Final Reflection - Ryan

This class was both the most interesting and time consuming class I had this semester. The lessons I learned while participating in this program I believe were the most useful in terms of my development as both a team player and a professional. I aim to take these lessons not only into later design classes but also into internships and other team projects.

One key concept I learned about in this class was the techniques and concerns regarding the manufacturing of a design. I not only was exposed to the shop tools (mill, lathe, laser cutter, water jet), but I was also exposed to the issues an engineer must consider when developing a part. The concept of quantifying the quality of manufacturing (surface finish, flatness, geometric and scalar tolerances) were very interesting to me, and brought me to appreciate the amount of thought that must be put into the manufacturing of simple every day objects (particularly the quality).

This class heavily trained me in time management. Due to the amount of work that had to be put into the project, as well as the workload in my other classes, time became my most valuable (and most scarce) resource. Utilizing time and resources became critical in the execution of completing the project. One thing I learned very quickly is that the distribution of time between manufacturing and design was critical. Time was spent more efficiently when it was put into quality design work rather than put into engineering. This class demonstrated to me quite clearly that the initial investment in time for design is very rewarding in the future.

Teamwork was vital to the completion and success of the project. This class taught me a great deal in the value of teamwork in the completion of a project as well as the skills necessary to effectively communicate to each member of the team. Communication was clearly one of the most important skills needed in a positive team environment, and I believe all teams recognized this over the course of the class. One challenge that our team faced was the difficulty of meeting other members. Due to classes, extracurricular activities, homework, exams, and logistics it was difficult for the team to meet often for useful periods of time. Tasks had to be delegated between members in order to complete things on time. However this delegation was both uneven and inefficient, which led to delays in our schedule.

I believe my performance in this class could have been improved if I had a less demanding schedule. I had difficulty coping with my course load this semester and budgeting my time in order to ensure my success in all my classes. I have no regrets with the amount of effort I had put into this class. If anything, I have learned that I should have been less generous with the amount of time I allotted to the class. That way the time I would have spent would have been used much more efficiently.

There are two major concerns I had with this class that I felt should be addressed. First, I believe that the design process and team selection should be done earlier so that more time can be used by the teams to properly design their machines. I believe the development of the manufacturing design took the most time and required the greatest amount of effort. By giving teams this extra time, they may have the opportunity to properly design their machines and have them reviewed by the course instructors in proper detail. The other concern I had was the difficulty in interpreting the expectations for each assignment. It was difficult for me to prepare (and therefore determine how much time to invest) for assignments in this class. This issue I feel will be minimized as the course is refined over more years.

Final Reflection - Annie

Going into ME 250, I did not know what to expect.  I am a senior in Chemical Engineering, which I felt gave me some advantages and disadvantages in this class.  The design process was familiar to me, if only as a way of solving problems.  Many of my classes had prepared me to think of a problem in this way.  Another advantage I had as a senior in this class was the work ethic instilled in me from four years of engineering education.  With my full course load this semester, I could not procrastinate on any of my classes if I wanted to get all of my work done.  For this class in particular, I liked to get the homework done well before the deadline so that I would not scramble at the end to get it done by the deadline.  Some of my other course work helped in some of the assignments as well.  I am taking a material science engineering class on materials and manufacturing, so the lectures that covered materials selection were somewhat of a review.

On the other hand, the manufacturing process was completely new.  The only time I had ever used power tools at all was volunteering for Habitat for Humanity.  I was initially rather timid using the machine shop.  Once I figured out how to use the machines, I was more willing to attempt manufacturing.  Also, many of the details of the physics concepts were rather fuzzy to me.  I have not taking physics since my sophomore year of college, and had given away my textbook from the class.  This made some of the analysis parts of the homework and the design process more difficult.

As teamwork goes, this required more work with a team than any other class that I have taken.  One thing that I particularly learned this semester was how to rely on my team when I could not help them with the work we needed to do.  My ChemE lab class had deadlines very close to the ME 250 deadlines, so I could not always help with the manufacturing as much as I would like.  Between my groups for ChemE and ME, I was able to help with both projects and feel satisfied with the end product.

One critique I have of the course was that the initial design process seemed removed from the actual manufacturing.  Aside from the descriptions given on the materials sheet, we were not given a good idea of what we could use in our machine.  In my case, the strategies and concepts from MS1 and MS2 were not anything near what would be possible with the materials we had.  Also, we were not given the kit until the week before the design review, which made making our overall team design difficult.  I found it much easier to design the machine after I had parts in my hand and could see how they would interact.

To improve my own performance in the class, I would have spent more time reviewing the physics concepts from Physics 140.  I lost some points on the exam and on a couple of the homework assignments from these, and I could have gotten these points if I had a better grasp of the concepts.

I have to say that one of the best parts of this class at the moment is that it is done once I submit this reflection.  With this class and my ChemE lab class done, I only have two exams left, which gives me a lot more time to study.

It was also exciting to see our machines compete.  I have a ridiculously competitive streak, so it was really exciting when we won our first round.

Final Reflection-Lauren

As a transfer student from Spelman College in Atlanta I had taken courses on Engineering Design but I never had the opportunity to actually design any of the things we thought up. This course reminded me why I made the decision to transfer to the University of Michigan. The amount of resources this school has to offer was very well demonstrated within the requirements of this course. This course taught me how to apply many things I learned in the past and that I actually have the skills to become a Mechanical Engineer.

I had experienced working in groups before in the past but never on a project as demanding as this. Our team was a diverse group of people, including Annie a Chemical Engineering major. We all lived on different parts of campus and had conflicting class schedules but somehow we made it all work to create a working machine. Working on a team is often difficult when people have different ideas of how things should be done but we didn’t have many problems with that. I was also grateful to be on an understanding team. In the middle of manufacturing of our machine I came down with the flu and couldn’t be involved in much of the building, my team was very understanding of that fact and accepted the work I did before I was sick and after I returned. This experience involved a lot of sacrifice and at times truly tested my commitment to the class. At the end I feel I learned to appreciate what each person brought to the table and I also got a chance to get to know three people I probably wouldn’t have met otherwise.

The amount of assignments early on in the course was a good preparation for the time I would have to put into creating the machine. Time management wasn’t really an issue with us as a team because all of us had the same mindset of trying to finish the machine and each group assignment as early as possible. I am taking four engineering classes this semester and this one probably took up most of my time. I have to admit it wasn’t an easy thing to do but once we started working on it, everything fell into place.

From what I’ve heard from former ME 250 students this course was already a great improvement from semesters past, however it was not perfect. The lectures covered a lot of material that was relevant to many machines but often times it was too much material given at one time which made it difficult to understand. I also appreciate the fact that we had to do physics calculations before we built our machines; however some of the physics knowledge expected of us in homework and on the exam was more than the prerequisites provided. I could have improved my performance in this class by devoting more time to it in the beginning instead of just trying to get assignments out of the way.

Final Reflection-Anthony

Individual Reflection

What I Learned in ME250?

Design and Manufacturing

Coming into ME250, I knew very little on the topics of manufacturing and design except what I had learned in my previous engineering courses. With this, I was learning something new at almost every lecture. I believe the most important lectures were the design process, ideas and analysis, and design principles. These “big picture” ideas helped a great deal in our project and they could be applied in many aspects of life as well. Lectures 7-11 helped to lay a solid foundation in mechanical components that I can hopefully use in subsequent courses.

Teamwork

My experience in ME250 has taught as well as reinforced some notions I have about teams. I learned that you have to be able to utilize the skills that different members of your team have. If a team in not diverse in the skills that it possesses, then the team will struggle. One idea that I have had about teams involves the time a person commits to the course. One wants to find team members that will devote a fair amount of time to a course. This may mean steering away from people that have a heavy course load or additional activities.

Time Management

Procrastination is a terrible habit to have. Waiting until the last minute to manufacture a part or create a drawing will eventually lead to trouble. Following a schedule is very important. When different obstacles arise, a team can adapt if there is time. One of my favorite professors Jason Daida once stated the phrase “three-day horizon”. A person who has a three-day horizon looks ahead and is never left with trouble at the end.

How the course could be improved?

I enjoyed this course very much, but I do believe that there could be some improvements. To begin, I found the descriptions of some of the earlier milestones to be vague; specifically, the milestones that dealt with creating concepts and strategies. I did not completely understand the task of the first milestone, and I ended up formulating strategies instead of concepts. Because of this, I was one step ahead for the first few milestones. Secondly, I believe that we should have received our kits earlier. It was difficult to create feasible strategies without knowing what types of materials, electrical, and mechanical components we would be given. In the end, most of us had to scrap our initial ideas and start over with a new strategy. Sometimes this is how engineering is in the real world. I found the workload to be appropriate, and the shop hours were very convenient.

How could I have improved my performance in the course?

I performed fairly well in the course, but there is always room for improvement. Firstly, I could have spent more time preparing for the exam. I did not perform as well as I would have liked, and I believe that I may have looked past it a little after the percentage of weight given to it was changed from 20% to 12%. Specifically, I was not prepared for the different calculations in the second part of the exam. I was fairly prepared however for the big picture engineering question which was weighted fairly heavily. Secondly, I could have spent more time working on the project. With our design being fairly simple, our team felt that we would be able to finish all manufacturing with at least a week left at the end to test it. Different “obstacles” came up that extended our schedule, and we did not finish manufacturing with much time left to test. Specifically, the gear ratio that we used in our motor was not ideal. My calculation of arm speed across the slot as not correct, and this was evident in our first test. We ending up switching the motor from 400:1 to 25:1 with only a few days left until the Design Expo. We also utilized our second planetary motor, which we did not plan on in our initial designs.

Comments

I would have liked to see the GSIs and/or Professor create a slot-bot ;)

Thanks for a great semester!

Final Wrap-up

Hello!

The competition was on Thursday.  We finished our machine on Tuesday night.  We had some slight alterations from our original plan that we presented in the Design Review.  After taking a look at our competition, we saw that there were no teams that were going for the bin at all, so we decided to scrap the bin blocking module we were going to have.  Our final machine ended up consisting of a leadscrew, arm, motor housing box, and a support for the end of the lead screw.  After our seeding round, we realized that the arm got jammed when the balls piled up, so we added a motor on the support at the end of the lead screw to pull up the arm.  Here's a picture of our machine assembled in the slot:

One major problem we had that we didn't realize until the competition was the string we used to pull up the arm was not strong enough.  When we were making it, the kevlar thread was out, so we used kite string instead.  In both of the competition runs we did on Thursday, this thread ended up breaking, so we had to replace it after our first run.

Another improvement we would have made would have been to use the external gears to give more torque to our arm.  As it is, our arm had enough torque to push the balls, but not when they got jammed.

Here's a picture of our arm in action:

Our strategy for the competition ended up being get a ball over the center line and hold the arm there to block.  It worked for the first round.  We got one ball over and were able to hold the arm there to prevent the other team from scoring any.

Thanks for a great semester!

Final Bill of Materials

Item-Supplier-Function or Use

1. 3/8" Steel Threaded Rod-Crib-Leadscrew
2. 1" Diameter PVC Rod-Kit-Telescoping Arm
   
3. 3/4" Diameter PVC Rod-Kit-Telescoping Arm
   
4. 1/4" Diameter Aluminum Rod-Kit-Telescoping Arm and Vertical Motor Shaft
5. 1/8" Diameter Steel Rod-*Home-Telescoping Arm
   
6. 1" Diameter Round Aluminum Stock-Machine Shop-Telescoping Arm
7. 1/4" Flanged SS Bearings(Quantity-3)-Kit+Crib-Horizontal Motor+Vertical Motor
   
8. 1/4" Flanged Bushing-Kit-Vertical Motor
   
9. 1/8" 90 Degree Aluminum Angle-Kit-Pillow Blocks
   
10. 12" Velcro-Kit-Base and Motor Box
    
11. Electrical Tape-*Home+Crib-Bottom Flap
    
12. Planetary Gearbox Kit(Quantity-2)-Kit-Motors
13. 1/4" E-clips(Quantity-2)-Kit-Telescoping Arm
    
14. 1/8" E-clips(Quantity-2)-Machine Shop-Telescoping Arm
    
15. 1.5"x1.5" Aluminum Square Stock-Machine Shop-Base for Motor
    
16. 1/2" Plywood-*Home-Motor Box
    
17. #6 Machine Screws-Machine Shop+Crib-Motors
18. #6 Wood Screws-*Home-Motors
19. #10 Wood Screws-*Home-Motors+Motor Box
20. 1/4" Hex Nuts-Crib-Base, L-Brackets
    
21. 3/8" Plastic Tubing-*Home-Wires
22. Kite String-*Home-Pin Device
    
23. Needle-*Home-Pin Device
    
24. Buna-N Sheet-Kit-Arena Protection
    
25. Wire-Crib-Motors
26. 1/16" Aluminum Plate-Kit-Motor Box, L-Brackets
    
27. Banana Nuts-Crib-Motors
28. 3.75"x9" Plexiglass-*Home-Motor Box

Note-*Home indicates an item that was supplied from a team member's household. The price is negligible.

Competition Day

Hi there!

Today is the big day!  We're competing in the Duderstadt Gallery from 1:30 to 3:00!  Our seeding round could have gone a little bit better (our arm popped off of the nut due to some miscommunication), but we ended up about middle of the pack, seed-wise.  We'll see how it goes competing against the other teams.  Our machine seems to block some of the other machines from what I see, so hopefully we'll do pretty well.

As for final manufacturing, we added another motor to pull up on the arm when it reaches the middle of the arena.  This definitely helps with the scoring.  We also changed the leadscrew from the 1/4" aluminum to the 3/8" mild steel, which is much more robust and better suited for our purpose.

Good luck to all the other teams!

Video Clip

Progress Report/To do list

I completely forgot that we needed to have an updated on the blog by Monday, so here's my (slightly late) to-do list.  Luckily, my favorite thing to do for this class is to make to-do lists, so I have one from Monday, as well as our updated one (as of Thrusday 12/3).

On Monday, what we had done was our MCM.  Here's our to-do from then:

- Find a way to connect the arm to the screw
- Assemble motor box
- Create support for the "other" end of the screw
- Evaluate feasibility of bin flap
- Figure out motor coupling
- Manufacture a way to make the arm telescop

As the week went on, we decided that the bin cover from our original design might not be worth the effort to make.  Most of the machines we have seen have been the "arm in the slot" variety.  The only type of machine that would have a good chance of getting a ball in the slot is one that had a flinging motion over the whole apparatus.  We decided that the only way we'd really do that is if we had an excess of time sometime between then and Monday (which it turns out we won't have).  So we had simplify the design a little bit to eliminate the flap.

Here's what our plan for the week was:

Monday - During lab - create "nut" for attaching screw and arm.  Tap and make sure it runs on the screw
Tuesday - Cut plywood and plan motor box
Wednesday - Manufacture screw end
Thursday - Make sure whole assembly fits in the arena
Friday - Tie up all the loose ends and test

So for now, our loose ends seem to be:

- Build the motor box (leaving room for battery pack, remote control, etc)

- Assemble the end of screw

- Telescoping motion creater (pin of some variety)

- Way to pull up the flap and arm at the end of the screw (we have some ideas)

- Assemble remote control

The good news is that our cars basically block a lot of the "car" variety of machines.  Most of them only move with the slot's direction and won't be able to get around the screw.  We just need to make sure the screw doesn't get misaligned if they run into us.

Hopefully we will get this done by Friday evening, or else we'll have an early morning on Monday to make sure it's all done by 10:30.

One week until the design expo!

The end of the semester looks a whole lot closer from this side of Thanksgiving!  We demonstrated our Most Critical Module (the arm) last week for Jean, as well as showed the remaining engineering.  This week, we've worked on making the rest of the components for the machine.  By tomorrow, we should have a testable machine, so we can run the arm though the arena and see what happens, and make sure everything is working for our machine demo on Monday.

I finally found my camera, so we finally have pictures of our machine in the arena!

Our most critical module came out without too many difficulties.  Machining the PVC was more difficult than we expected, but now that we're done, it works just like we planned.  We now have a lot of experience using the lathe.  We made quite a few little aluminum pins to hold everything together.  I decided during lab that the arm needed some spicing up, so I decorated it with permanent marker.

For the leadscrew to arm connector, we decided to make our own "nut" of a sort to run on the screw.  We used aluminum stock and the lathe to create something that would fit tightly in the PVC, and then drilled and tapped a hole.  Once we had that, it took a couple of times running the connector through the screw to get rid of all the debris left over from the manufacturing, but now the screw runs with no interference.

One of the biggest discussions we had was how to connect the motor to leadscrew.  Anthony came up with an awesome flexible coupling made from CPVC that clamps down on both the screw and the motor shaft, and slots in the middle to allow for some misalignment.  We decided this would work better than the tube we used for the motor in HW 5, as it is much more robust.

I had planned on testing it a little bit this morning, but due to a complication (one of the wires on the motor fell off, and I didn't have time to put it back on and run a couple tests), I wasn't able to.  Hopefully we'll run it either today or tomorrow.  Just a few more components to fabricate, and then we'll have a completed machine!