful project.

The course was enjoyable but straining at the same time. I picked up so many little things alongside the major manufacturing tricks from this class especially since it was an open-ended design project. The class was planned out carefully so that everything we needed to design/manufacture was covered in lecture. It would however be more beneficial if assignments were returned on time and so that we could see what the question was really looking for. It would also be convenient if there was a core-location that showed where due-dates were shown rather than scattering them across Ctools or Google spreadsheets. The GSIs were great and were always available to answer questions and help out. Overall, though this may have been a tougher than usual ME250 class but I would definitely prefer this one as it would be more beneficial in the long-run.

There were a few ways in which I could have improved my performance in this course. I could have dedicated more time had it not been for the other courses. The design of the project worked but since we did not focus on the small details due to other limitations, it was slightly flawed. For example, we did not analyze the springs we were provided with sooner. We could have used a lighter material for building the arm like the acrylic which would have spun faster and would reduce the torque input from the motor. We needed a better method of fastening the wheels to the motor so the cart would function more smoothly. Also, we could have added more motors to the cart so that it would generate more torque so it could meet its functional requirement of being obstruction to the opponent’s vehicle.

Shikhar Mohan

Final Reflection by Kevin Leach

Final Reflection
by Kevin Leach


In ME250 I learned a lot about some of the most important parts of the design process including teamwork, design and manufacturing, time management, and the most common components used in a manufacturing based environment. Throughout the semester it was very evident how important teamwork was. What I realized was that teamwork can be far more successful than individualized work when done properly. By collaborating ideas and using each person’s strengths to execute them in an efficient manner what can be accomplished by a group can only be constrained by deadlines or cost, not by lack of knowledge. Design and manufacturing was definitely the most crucial part of the design process. What I learned was that the more detailed your final design was after deciding on general strategies and concepts, the easier it made the manufacturing. I also learned that you should complete all design for a module and if possible test it using 3D modeling on a computer to make sure everything fits together properly before manufacturing of the individual pieces because if a part is made to the wrong size, that material is often unusable. This can become costly if parts are had to be repeatedly remade. Tied into teamwork, design and manufacturing is time management. Time management is crucial to each of these components of the design process. In the business world, as in this class, deadlines are set based off of costs and expected income. If these deadlines are to be met decisions must be made in the design of a product based off of its functional requirements so that it can be manufactured with enough time for testing. If we don’t set deadlines than we may just keep redesigning with the desire to make something perfect instead of viable and then nothing essentially gets finished or it takes so long to complete that it becomes too costly. So, regarding time management I’ve learned to set your own deadlines for completion ahead of schedule to allow an ample amount of testing time so that overlooked flaws can be fixed. I was also glad to learn in more detail about the basic individual components used in design like gears, bearings, fasteners, etc. In learning about the specs of these components, how they work, and what they are most commonly used for it helped me better visualized them working together.

In thinking about how the course can improve, I can honestly say that it was very easy to tell that this was the first semester after the class had been restructured. Information that would help the students was often given to us at inopportune often later than needed times. This like detailed grading rubrics for assignments, tips on manufacturing or putting stuff together, what’s in the kit, what the final arena would look like, etc. There was just a lot of little changes that were made throughout the semester that it would have been helpful if we knew them sooner. A lot of this probably won’t be an issue in the future if the class remains the same but how everything is going to be just needs to be finalized at the beginning of the semester. I also especially would have liked to know what’s in the kit at the beginning of the term, this would have helped a lot with the early individual strategy and concept assignments. I also think that the arena could be improved so that there are most possibilities of scoring and moving around. As we saw, everyone had some type of arm because the slot was so tight fitting around the balls that that’s the only way you could get to them and thus the rest of the arena wasn’t even used by any team (like the holes and bins). Lastly, regarding the exam, I agreed with reducing the percentage of what it was worth for our grade but I think in making the test longer than one could possibly finish in the allotted time was not beneficial at all for us students. With the shear length of the test one was simply rushing through it the hole time scrambling to get as many points as they could instead of showing what they really know and can produce. If the test was shorter and one could focus more on the problems they could perform better and learn more from the experience, you don’t learn anything scrambling for points because of lack of time.

I think I could have improved our performance in the course by being more detailed in our design before we started manufacturing. This would have made our arm especially run more smoothly than what it did. I think that we could have made some better choices in the materials we used with what we were given. We probably should have made our arm out of wood so that it was lighter and thus wouldn’t have taken as much torque to rotate it especially since our shaft was small. I also think we should have made our defense cart bigger and heavier and chosen a different way of coupling the rear wheels to the double gear box. The functional requirement of the cart was to get in the way and stop any forward movement of the opposite team’s cart and with these changes we would have better met this requirement.

Final machine

Our strategy was to use rotating arm attached to a motor which is positioned in the center of the slot. It scoops up ping-pong balls and launches them onto the opponents side.The arm is operated using the fixed axis motor, with power being transferred to the arm using a shaft-key setup.The key has teeth so that it can mesh with the arm.The shaft on one side has a pulley attached so that a belt can be used to transfer power from the motor. The shaft has been milled(roughly a semicircle) out on one side so that it can facilitate the key, so as to not let the key slip. A 90 degree torsion spring has been incorporated into the design so that the bucket can move inside the groves in the main arm body as well as stay stiff.
Our defensive strategy was basically to impede the opponents from scoring. The cart will serve as an obstruction to the opponent preventing them from launching there mechanism i.e. we will use our cart to ram and block the opponent.

Here's our competition preview video. Unfortunately the file was to large for it to be played on the actual competition date, so here it is now!

Drawings for the ARM MODULE

Finished Cart

Final Bill of Materials

http://spreadsheets.google.com/ccc?key=t2N_AC04M4qGnntAnpmRl5w

Design-Expo

Competition Day:
The potentiometer for the fixed-axis motor has been fixed now allowing us to change directions at will as opposed to when it only allowed us to rotate in one direction and if the direction was changed the motor would draw large amounts of current more than the motor could handle and would subsequently short.

The results were dramatic. Our arm was moving faster and was more responsive. It scooped the balls out with relative ease and tossed them into the opponents tank. We were seeded 26th but managed to upset the 7th seed thanks largely to our defensive cart that obstructed the movement of their cart. In the second round, we again performed well but were unlucky as we knocked ping pong balls out of the arena which counted against us in the tie-breaker.

Overall, we were satisfied with the performance of our machine. Improvements we should have made had time been more forgiving:
a) a lighter material for our rotating arm
b) a more suitable way of attaching the spring to our collapsible arm. this would have allowed us to scoop the balls further away.
c) one of the wheels came undone on our defensive cart and hence started to slip even before the competition started which obviously went against us.

Final

The project has finally been assembled. The key shaft was redesigned and now is epoxy-free! We altered the shape of the shaft hole by making it roughly semi-circular and milling the corresponding portion of the shafts.

Defensive Cart: Success

The defensive cart worked like a charm. We set the gear-ratio to the maximum possible on the double-gearbox 344:1. We figured that more torque would be better than frequency as we simply intend to disrupt others and in order to that we need more grip, more torque!