Sunday, December 13, 2009

Nathan Thome's reflection

ME250 was my first opportunity to design and build a complex machine. 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 without being able to handle the parts or touch the arena. All of the design and build work that I have done before allowed me to be hands on with whatever I needed to build and where it would operate right away. The fact that I couldn’t get in the arena with some materials right away made me have to do a lot of research that I wasn’t used to. Going over the materials list and looking up arena dimensions in CAD made me have to visualize what our product needed to be like without actually being able to see anything in front of me. This was frustrating, but I realized that engineers go through that process all of the time. This class really built my skills for predicting outcomes and foreseeing problems and constraints when given simple information. I feel this class really prepared me for future problem solving.
I’ve done a lot of team projects in my past, but of course, ME250 gave me new experiences. I think the fact that this project lasted an entire semester really challenged my team and resulted in everyone having to step up their skills. I noticed right away that each of my teammates and I had our strengths and weaknesses. While some of us took over CAD drawings, others created PowerPoint presentations and blog posts. Eventually though, all of us participated in every activity. My CAD skills grew because I had teammates that were really good at it and who helped me along. At first I was timid with my ideas because I had very little experiences building complicated projects and my shop skills were not very good. This lead to me taking a bit of a back seat when initial ideas were discussed. However, as time went by, I grew more comfortable making decisions and I feel in the end I offered an equal amount of production as my teammates did. My teammates and I disagreed a lot during this project, so my people skills grew substantially. I had to watch my temper and be polite with my opinions. My skills as a team member grew a lot during the construction of our machine.
As far as time management goes, I learned how to shove a lot of work into a specific amount of time. I really had to plan out my week ahead of time and see when I could get to the shop. Due to shop operation times, I really had to consider how to handle my ME250 work along with other schoolwork. In the end, I learned how to prioritize and schedule work well in advance.
Apart from all of the material that was planned for me to learn, 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. It’s hard to explain, but I think it really comes down to analyzing situations. In the beginning of the project, my teammates and I would come up with an idea and just assume that we would get it to work without any problems. Several problems later, I learned how to question myself right away when I came up with a new idea. It went from saying, “Here’s an idea. Okay then.” To, “Here’s an idea. What can go wrong? Will this work as planned? What if this scenario comes up? What if that scenario comes up? What could be the maximum force on this and where would it come from? What’s the maximum force this object can withstand? Is there a way to alter this to make it better? Do we have all of the necessary materials? Can we manufacture this? Can we manufacture this in time? Is this actually possible given all of the constraints?” By the end of the competition I was almost constantly asking my teammates questions to make sure our machine would work the way we wanted it to. ME250 taught me to mentally test what I was building before I event started designing it on paper. I feel this class developed my engineering skills more than most that I have taken because my options were so open.
When I compare what I did in ME250 this semester to what previous students have done I’m blown away. My social life and sleep schedule may have suffered, but I’m really glad to have been able to participate in the redesigned course. After seeing our exhibit at the design expo I really had to appreciate the fact that U of M put forth extra funding for this class and that Professor Hart put forth so much effort to produce a more effective introductory design program. I think a new standard was set for ME250. This semester’s class was a great starting point, and I personally have a few ideas that could improve the program even more. Lectures were tough. It’s understandable to have trouble with the loads of information that we received. One thing I thought worked really well was when Professor Hart sometimes broke up the lecture into segments by using videos and hands-on activities. I think the lecture series could improve by involving more hands-on experience for students. If Professor Hart introduced more frequent activities or even group discussions in lecture I think the turnout would have been a lot higher. I also felt that the homework sometimes didn’t correlate with what we were learning. We had to solve certain physics problems (a kinematics problem comes to mind) that just seemed completely separate from what the class was actually about. I think if the homework involved more things correlating to lectures such as problems where we would find gear pitches, choose between bearings for components, determining torques, and brainstorm ideas for situations (much like the first exam question), students would have been less frustrated with the work load. I also think there could have been a bit more incentive for competition. Our machine was built to compete. It wasn’t the prettiest and it wasn’t the strongest, but we knew we had to move ping-pong balls, not bowling balls. I’m sure we were graded down on certain things that didn’t affect us in competition and I think bonus points could have been awarded for placing well (or being the only team to move a squash ball) to balance out any manufacturing issues the staff had. I also think the final examination of our machine would have worked better if we had a chance to review what was wrong with it before the actual grade was written down. I think certain manufacturing choices on our machine needed to be explained. For instance one part of our machine was only riveted on one side instead of both, but if we riveted both sides we ran the risk of increased friction on certain moving parts. Although the manufacturing wasn’t the best, it was necessary given the creative choices of our machine. I also think it would have benefited the staff for grading machines if we had to submit a write up about why we made certain choices along with our machine for the final inspection. For instance, my team initially wanted to use a lead screw system to move our machine. That was before carpet was added to the arena. Once we noticed there was carpet, we came up with the idea of using Velcro on wheels. This made manufacturing our machine easier. I think it should have been noted somewhere that our team effectively adapted to changes in the arena which ultimately affected the positives and negatives of our machine design. If my teammates and I planned on using Velcro wheels from the beginning our arm would have been designed much differently. I also think creativity should have been a factor in grading. Two teams came up with ideas that were completely out of the box and very different from other teams. Even though those teams did not seed well, I thought they should have been rewarded for being as creative as they were. I also don’t think grading should have been placed on seeding opposed to grading based on competition. I think it should have been a combination of both. My team was seeded considerably lower than the first seed, but our machine operated much better in the actual competition.
As far as my performance goes, I wish I had learned how to use the mill, lathe, and laser cutter more. I was very new to using power tools and machine equipment and often relied on assistance from my group members to operate them. I regret not building my shop skills more. I also think that I was too timid with my opinions in the beginning. My lack of design experience made me shy about my creative ideas. Near the end of the manufacturing process I mentioned a few ideas to a teammate and he asked me why we didn’t do that to begin with. Although I think the entire group dynamic had a lot to do with our decisions, I regret not speaking up right away and being more involved with decision making in the beginning.
Overall I really enjoyed the redesigned ME250 class. I learned a lot and had some fun along the way.

The Semester in Review - Michael Czarnecki

This semester turned out to be a pretty good time in ME-250. Although the class was extremely challenging at times, I was able to learn a lot about the manufacturing process and the importance of time management. I will say that I was very fortunate to be on a team where all the members equally contributed and we were all committed to a single goal: doing well in the slot-bots competition. I was very pleased with our third place finish and have come to see that all the hours I put into this project were really worth it. I, and I think all my teammates, had a really good time this semester.
Before this semester, I considered myself a pretty hands-on kid; I have grown up using tools my whole life. However, I learned more this semester about machining then I ever thought possible in such a short time. I think that this is due to the sink or swim aspect of this class. We received some basic training and Bob, Marv, and the whole ME-250 staff were always very helpful, but in the end we really had to figure it out by ourselves. I am glad that I got the opportunity to work on heavy-duty machines like the mill and the lathe. These machines are essential in the manufacturing process, and I feel as if I have received some experience using them that will give me a great advantage in the future. The same goes for the design process. We were stressed with the importance of critiquing designs and weighing them compared to other options. In my opinion this was one of the most important parts of the semester because when push came to shove if your design wasn’t good enough, then you didn’t have a chance of winning the competition.
The team aspect of this project was vital. Within my team, we needed each other’s advice and feedback when designing and building our machine. It was truly a collaboration of all four member’s creativity and skill. We really learned a lot about the importance of time management. When we began machining, we would often all worked on a single part. This often led to one or two people working and the rest of our team just watching. We quickly learned that to get this project done we had to split up. Saying this, it also became more important that we stayed in touch giving others updates of our progress. This was especially important when we would slightly modify a part. We had to make sure all the teammates knew if something was changing and what the impact of those changes would be on other components of our design. We also learned the importance of doing it right the first time. Too many times we would have a part half made then slightly mess it up; this was a huge waist of our time. I think I learned how critical it is to measure twice just to confirm you were doing it right. The team aspect also brought forth a couple of instances of working with someone I didn’t always agree with. I learned that there was no time for drama this semester. We openly debate subjects instead of arguing allowing the team to continue working in a positive manner.
I think this course was well constructed in the sense of going through the design process then allowing us manufacturing time to concentrate on our machines. At times, especially early in the semester when the FRDPARC tables and CAD assignments were overlapping each other, things got a little hectic. I think, if anything, this course might need to ease up on the density of work. Saying this, I look back and see every part of the design process as a critical component to my knowledge and see little you can cut from this class. One suggestion would be to ease up on the Homework sets we had. I found that often these had the least relation to the final project and sometimes were unnecessarily difficult.
Students were required to perform at his or her best all semester. I think that a key component to giving it your all was staying focused and hopeful. Sometimes, I saw students get defeated by the workload, but you just had to accept it and work through it. I think that I truly dedicated myself to this project; however, that I could have improved my performance by not being lazy in the design process. At times, my teammates and I just thought that some things were just too hard to do and that we could make due by doing it “unprofessionally”. This really comes to mind when we were mounting the gears to shafts. We originally used epoxy to secure them, but as we began to test our machine the bonds would break. We had to keyhole the gears and shafts in the last week of the course, which ended up being rather stressful and time pressing. Also, I think that I had to take the analysis more seriously. I mean we made good analysis for certain components of our machine, but not all of them. This was clear when the gearbox of the double gearbox broke during the competition due to over loading it. I think that the whole class needed to do this seeing that three of the final four teams in the competition had broken machines.

Jeff Plott's Individual Reflection

I learned and improved many skills involved in both design and manufacturing.
One important thing I learned is how to find out the properties of different materials and what each property means in terms of how it can be implemented in a design.

Another thing I learned is the different types of fits that can be used in a design such as a clearance fit, transition fit or an interference fit. I also learned the manufacturing processes that should be used to achieve the desired fit while maintaining the desired tolerance. For example, when I was manufacturing the pillow blocks for the car, I had to drill the holes to a very tight tolerance to create a press fit for the bushings to be fit into. To do this I used the mill and first drilled a center hole. Next I drilled a hole using a drill bit that was slightly smaller than the desired hole size. Finally, I used a reamer to ream the hole to the precise dimension needed.

ME250 also improved some of my skills that I had learned in earlier classes. Before entering ME250, I had previous experience in using the CAD program Solid Edge. Because of this, I already had a sense of how to create parts, assemblies, and drawings. I found that Solid Works was very similar to Solid Edge and thus allowed me to practice and improve upon the skills I already had.

This course also improved my teamwork skills. Due to the open-ended nature of the design problem, there were many different strategies and concepts that could be implemented. Therefore, each team member had their own views on what we should create for our machine at each step in the process. Because of this, I became better at seeing and understanding other’s ideas and also critiquing/combining several different ideas to create and even better design. I also became better at conveying my ideas to others by use of explanations and drawings.

Before this course I already had fairly decent time management skills. This course simply reiterated to me the importance of proper time management. A large part of our team’s success was due to these time management skills. Because we managed our time properly, we were able to finish the majority of our robot with a couple days to spare. This provided us with crucial testing time which allowed us to encounter problems we did not previously envision while still having time to correct these problems. One thing we did not expect was the large deflection on our planetary gearbox shaft caused by the great amount of torque needed to propel our Velcro covered wheels. If we did not allow ourselves ample time to test our machine, we would not have had time to manufacture another pillow block to fit on the end of the motor shaft to eliminate this deflection. This would have caused our planetary gearbox to fail prematurely thus rendering our machine immobile. We also found that the gears and conveyor belt wheels that were held on with epoxy were spinning on their shafts. We were able to remedy this by drilling holes and inserting set screws through the gears and into the shaft.

An area where this course could have used improvement was with the homework assignments. I felt that the requirements of needed detail in the first homework should have been more clearly stated. Also, the requirements for the FRDPARRC tables were unclear in the begging with the necessary detail needed in each step. Also, the detail of the peer review comments on the first few milestones was also unclear. For example, I got full credit for the comments on the MS where we had to come up with three strategies with no remarks from Sei Jin stating that in the future I needed to ask for more detailed comments. However, on the next milestone I had the exact same length/quality of comments on my concepts as I did for my strategies but was marked off 5 points for comments other people wrote on my concepts. I felt that this was unfair due to the fact that no specific detail level was ever stated by Sei Jin and there was no warning after the first assignment was graded that I needed to ask for more detailed comments.

I could have improved my performance in this course if I would have included I greater level of detail in my first couple assignments. However, I feel that I would have done so if the requirements were more clearly stated as I discussed in the previous paragraph.

Final Bill of Materials

Dave Huston's Individual Reflection

This was a very interesting class for me. In high school I was part of two different robotics teams so I was very excited on the first day of class when I found out we would be building ping pong ball machines. I got to do a lot of manufacturing on those teams in high school, so a lot of this class was material I had come in contact with before, but there was a lot of new material I learned as well. The importance of design and analysis, time management, and attention to detail were all important lessons I learned in ME 250 this semester.

I learned a lot about the design process. In high school, and in other projects I've done I've just rushed into the building phase, and I've seen the way a lot of those poorly planned projects turned out. Going through and deconstructing the problem, analyzing it, and designing a solution was new to me. I loved the CAD aspect, of the class, and being able to essentially create our machine entirely on a computer before ever having to pick up the building materials. I also got to see first hand how important attention to detail is, and how even one sloppy hole can throw your entire machine off. All in all the whole design and manufacturing portion of the class was invaluable.

I had heard the stories from older students about past ME 250 classes, and to be honest I was sort of expecting a blow off class, or at the very least a class that would be not too difficult. I was caught off guard by the work load, but after I got over that it became more manageable. I feel like one thing that could really improve in the class would be the manufacturing and materials lectures. As far as manufacturing goes, a lot of the things we learned are hard to understand until you actually use the machine, so some of the lectures, I felt were not super helpful, until after we had started building. The materials lectures were interesting, but I felt like a lot of what was taught was followed by, "Don't worry, you'll learn this in ME 350 or 450." I feel like it would have been more beneficial to learn more CAD, or possibly a different CAD program, rather than do all of the lectures we did. This is, however, coming from someone who spent four year in high school working on a robot team with professional engineers.

My performance could have been improved by putting forth more effort to the class at the begging of the semester. Towards the end I was averaging probably about 6 hours a day in the shop with my team, but I could have worked harder on the earlier milestones. My early designs were probably not what they could have been, had I been giving it my all earlier on.

All in all, the new ME 250 was a great class, lots of work, but a great class. It was sort of a reminder of why I am an engineering student. Seeing out team's design, which was an idea in our heads two months ago become a working machine is what I love about the whole thing.

Final Machine

The competition ready slot-bot created by Sei Jin’s Army turned out to be pretty impressive.

It started at the rear of the arena with the arm held up by a small hook formed by the welding rod. At the start of the battle, the bot would drive forward allowing the arm to drop through the center and into the arena. The rubber-band belt on the arm rotated upward pushing the balls out of the arm’s way and preventing them from jamming against the central divider.

Some of the key improvements made in the last week can be seen in the image below. There is the added ¼” aluminum plate off of the rear that helped to act as a counterweight to balance our cart and the delrin slider slightly below and in front of the bot that helped ensure it only traveled straight forward and back.

The total cost our team put into the machine was about $10 but we estimate that the total cost of materials (including those provided) was about $160.

Picture of machine


The competition proved to be an honorable day for the troops of Sei Jin’s Army.

Coming into competition day we were seeded 8th but all of us firmly believed that we had a chance to win. With the use of our intimidating scorpion attack (when we would drive to the other half of the arena and nearly tip our cart over while the arm balanced on the central divider) we upset the number one seed and made it to the final four.

Critical to this success were the Velcro wheels and the geared down planetary gearbox. The Velcro covered wheels gave us a lot of traction that helped to keep the cart on the arena surface during our scorpion attack and prevented teams from pushing us back. The geared down planetary gearbox (500:1 ratio) allowed us to power all the balls over to the other side of the arena and, in some cases, push the opponent’s bot back as well on the way there.

Before the semi-finals match, our arm’s gearbox within the arena broke leaving our belt powerless. After losing to Murphy’s Law we decided to cut the rubber-band belt off to decrease the friction from the balls. This tactic paid off in the consolation match as we successfully won 3rd place.

We were all very pleased with our performance, but at the same time were interested to see what the semi-final match would have been like with a healthy Sei Jin’s Army. Altogether, we had a great time this semester, and our hard work really paid off in the competition.