Reflection John Doherty

This is the second time I am taking this class, but my first time in University of Michigan, and I can tell the entire experience is a whole lot different. From the lecture to the lab of what we learnt in class really helped me to understand, the process that goes into designing and manufacturing of the everyday things we use.

This class has taught me to understand the importance of teamwork in projects and also how to understand people while working in a team, combining people’s ideas to build a more effective and efficient device. The Machine shop section also built my confidence in using the machine because we had to make the entire vehicle from scratch, which I believe was a good idea. The Integration of the lecture materials and the hands on activates in the lab was amazing. It was good that we were able to get hands on feel on the things we were taught it class. I also understood the importance of drawings during manufacturing, and how planning to manufacture apiece before going to the lab helps saves time, and how sketching out your idea helps people to understand it better.

Some other things I learnt the hard way, it’s that you should always build a prototype of your machine because it helps to expose the hidden mistakes that we as a team might not have thought of. I also learnt that the importance of machine speeds and materials types during machining, it makes a huge difference when the final axle is made and because you lathed it at a higher speed that was required, the materials expanded due to heat generation and can no longer fit into the bearing or bushing. I also learnt that imagination is the key, adding features to simple mechanisms to increase its adaptability.

Also making using software like CAD might not be as accurate as we think, we should also take into consideration your machining skills, because tolerance is very importance and affects the final assembly. 

 I believe the course is great the only the thing is that the amount of work put between the milestone should be emphasized on a bit more and the exams times should be increased because, there was just so much information required for us in the exam and I discovered that the grading was done pretty fairly but, if it was explained to us before the exam that you don’t really have to go into deep explanations on your answers that would have saved me a lot of time to work on other things. I looked at a friends exam and for the Question requiring use to talk about the properties of machines I wrote a lot explaining my ideas and it summed up to be about a page and my friends who wrote a couple of sentences got the same points as I didn’t and for the Question about the design I wrote a couple of sentences and he wrote a whole lot and we still got the same credit, I think before the exam students should be aware of this because it helps save time. But that apart the integration of hands on materials with what is learnt is excellent and I encourage all design classes to adopt the Idea. 

Final Reflection - Ivan Manuel Gunawan

This ME 250 class has given me a very good learning experience. This is my first ever design and manufacturing class, and after finishing the course, I feel more confident about my choice of pursuing mechanical engineering major. 

The most useful thing I learn from this class is about the manufacturing process. Having my first hands on experience on the machine shop with the lathe, mill, and some other tools really fascinates me. It was not going easy for me at first. I made some mistakes at the beginning of the semester, and even got yelled once by Bob due to my carelessness. Nevertheless, I keep trying to get better, practice, and at the end of the semester I found myself become an expert on those machines.

From the problems that we faced during assembly process, I learn that precision and accuracy are very important and crucial in building a good machine. I also notice how the preliminary steps before manufacturing start, really play a big role. The CAD must have been reviewed carefully to minimize any error in the future.

Overall, the course has been set up nicely by both Prof Hart and Michael Umbriac. The idea of starting the whole project with a brainstorming in the group, and then giving each concept a pugh chart score, which leads to creating a mock digital model, really works well. I enjoy learning how to build a 3D model using the solidworks software. I wish we could have spent more time in learning some more features of this software, such as making animation of moving parts. I notice that this specific software is being used widely in the professional working field, and therefore it is worth the time to study the features deeper.

The essence of team work is also a good learning experience for me. I notice that later in the real world, we as engineers must be able to be cooperative with other engineers, to be able to complete a certain project. We have to note that not everyone is working at the same pace or style with us. We have to be able to receive critics and inputs from other teammates. Learn how to communicate the ideas in our head to other team members, and apply it to the final project. Those are some major components of team work.

On the other hand, I feel that the exam that was given to us was really tough for a first timer student taking design and manufacturing class. I found it tough just to remember all the new terms that I just heard for the first time in this class, and use it to answer the questions given. I think it would be a good idea for the instructors to review the proportion of time and amount of questions given in the exam. I also found it hard to know how deep the question expects us to elaborate the answers.

Homework are also sometimes very tough, because we only have two meetings every week, and I found it hard to apply the concepts discussed in five or ten minutes, to be able to answer the homework problems.

Final Machine

The final machine that we made varied quite significantly from the first CAD that we drew up with the largest change being the design of the upper arm on the pole. The changes have been documented in an earlier post on the blog.

The final machine had a was driven by two planetary gearbox with gear ratios of 100:1. The torque was then transmitted to the axles through a gear ratio of 1.5:1. The axles were supported at the sidewalls and a bearing holder made from the aluminum stock that we were given.

We had to make some changes to the base plate to accommodate the size of the gears. Changes included shifting the positions of the bearing holders and changing the placement of holes for the motor mounts. Also, we had to make holes in the base plate so that the gears had space to rotate.

Here are pictures of the (almost) final assembled machine. We later added a rubber pad to the side slope.

Final Reflection: Michael Frontera

      ME250 has, in many ways, been a great learning experience for me with respect to the design and manufacturing process. Perhaps the first thing that became very clear to me was the delicate balancing act that must be performed between choosing a design, and choosing a design that can be manufactured in a given time frame. For this reason, I think all else being equal it is very important to keep the design simple, while still meeting project specifications and requirements. Our design, for example, was a relatively simple one, with the drivetrain being the only actively powered component. Nonetheless, when it came time to move from the drawing board to the machine shop, many unforeseen problems and issues still arose which one might imagine would be even further compounded by a more complex design. A good example of the disconnect we experienced between our design and the final manufactured machine was with regard to gear alignment. While it is fairly easy to make everything line up well in a CAD model, translating that into the real world takes some machining ability. Now don’t get me wrong, Bob and Mark were extremely helpful at answering any questions that I might have had. Despite this, the limiting factor is always going to be the machinist who may or may not be able to get the part within the required tolerance. My takeaway from all of this would be to not fear taking risks in the design process, insofar as they are risks that would yield a benefit greater than the perceived risk while being able to be completed in the given timeframe. With regard to teamwork, I think it is essential to be open to the free interplay of ideas and to not rush to judgment with regard to ideas that may seem outlandish or unconventional. Of course, there are bound to be conflicts and disagreements in any team – that is simply human nature. The key is to handle them in a level-headed manner, letting rational discussion and not emotion win the day. Another lesson learned is the great importance of proactivity when undertaking a large project such as this one. If you don’t stay on top of the task at hand, things tend to compound very quickly and can leave you scrambling to make up for lost time. Overall, I think the course was organized fairly well and I appreciate all of the behind the scenes work that was put in by the professors and GSI’s to get the class off the ground. Several recommendations I would make would be to allow teams to start manufacturing earlier so as to spread out the student load in the shop and I found the ctools site a bit scattered and difficult to navigate as well.

Team Video

Reflections - Eugene Bong

ME250 was the first design class that I’ve taken in the University and it has been quite an interesting learning experience. The class introduced me to SolidWorks, the first CAD software that I have used, and I found it to be a very useful tool in the design process. I think that it’s a good idea to start with SolidWorks, which I have heard is one of the easier CAD softwares to learn. However, it would be even better to teach us how to use the other capabilities of the software, such as the simulation capabilities that I believe was mentioned in lecture. The material covered in lecture made me realize how many things we had to consider when designing a product. While going through the design and manufacturing stages, I realized that the process often involved trying something, and then going back to the drawing board to deal with unanticipated issues. The manufacturing process also taught me to understand the differences that could arise between the CAD and the final product due to our lack of machining skills. We also often had to deal with issues on the fly, and take setbacks in our stride. Teamwork was crucial in this project, and I am grateful that the members of the team pulled their weight, and complemented each other’s strengths. Conflicts were inevitable but we usually managed to resolve them quickly and move forward in the project. The class reminded me of how important it is to be open to ideas and opinions, and also how important it was to have a mediator in the group. It would have been disastrous if the group fell apart. Time management was one extremely important aspect that I feel we did not do too well in. When the project first started out, I underestimated the difficulty of the project and felt like we had plenty of time. As a result, it became a frantic rush towards the end of the project. Luckily for us, it all worked out, and the project ended on a fairly good note. Nonetheless, if repeated, I would probably want to start working on the project earlier, and spread out the work a little better over the semester. I thought that the course was a little disorganized at times, and instructions were sometimes unclear. This was especially apparent in the homeworks, where I often did not understand what they expected us to do. Also, because so much material was covered in during lecture, it was sometimes difficult to find what is needed for the homeworks. Another issue was the apparent disconnect between the machine shop and the GSIs when we first started machining. I understand that everybody is busy, and that they’re trying their utmost, however, it would still have been nice to have consistent instructions. Things worked out as time went on, however. Finally, I found the CTools page to be hard to navigate and it often took quite some time to find the document or information that I was looking for.

Final Bill of Materials

 Final Bill of Materials

Final Cost: $15.96

Pole Adaptive Design

Pole Adaptive Design

When we first design our machine to do the strategy of getting the red and black balls on top of the tower, we found out that the tower had some kind of flap extension which will cause problems when we are trying to get the black ball. The upper arm will hit the flap, which makes the machine not able to reach the black ball.

Therefore, we came up with an idea of using a spring steel and a magnet which enables the upper arm to deflect when it hits the flap, and then turn it back to the original condition.

We also intentionally made the lower arm tilted at an angle to make sure that the black ball falls to the designated slope area. It also turns out that making it at an angle will help the lower arm to reach the black ball easier.

This is the physical image of the arm after manufacturing process.

Working hard on the project!

Manufacturing / Assembling Problems

Manufacturing / Assembling Problems

1. Mouth

   The gap between the right and left mouth appears to be too wide.

   

   Solution:

   Bend the mouth inward.

   

   Before                                                                                After

              

2.Base Plate

    The holes made on the base plate were not accurate. This caused problems with a misalignment
    on the gears, and resisting the motion of the axle. 

                          

3. Center of Gravity

     After being fully assembled, the center of gravity was behind the axle causing the motor to fall

     backwards.

     Solution:  
     Install another ball casters on the back of the machine.

                                       

4. Slope

    The ball rolled off the side of the slope.

   Solution:

   Bend the side of the slope to provide a "fence" for the ball.

                                      

To do list

- Created a google doc containing a parts list and a to-do list for each part. Shared it with all of you so you    should be able to edit the document. Look at it and see if I missed out anything.

- Base plate holes are off, look at updated CAD uploaded on CTools.

Lots of things to do before the design expo! We need to keep working hard.

I DONT THINK THE BLOG IS FOR POSTING COMMENTS, WE SHOULD POST PICTURES OF OUR PROGRESS AND MODIFICATIONS IN OUR DESIGN.

I plan on manufacturing the base plate using the laser cutter on friday, so lets try to finalize our gear ratio for the planetary gearbox so i can get the correct hole placement for the motor mount.

To do before MS7

1) Change size of bolts in CAD to #6 screws
2) Finalize motor-gearbox combination (calculate expected speed of vehicle)
3) Finalize mechanism and design of pole arm
4) Figure out how to attach shaft on to wheels

Strategy and Machine Concept

Strategy and Machine Concept

Our main objective is to get one of the high value red ball at the tower perches and deposit it to our goal as fast as possible, to then continue with defense strategy preventing the opponent to score.

If opponent are trying to collect red or yellow balls to be deposited at their goal, then we will place our machine on top of their goal to prevent them scoring. Depending on the situation, we also considered "stopping by" the tower perches to collect one of the black ball (step 5) to play "the swap" tactics.

If opponent are trying to collect the black balls, then we will just stay at our goal to prevent them from depositing the balls at our end.

To reach this objective, we designed our machine to have three important features:
1. Extending arm to reach the tower perches
2. High speed and maneuverability by having independently driven wheels.
3. Wide base and two rollers to prevent the machine falling into the hole.

Below are the screenshot of our "Solidworks" machine design concept:

Team Schedule

Here's the team schedule, which includes the tasks we have to do, the due date and the person(s) responsible for each task.

http://goo.gl/Z4RKw