Final Post - Adrienne Lemberger

I’m going to start by saying that this was hands down the most worthwhile and fun class I have taken to date. Not everything about it was perfect, and there were more than a few times during the semester when I would not have said this was true. But at the beginning of the semester I remember thinking to myself that it would be a miracle if I could actually help build a machine that functioned the way it was intended to, and well. It’s debatable as to whether that was achieved, but it was close enough that I’m fairly impressed with my team and myself, and am very proud of our final product.

Almost every aspect of the project was a challenge in some way. Since we chose such an ambitious design, we had to spend a lot of time working numbers to even convince ourselves that it would work. And honestly, I was pretty sure it might not. There ended up being way more unknowns, incalcuables, and assumptions than I expected or felt comfortable with. But my guess is that this is usually the case with real-life engineering situations, and that I need to learn to expect and get used to it.

I also had my doubts about our ability to manufacture parts as accurately as we needed them to be to perform at the level we needed. But as I became more experienced with using the machines, my confidence level grew to point where I just assumed I could make anything as precisely as we needed. I know this isn’t true, but I made a lot of parts on a lot of machines with a pretty high success rate, and only hurt myself once.

Due in part to the fact that we chose such a complex design, we ended up spending enormous quantities of time working in the ME and 250 shops. At a certain point, it just became “If you have free time before dinner, you will be spend it in the shop.” Once I came to grips with exactly how much time it was going to take, it wasn’t as big of a deal. We did a good job planning ahead and picking a good schedule and sticking to it, which was definitely beneficial – we would have certainly struggled to even finish a poor quality version if we hadn’t. We worked a lot in the mornings when the shop wasn’t crowded, which was fantastic because we were more productive, and had easy access to Bob and Marv’s knowledge.

Most of the things that I could say I learned about teamwork I already knew on some level and sound pretty cliché. My group just happened to be fantastic, which helped reinforce for me that it is actually alright to trust other people’s ideas and decisions sometimes. In high schools this wasn’t often the case, so it has taken some work for me to feel comfortable letting other people take on huge responsibilities. And it turns out, sometimes they have better ideas than I do.

I also want to comment some on how I thought out project ended up. Squishy clearly didn’t perform the way we wanted him to. It was our choice to make him as complicated and risky as we did, but I know that we are all very happy and proud of that choice. Given that, I don’t think that there was really much we could have done about Squishy not performing very closely to how we intended. The biggest problem was that the bottom of the hopper had a very difficult time actually picking up the balls. The funny thing was that it was very successful in picking up the balls when controlled by hand and not by leadscrew, and with the balls not stacked in the slot. This meant that we couldn’t have possibly discovered that this was a problem until we had the opportunity to test in the arena, which was not until 4 work days before the due date. As soon as we were able to observe the problem, we knew exactly what we could have done differently to make it more effective (no torsion springs, less columns, closer spacing of columns/no connector piece creating column divisions, flexible/elastic openings, and more), but there wasn’t enough time to adjust anything large. This created a large wave of minor changes we had to make that compromised our ability to follow our strategy (increase leadscrew gear box ratio a lot, makes it go slower, not enough time to pick up multiple pushes of balls, or drive around the outside of the arena). However, like I said before, I’m very proud of what we ended up with. I thought we did great job of analyzing the scenario, following the design process, and making adjustments when necessary. And if we had had more time to manufacture and test the machines, I feel that our design could have been mush more successful.

There was a lot of material, and I certainly don’t understand or know how to do some things that other people in the class learned how to do much better (CAD being a main thing), but the class wouldn’t have been as good had something not been included. I would have been nice to have a greater manufacturing and testing window, but what could you take away time from?

Also, I want to say that the GSI on the whole were fantastic, very accommodating, helpful, and clearly spend an enormous amount of time making everything happen.

Anne Schwabel - Final Blog Post

Overall, ME250 was an intensive introduction to manufacturing and design of a relatively simple machine with a difficult task. This project was much more complicated than anything I have ever built before and because of that, I sometimes felt that I was put in over my head. But on the other hand, because of the large quantity of hard work and large quantity of material that we learned, it gave me a much better understanding of mechanical engineering and the manufacturing and design process. I also think taking a class like this is important to give you an idea of what is involved in some types of mechanical engineering. I have taken classes in CAD before, but this time it was very interesting to actually see the final product after it was designed on the computer. I also have always been interested in design and manufacturing and after taking this class, I hope to make it my specialization within mechanical engineering.

For the most part, my group worked really well together. Everyone worked very hard and we all were good at different parts of the project, so when we came together, we were able to get everything done. This is one of my many engineering classes that require teamwork, so all members of my team had teamwork experience which was useful. We had to make many compromises when one group member had a different idea than another group member of how a task should be accomplished. We all knew we had an ambitious project with many parts and therefore understood that we had a lot of work ahead of us for the semester. To accomplish the amount that we did in the past three months, we all had to have very good time management skills. We started early, when there were very few other teams in the shop. This was helpful because we got more individual attention when asking for advice about how to build our project and when machining the parts. We had out machine completely assembled on the Friday before it was due so we could practice using it and many any small changes necessary. We also had many meetings on the weekends to discuss what we were going to be doing next week, what changes needed to be made in the design, and when we all were going to be available to work on it. This way we could get right to work when we got to the shop during the week and we were all on the same page.

Through the lectures, I was able to learn a lot about the parts and how they were used. I was also able to learn about the design process and how to use it. I wish we could have known our project rules and materials earlier in the semester. It was hard to learn the design process when it the idea was so broad because normally there are a lot of constraints when designing a project so it felt like the entire first couple milestones were not very helpful. This way we could have starting getting reasonable ideas earlier in the semester. The lectures covered a large amount of material in a short amount of time. The CAD classes also would have been very fast for anyone that had never taken a CAD class before. I think because so much material was covered, we were not able to get as in depth on some topics as I felt we should have unless we did extra work outside of class to learn more about it. The homework often did not relate directly to the lectures and often took a long time on top of working on the project because it involved a lot of outside knowledge. I did like though being able to learn about the equipment in lecture first then being able to use it. It allowed me to use what I had learned in class towards the project which really reinforced the concepts.

Even though this class has been one of the time intensive classes I have taken at the University of Michigan, I learned a lot about design, manufacturing, teamwork, and time management. Overall enjoyed this class and am looking forward to ME350 next semester.

Final Bill of Materials

Link to Final Bill of Materials:

http://spreadsheets.google.com/ccc?key=0AofiS4ctRuXxdHBZYWEwMEpiZ0NlQjVzNWpUMWxXb1E&hl=en

Final Individual Reflection-Alec Cohen

I learned a lot in ME 250 this semester. I came into the class excited because I was really interested in using CAD to design something, and then actually build it. I wasn’t really sure what to expect because I hadn’t talked to anyone who had taken the class before, and basically I was just ready to find out what mechanical engineering was all about.

I feel like I now have a really good idea about what I have to do to complete a design project in the future. I definitely learned a lot about the Design and Manufacturing process. I now know how to go from a general strategy, to a more focused concept, to modules of a concept that each have specific roles, and finally to the smallest components that make up the modules. I learned about FRDPARRCS and how to use them in each step of the design process to define functional requirements, design parameters, etc. I also learned about fundamental design principles such as Occam’s Razor, Accuracy, Repeatability, Resolution, and St. Venant’s Principle that helped guide my team through the design process.

I now have so much more knowledge about mechanical components and structures than I previously had. I truly feel like I can look at most mechanical devices and know or give a pretty good educated guess as to how it works, why it works, and what components were used to make it work. I can pretty much say that that is all due to this class.

I now feel confident when I walk into the machine shop. When we first started working in the shop, I didn’t remember much of what was taught during the training sessions, but after working in there as much as we did, I now know how to use every machine there. I used to think of it as the place where only the upper class mechanical engineering students worked. ME 250 completely changed my view of the shop; now I feel like I belong there just as much as the ME 450 students.

I definitely learned a lot about teamwork and time management in ME 250. I ended up in a great team. We all got along, we never fought, and I think we all worked really well together. I think some reasons for this were that we always listened to everyone’s ideas, we all did our share of work, and we were all willing to work long hours on our project.

We decided near the start of the project that we were going to try to finish as early as possible in order to have time for testing. We scheduled ourselves to finish about a week or a week and a half early. After actually starting, we weren’t sure whether or not we were going to be able to finish quite that early, but in the end we still finished before we needed to. I think setting that goal of finishing earlier than needed really helped push us to work a lot, early, and in the end I think that really played to our advantage.

I honestly think the class was structured very well. All of the homework’s had to do with our project: creativity, sketching and force analysis, materials and mechanical components, a complete mechanical device (bike) and all of the components of it, how they work together, etc, and finally the motors. At the time when I was actually doing the homework’s, it didn’t seem like there was a good purpose for them. Looking back there definitely was a purpose to them, to give us small problems to solve in each of those categories because those are the types of problems we would need to solve when designing our actually machine.

I think all of the milestones also gave us a taste of what we would need to be doing for our project. Coming up with individual strategies, concepts, and modules gave us time to think about what kinds of things would actually work and what wouldn’t work. Again, it was hard for me to understand back at the start of the class when we were coming up with these individual designs the importance of thinking of different ideas and comparing them to determine the best one.

The CAD sessions and homework’s definitely helped me because I had never used CAD before, so it was really helpful to have lab time to learn about the functions of CAD and the homework’s to practice with it.

It all was definitely a lot of work, and I definitely spent the most time working on things for this class than for any other class, but I do think that it was all worth it in the end. Everything we did had a greater purpose in teaching us something useful that we could use in designing our machines. It was hard to see the bigger picture while actually doing all of the homework’s and milestones, but looking back, I can definitely see the big picture now.

Overall, I am pretty happy with my performance in the class. I think I could have probably gotten a few more points on the homework’s if I went to the office hours more, and other than that the only thing is if our machine worked a little better.

I think we had a good strategy of going for the heavy balls, and I think it was good that our machine was so different from everyone else’s. One thing I think we could have done better was to take our idea of a “hopper” (the cage that the balls went into) and come up with different concepts for it. If we had came up with multiple ideas for what exactly was on the bottom of the cage that allowed the balls to enter into the cage but prevented them from falling out of the cage, and then compared them to determine which would work the best, I think we might have had more success in the competition.

Our machine moved the way we intended for it to move; the leadscrew drove the scissor arms really well, and the cart was able to drive back and forth. It was just the hopper, specifically that the hopper was split up into rigid columns, so the balls in the arena didn’t perfectly line up with the columns in the hopper. We thought the hopper would move the balls around until they did line up with the hopper columns.

When I tried picking up balls with just the scissor linkage-hopper mechanism (before it was attached to the cart) by physically lowering it into the slot and pushing on the balls, I was able to fill up the hopper by wiggling the hopper around until the balls lined up in the columns. Once the hopper was attached to the cart, however, I wasn’t able to wiggle the hopper around quite as much (all I could do was move the cart back and forth a little). This worked in the seeding round, but it did not work in the actual competition.

Even after these mishaps with our machine, I still am very proud of it and of our team, and I am really glad that I took this class. It was a great experience and I learned a lot that will definitely help me in the future.

Individual Reflection - Michelle Brady

What I learned:

Design and Manufacturing:
I learned how to use a laser cutter, band saw, drill press and lathe this semester. It was really great to learn how to use these machines and get hands on experience. I learned that no matter how hard we try and how many steps we take to be precise, there are more errors than we expect, but most of the time it works out. I also learned that when designing parts, we should make things as close to a sixteenth of an inch or any marker on a ruler for something we have to measure out. It makes cutting and drilling parts much easier that way and it is easier to be accurate. I also learned that sometimes when in the early stages of the designing process, we have to work together more than the later stages so that everyone knows (or has a good idea) about what the others are doing.

Teamwork:
I thought I knew a lot about teamwork from other classes and societies, but I still learned a lot this semester. I learned the importance of making sure that everyone is on the same page and keeping each other up to date. We had a team email address and ctools page which really helped us to share information and keep each other updated when we weren't working in the same place. Google docs also helped in that we could all write in the same document without having to upload files continuously. We learned how important it was to know our schedule and our team members' schedules for the upcoming week so we could plan what we needed to, could, and wanted to accomplish that week in the shop and if we needed to sign up for any machine times. I also learned to compromise, which was not a strong suit of mine. With four people working together, we did not always have the same idea about which was the “right” way or the best way.

Time Management:
Our team really had to work on time management since our project had many components and we wanted a good amount of time to practice. We learned that most of our early expectations of how long parts would take were off. They either took less time (rare case) or more time than we had originally planned. I learned start early and work often especially in the day for the shop. When we needed help or had questions it was easier to get it earlier in the week and the day and Friday afternoon, and it was emptier then too. Therefore, we tried to schedule our work more at those times (it worked out that those times were good for us to work together) and we scheduled our other class work around those times.

How the course could be improved:
~Set the rules and give out the kit earlier in the semester - we wasted a lot of time by starting basically from scratch.
~Give more feedback on milestones and CAD assignments - I never knew how I was doing on CAD while there was still time to change the way it was submitted.
~Space out the homework, MS, and CAD assignments better at the beginning of the semester.
~Allow the teams that had milestones done ahead of time to submit them early - there were a couple times we had to wait because we needed more information before we could continue which may have set us back.
~Give out the grading criteria for CAD, milestones and homework ahead of time so we know how we can do well.
~Do the lab safety closer to the time that we will actually enter the shop - it was hard to remember everything that we had been told over a month before

How my performance could have been improved:
~I could have done better on some of the assignments had I known more about what was expected of me before submitting later assignments.
~Practicing more on CAD.
~Taken notes after each of the lab safety classes.

Final Team Blog

We decided to name our machine Squishy so any referral to our machine will be as Squishy. The only thing we have changed this week is the appearance, we added glitter to the top of Squishy, stickers to the sides, and each of us decorated a vertical post with our name on it.

We also made our video this week. It included videos and pictures of us making Squishy in the 250 shop and the machine shop.

Squishy's final operations were: the leadscrew moved the scissor arm across the scissor arm base as we designed it, the pulley helped the leadscrew pull the hopper back up, the hopper picked up the balls, the wheels moved the cart forward. Our initial plan was to pick up the heavy balls, but after testing, that was not possible. The hopper could not get past the first round of balls, so we started the hopper closer to the halfway point to use the defense of blocking part of our slot while still trying to pick up the balls there. We also had to change our original idea from driving the cart around the arena to driving "straight" forward since our wheels would not turn the cart sharp enough to make the movements necessary.

When we ran Squishy, we started the hopper in the arena with the hopper a couple inches into the slot. We had to position the cart very carefully so that the scissor arms were vertical. Once the competition started, we pushed down on the first row of balls using the leadscrew. After we made contact with the balls, we wiggled the cart back and forth to get the balls to line up in the hopper as best we could. We continued to push down on the balls until they were high enough in the hopper that the springs released. This would generally take most of our time so after the first row of balls, we would use the leadscrew and pulley to pull the hopper back up and drive the cart to the other side.

Significant changes we made along the way:
~added a pulley to help the leadscrew pick up the hopper
~added the side bar after the pulley to keep the hopper from hitting the wheels
~changed all the gear ratios to higher than initial settings
~added string to the spring flaps at the bottom of the hopper
~decided to thread the hopper
~added notches in scissor arm base so the caps would fit
~made L pieces to attach the vertical supports to the cart and horizontal base

Good decisions we made:
~Being different - no scooping arm
~Buying the caps for the scissor arms - not using eclips/ turning notches for them
~Starting early - consistently working in the morning
~Using the laser cutter when possible
~DECORATING SQUISHY!!!