ME 250 Individual Reflection - Jonah Shapiro

I did not know entirely what to expect when I first started ME 250 at the beginning of the semester. And as I end the semester, I am still not quite sure what to make of it. There were many ups and downs throughout the course of this very unique and challenging class. I know I have come a long way from where I started and have learned significantly more in this class thant I have in other classes. For one, I had no idea how much preparation and time went into the design process. I learned a lot about starting with a broad, unfocused idea and narrowing it down through the use of the group discussion and other tools, such as FRDPARRC tables, and coming out of the process with a focused and specific goal.

Any time you have the chance to work with a team on a project it ias always beneficial. Having had some real world job experience over the summer has shown me that being able to effectively work as a part of a team is crucial to a successful project both in and out of school. Even from the very beginning with the video of the team designing a shopping cart, teamwork was one of the main points emphasized in the class and one that I feel is the most valuable.

Part of the class that could be improved is the homework assignments during the first half of the semester. They seemed to be far too specific on their particular topics and I did not find any of the information used on them to be helpful at all during the project. All the design homework was good because it showed us how to hone our ides and how to help critique others, but any information I got from figuring out how hard a weightlifter could push down on a unicycle pedal was useless when it came ti the final project or for any other part of the class. I recognized a lot of the equations from other engineering and physics classes, and those assignments would have fit perfectly in those classes. But trying to put them into a design class that has no prerequisites and included studetns from other engineering disciplines besides mechanical seemed unfair and unnecessary.

Also, the exam format should be greatly shortened. I do not see anything to be gained in forcing students to sprint through several, long problems and I do not feel that this could possibly give an accurate representation of the students' knowledge, esecially when they can not even attempt each problem due to time constraints. Using a select few questions and allowing for adequate time to finish the entire exam would give you a much better idea of the students' capabilities.

I feel very proud of the work I have done in the class and the work done by my team. I feel like I fully aplied myself during the labs and shop times and would not change my performance in that aspect of the class. I could have, however, paid more attention during the lectures and tried harder to take more away from them, as opposed to biding my time until they were finished. A lot of times I found myself returnig the the lecture slides to look something up, when I could have learned it the first time I saw it had I been paying more attention.

Once the class moved beyond the tedious and time-consuming assignments and I got used to the heavy workload and late nights spent on north campus working on the project, I truly enjoyed the class. I loved being able to actually make something and get to see it move and compete against other machines. I imagine it to be much more satisfying than making a wooden cup holder shaped like a toilet, such as in previous ME 250 classes. And while I was at first envious of them for not getting such a difficult and demanding project, I am extremely glad that we got the assignment that we did.

ME 250 Individual Reflection - Breana Siljander

My feelings towards ME250 are bittersweet now that the competition is over and our team finally has a chance to catch our breath, and perhaps spend some more time in our other classes. I leave this class with no regrets; I cannot emphasize enough how much I have learned about the design process and manufacturing this semester. At the start of ME250, I had never used a machine much less even been in a machine shop; the same goes for making CAD models and drawings. These tasks seem so simple now and I feel more than adequately prepared for a future design and manufacturing class.

Besides the skills necessary for design and manufacturing, the lessons I have learned in teamwork and time management are probably even more valuable. Because of the big time requirement of ME250, I had much less time to spend on my other classes than I had anticipated. Although the task of designing and manufacturing a machine in a month’s time seemed daunting and unrealistic, it had to be done so we made it happen. We had a few bumps in the road along the way, but the schedule we were required to maintain helped us stay on task and meet our deadlines. This is where teamwork played a giant role; without team unity, I feel we probably would not have accomplished as much as we did. ME250 has shown me the true strength of working in a team. Members of a team may have different ideas and personalities, but once the strengths of each member are brought together, so much can be accomplished.

The homework assignments for this class seemed well beyond our skill level and covered topics that were not discussed in lecture. Many of the requirements for assignments were also unclear and the grading quite ambiguous. While the lectures covered a massive amount of material, I feel the information would have been more useful if there was less depth and more focus on how the concepts would be used for our design project. Some of the topics covered in homework at the beginning of the semester were concepts I learned months later in my ME211 course. The exam was too long and I feel would have been better situated if we took it after we had done some manufacturing. The FRDPARRCs, although tedious, were an excellent way to get us thinking about our design. However, they would have been more beneficial if the rules and kit contents for the competition were given much sooner. Many of my initial designs were thrown out because they violated some rules that were nonexistent when we were designing.

The biggest struggle for me was my exam performance. Time was probably my biggest issue as I wasn’t sure how to allot my time for each problem. I also felt very inexperienced with the manufacturing questions on the exam because all the processes were very theoretical to me (we hadn’t yet done any manufacturing).

Overall, I am thoroughly satisfied with this class. If I could change one thing, I would throw out the homework sets because they did not benefit me in any way. This class was a giant leap from the previous terms of ME250 where their projects consisted of making static objects. I often imagined how nice it would be to have a project as simple as that; however, I am much happier with my situation because designing our dynamic machine was undoubtedly more exciting to make and the manufacturing and assembly was fun once we had a control of the concepts.

Bill of Materials

Below is the link for our final bill of materials. Also included in the document is our trade summary and our purchased list.

http://bit.ly/4u5CTj

ME 250 Individual Reflection - Mark Sprague

Overall, ME 250 has been a positive experience for me. Although it was more work than I expected given what I had heard about the course, I also learned quite a bit more than I expected to. One crucial thing I learned was how to approach the design process. Going through the strategies, concepts, modules and parts that we were required to in order to design our machine helped me understand how to start with a very wide brush on a design and wait to work on the final details. Before this class, I would have started trying to design individual parts before I had figured out what the goal of the entire machine would be. Another thing I learned is that it is important to have everything that a part interacts with engineered before you manufacture it. For example, our most critical module manufacturing was due at the same time as the engineering for the rest of our machine. While we were designing the rest of our machine, we ran into instances where we wished we had done something slightly differently on the arm (which was our most critical module).

I also learned quite a bit about team work. I learned that trying to have four people work on the same thing at once doesn’t work too well. It is much better to split up and work alone or in pairs, then bring the work back to the entire team to evaluate and make necessary changes. It wasn’t necessary to have all four of us show up to the machine shop at a given time for manufacturing either. Only 1 person is necessary to run the machines and a second one can be helpful for fetching tools and such, but with 3 of 4 people present, some people end up not doing anything.

ME 250 also helped me to work on my time management skills. In this class, I wasn’t able to do work whenever I wanted as I have become accustomed to in my other classes. Work needed to be done with my team or in the lab, and that required me working at certain hours and getting a set amount of work done within that time.

One thing I think could be improved upon in the course would be to adjust the time frame of the project. I think it would have been beneficial to have started manufacturing a week earlier than we did, and have an extra week in between the most critical module due date and the date we needed to demonstrate a working machine. There was really only one working week in between those two deadlines, and there was still quite a bit of work to do between the most critical module and the working machine for our team.
Another thing that I think could be improved would be more CAD instruction. I felt that the tutorials went very fast and were very hard to follow. I had to go through them on my own afterwards and I didn’t quite understand it all. I think I would have understood better if the tutorials had gone slower and what was being done was explained clearly. One problem I would have would be missing where the GSI had clicked to get to an option, then spending five minutes looking for it and by the time I found it being very far behind. I think one way this could be improved would be to make narrated videos of the CAD tutorials showing the screen so the student could pause and go back if they missed something. This would be supplemental, not a replacement for the CAD instruction by the GSI.

Also, another thing that could be improved in the course would be to have a more defined problem at the beginning of the class. For example, it would have been very nice if the rules and the specifications were available before we started the brainstorming phase. I think a lot more teams would have used the fixed motor had specifications been released at the beginning of the project.

One way I could have improved my performance in the course would have been to put more time into the initial design phases. I viewed them as not being very important because I hadn’t met up with my team yet, however, I feel if I had put more work into this stage of the class, I could have come up with some better ideas for how to solve the problem.

Mark Bliss ME250 Individual Reflection

This past semester has been an interesting experience in ME250. I learned quite a bit more than I had expected to. I had never been shown what exactly a design process entails, broken down into components and explained step-by-step. I learned that it is important to start with broad, even crazy, ideas and then narrow those down to a single concept and design modules and components from there. I also learned how to work effectively within a team and to make a schedule and distribute the work load to manage our time and meet our deadlines. Over the course of the manufacturing process I became pretty proficient in using the lathe and mill to quickly machine material to make the desired parts.

Overall, I enjoyed this course and learned a lot from it. I thought the design process we had to go through was very boring, for the most part, but it was much better once we were able to start manufacturing and see our designs being made into actual parts. I liked this project because there ended up being a lot of cool designs and it was especially fun competing against other teams. That being said, I think there is a lot that could be done to improve the class.

I don't know about other students who have been in the ME program at UMich their entire collegiate careers, but as a transfer student I was pretty overwhelmed right off the bat in this class. I had never gone through a design process, nor undertaken a project, like this in any of my previous classes so everything in this class was all very new to me (except for machine shop work). I feel there was WAY too much crammed into the first few weeks with the lecture homeworks, CAD assignments, and design book assignments (3 separate assignments due per week!). Granted, had these assignments been explained better I don't think the work load would have been near as bad and much more manageable. I was almost continuously confused when working on these assignments due to unclear directions, especially lecture homeworks. While the lecture homework may very well have contained "basic high school level physics" I felt like it was not in at least one assignment. It was certainly nothing I had learned in high school and still difficult to do after having taken 3 years of college physics classes, even with help in the recitations. Also, the prolonged delay in the returning of these homework assignments (several weeks) adversely affected my performance and efficiency in doing later assignments because I had no idea of what the grader's expectations were for our responses. Another problem I encountered was not being able to physically see and look through our kit contents before/while designing our machine. It made it much more difficult to visually picture what we could/were limited to do with the materials we were to be given, but I know this issue will not be a problem for future classes because the kits have already been put together.

After getting all this off my chest, I would like to say that I completely understand that we were almost inevitably going to encounter many of these issues because this class had been completely changed from previous classes. However, I still feel that some of them, such as the very lengthy delay in returning homework, could have been avoided.

In regards to my personal performance in the class, I think I have done very well on almost everything up to this point. The only major thing I could have improved on, and wished I did better on, was the exam. I think my problem was that I did not realize how fast the time was going by and so I spent way too much time on certain parts of the exam instead of hurrying through them so I could get to other parts. This is really my only grade in the class that I am truly disappointed in.

In closing, I did enjoy this class and the project but feel it was pretty advanced for students who had had little to no previous design and manufacturing experience. I also think that there was way too much crammed into the beginning of the semester, which caused us to spend much more time in the shop during the fairly short manufacturing period. The main things I would change with the class is to take out some of the assignments in the first several weeks (ideally lecture homeworks because they were the most confusing and didn't seem to have much, if anything, to do with what we did later in the semester anyway), and start manufacturing earlier in the semester so students won't have to spend so much time in the shop to get their machine done in time (I probably averaged at least 15-20 hours per week in just the 250 and ME machine shops). I am excited to see what designs future students will come up with and definitely will not miss the ME250 competition at Tech Day next year.

-Mark Bliss

Testing Process

On Friday night we were able to briefly test our machine in the arena. We were very pleased to see how well our scoop worked and that we had sufficient torque to rotate the arm even with several ping pongs on top of it. Our machine was also able to drive back and forth with ease on the top table of the arena. We encountered only one issue while testing (an axle was loose in one of the sun gears) which was quickly remedied. We should only need a few slight modifications before our machine is ready for competition.

During the three hours of testing this coming week, we plan to all take turns controlling the car in the arena. Based on our individual performances, we will as a group pick the person who will control our machine during the seeding and competition processes.

Machine Completed!

We finally finished our machine late Friday evening. Sei Jin was awesome enough to stay longer to let us complete our machine and tweak it some so it would be working for MS9 tomorrow (Monday). After finishing the MCM, we had to manufacture and put together the parts for the chassis. We used a 1/2" thick PVC plate for the base plate of our chassis. We used the waterjet to cut the plate to the shape we wanted and make our clearance holes for our pillow blocks and front "bumper" piece (90 degree angle stock).

To make our pillow blocks we used the new 1/4" angle stock that recently came in. We cut it to length on the band saw and then used the mill to precisely drill the holes in them. We used a V drill bit as suggested in the class slides for the bushing holes and a 31/64" drill bit followed by a .4998" reamer for the bearing holes.

Here are some pictures of our "finished machine" (without some minor modifications we may make in the next couple days):

Most Critical Module Complete. All Engineering Done

Last week, we finished the manufacturing and assembly of our most critical module, the arm. The remaining pieces to be manufactured were the front plate and the PVC tube arm section. The front plate was water jetted out of a 1/16 in thick sheet of aluminum. The PVC arm section was made primarily using the band saw. Originally, we had planned to use the mill, however, we were told during manufacturing that since it was hollow, the mill would not be a good option as the PVC would move quite a bit during milling.

We made a slight change to our most critical module related to the fasteners. Instead of using the metal bolts we had planned to use to attach the front plate to the arm section, we used plastic fasteners instead. These are lighter and will hopefully allow our machine to operate better. We left one metal fastener where the PVC plug meets the PVC tube to insure that the arm stays together.

Also this week, we finished the engineering of the rest of our machine. In this up and coming week, we have quite a few things to get done. First, we need to cut out the base of our car. We plan on doing this on the water jet machine and manufacturing it out of a 1/2 in PVC plate. Next, we need to manufacture our pillow blocks. We have a total of 12 pillow blocks to manufacture. They will be manufactured out of 1/8 in L-stock. These will take the majority of our time this week. We also need to manufacture 2 axles. One will be for the front wheels and the other will be for the rear wheels. Due to a shortage in supplies, we had to design each axle slightly differently. the back will be a 1/4 in diameter aluminum rod while the other will be a 3/8 in diameter aluminum rod turned down to 1/4 for where it meets the bushings. After that manufacturing is complete, we need to hook up both of our motors to the rest of the system. We have one motor that will be connected to a worm gear box to run the arm and we plan of using a planetary gear box to move the car forward and backwards.

Here are a couple of Solid Works renderings of our completed design:

Calendar

First Three Parts

This week our team manufactured three parts of our Most Critical Module, which is the scoop arm of our machine. The three parts we made were the arm axle, scoop, and a plug used to secure the scoop to the bottom of the arm.

The arm axle was manufactured primarily on the lathe from the 0.5" x 0.5" Aluminum square stock. We started by facing off the end to smooth it out and make it easier to measure. We then took that end of the rod down to a circular cross-section with a 0.25" diameter. Next, we used the band saw to cut the rod to roughly the dimension of our part. We then faced the end off again to give a smooth finish and to give the piece the required length. We once again took the end down to a 0.25" diameter. We then added grooves one each side for e-clips to fit into in order to prevent axial movement of our arm when in use. The next step was to use the mill to drill two holes in the center part of the axle for screws that will be used to secure our arm on the axle. Once this was completed, the final step was tapping each hole.

The scoop was done on the mill and band saw using the 0.25" thick Aluminum plate. The band saw was initially used to cut out a section of the plate slightly larger than the final dimensions of our piece. The mill was then used to square all the corners and ensure opposite sides were parallel to each other. Once this was done, the part was milled down to the correct size specifications. The mill was also used to drill holes in the piece required to attach the part to the rest of the arm assembly. After that, chamfers were cut into the edges using the mill and were then smoothed out further by filling them down by hand.

The plug was milled from the 1" diameter PVC rod. The mill was used to cut the rod to the correct length and also to cut the angled bottom of the part. This was done very carefully using an electronic protractor since the angle of the cut needed to be very precise in order for it to fit with the rest of the arm assembly. Once this was finished, four holes were drilled in the part using the mill. Two of them were blind holes and will hold screws that attach the scoop to the plug, and the other two will be used to secure the plug to the main arm section. The part was finished by tapping the two blind holes.

Below is a photo taken of the three parts near the end of manufacturing. The parts from left to right are the scoop, axle, and plug. The plug is still missing the two tapped, blind holes and the axle is also missing its two tapped holes. The scoop is missing holes as well as the chamfers on the corners. An up-to-date picture of the finished parts will be posted soon.

This next week we will finish our engineering and manufacture the last two parts of our MCM, the front plate and the main section of the arm.

First Manufacturing

Today, we manufactured our first part. Using the lathe, we turned the axle for the arm, our most critical module.

Sunday, November 15

This week, we primarily focused on finalizing the fundamentals of our machine. The axle for our scoop arm will be constrained by two pillow blocks as shown in the CAD image above. The torque from the motor will be transmitted to the arm axle by a combination of a worm gear and spur gear. We chose to use a worm gear for a couple reasons. First of all, the worm gear will greatly increase the torque output in our arm. Secondly, a worm gear cannot be back-driven, so opponents are not able to push our arm back once we have fixed it into a position. The worm gear and worm we plan to purchase are from www.sdp-si.com, and are similar to the ones shown in the photo below. The worm gear we will purchase is made of polymer because our machine does not require one as heavy-duty as steel.

We had planned to have our arm nearly manufactured by this week; unfortunately, the ME250 shop did not have openings, so our arm manufacturing is being pushed to next week. Our goals for next week are to complete the rest of the engineering for our chassis (which is the remainder of our machine) and to manufacture and assemble our arm module. If all goes as scheduled, we plan to have our solid assembled model and drawings for our entire machine completed by the weekend so we can begin manufacturing the remainder of our machine early next week.

This past week our group worked primarily on the MS6 assignment, redesigning our most critical module (our arm). We changed the materials of some of the components to PVC pipe (white components in picture below) in order to minimize the weight of the arm while still keeping it relatively strong; it is now about 1/5 as heavy as the original design (about 4lbs reduced to about 0.8lbs). This will allow us to rotate our arm faster, whereas before it probably would have been too heavy to rotate at all. Another benefit of our redesigned arm is that it does not have near as bulky a design with large unnecessary corners sticking out in crucial areas, such as at the bottom near the scoop. It will still take up almost the entire width of the slot with a flat face pushing the balls, however, to prevent balls from getting forced (wedged) into the walls of the slot and getting stuck, making it more difficult for our arm to continue rotating.
We decided to use the square aluminum rod for the axle by rounding the ends on a lathe in order to eliminate some issues with effectively constraining the axle to the arm section. It will be inserted into a square, interference fit hole in the top of the arm section. The PVC arm section will undoubtedly be our most difficult component of this module to manufacture with the square hole in the top and flat cutout with holes on the bottom half, not to mention the precisely angled cut on the bottom that the scoop piece with be assembled flush to. The scoop section will be attached by a PVC rod 'plug' which will then be attached to the front aluminum plate and PVC arm section. (see images below)

Please follow this link to see our week-by-week schedule for the rest of the term.
http://bit.ly/1YciNa

Description of Strategy and Concept

Our strategy is to move all of the balls at one time from our slot into the opponents slot. We will accomplish this using a car with a rotating arm attached to the car. The arm extends down into the slot and will be used to push and lift the balls over the wall onto the opponents side of the slot. The arm has a scoop on the end to help reach balls in the corner.

The concept will use a motor to advance the car forward and backward along the slot. It will also have guides in the slot so that the car will stay centered over the slot. The concept will use a winch attached at the top of the arm (above the axis) and below the vehicle to move the arm forward and backward.