Final Team Documentation

Our machine has a few key components to it. The chassis is the backbone of the machine and is composed of different materials. The sides of the chassis are made of 1/4” aluminum and can be seen in Figure 1. The front is made of 1/16” aluminum with a bend in the end so no balls get caught on the front of the machine and can be seen in Figure 2. The top is made of acrylic and the bottom is made of delrin and these can be seen in Figure 3. Each piece of the chassis has multiple holes drilled in them so that brackets could be mounted as well as other devices such as our prodder arm and our most critical module, the bulldozer blade. 

 

                        Figure 1: Side Chassis Plates                          Figure 2: Front Plate 

 Figure 3: Top and Bottom Plates

The bulldozer blade is made of two acrylic arms with a delrin blade, seen in Figure 4. The rotating shaft of the blade is connected to the machines by two pillow blocks, which are screwed into the sides of the chassis. Each arm has a screw going down the beginning of the arm as well as the shaft, allowing the arm to rotate and not just slip in place. The gear on the shaft is connected to a gear from the planetary box using a custom fashioned silencer. The gear ratio of the planetary box is set at 80:1, allowing it to have enough torque to lift. Figure 5 shows a pillow block as well as the rotating shaft through the acrylic arms.

Figure 4: Bulldozer Blade

 

Figure 5: Side Pillow Block

A metal motor drove each of our wheels. We found that this motor combination allows for ideal torques and speeds. The metal motors are very strong and don’t lose much power through gear deficiencies due to the fact that they don’t have gearboxes. These metal motors can be seen in their proper places in the chassis in Figure 6. For each motor we connected a axel by using another silencer and two set screws. One setscrew attached the motor to the silencer and another screw attached the silencer to the axel. The axel was then press fit through a bearing and into our wheel. We then used epoxy to attach the wheel to the axel. The front of our car has two caster wheels to allow easy motion when turning. These were attached using epoxy as well. Lastly, we painted the chassis of our machine black to give it an aesthetic appeal. Figure 7 shows our machine mostly assembled right after it was painted and Figure 8 shows our complete machine.

 Figure 6: Insides of the Chassis

 Figure 7: New Paint Job

 Figure 8: Complete Machine

Steven Shannir's ME250 Review

    After I walked out of our first class session of the semester, I was left with so many questions. I had never designed a machine before. I had never operated large machinery, fabricated parts or even used computers to help design the parts. It is safe to say my experience for the whole process was well, zero. But for some reason I felt that the project assigned to us was so juvenile and easy. My ego made me believe that this project was not something for a Michigan engineer or a junior in a highly respected university. Of course though, I was wrong.
    My attitude to the whole project in the beginning was pretty off. I was not interested in working with a team because I wanted to implement my ideas and strategies alone. I was not interested in going about the machine or the strategy in any other way but mine. I also did not believe the work load was for a group of four either. This of course was before we made teams. It was not until after teams where made that I started to come around.
     During the actual lab sessions, groups where created and things started to roll pretty quickly. Ideas where constantly being bounced around and strategies formulated. Every individual had constructive criticism that really benefitted the project. I slowly started to come to terms with the idea of the team. Also as we continued to go lecture, the whole design process was explained and broken down to us in steps. This made the whole process a little bit more easier to follow and allowed for us to move forward smoothly.
    When the announcement for the project was made I believed it to be to easy. I quickly realized how wrong I was. I began to feel slightly overwhelmed about the project at hand. There was still so many questions and things to do. Designing the project on the computer was alien to me. Deciding what materials to make the machine out of was just as difficult. What really helped was the lab tutorials that was given on SolidWorks. These tutorials were literally my first exposure to engineering software and it did a great job on introducing its capabilities. I was even impressed that we were shown a resource to educate us on materials. This is where the labs really took care of my concerns while we worked on our project and was undoubtably crucial to our design.
    As the project started to develop and move further along, more and more issues seem to arise. The design process as a whole exposed to me how easy it is to overlook certain things. One of the major issues my team faced was how to assemble the machine together. We never really took the time to make in SolidWorks the locations of the screw holes or label how each piece attaches to one another. If I could go back to the beginning this would definitely be one of the things I would have liked to have change. In my opinion, If you could emphasize this issue way more during the designing portion of the class. If you could require students to include in their SolidWork’s model how each part connects to each other. It would save headaches for teams further down the road.
    As an introduction to design and fabrication, I feel ME250 did a great job. The introductory project was not to simple and not to difficult to handle. It exposes students to all areas of the design and manufacturing processes. Even though this semester was  a mixture of emotions for teams, I am defiantly happy that I took this course. The experience I gained from It gave me the hands on skills I need and the teamwork mentality to further my development as a Michigan Engineer.

Kyle's Reflection

Now that ME250 is over and I have had time to reflect on the course, I have come to realize many things. Firstly, and in my opinion most importantly, I now am sure that I have chosen the right path for my education by majoring in Mechanical Engineering. Although ME250 was hectic and frustrating at times, I now know I thoroughly enjoy the design and manufacturing process. On more of a fundamental level, I have learned a great deal this semester. I now have a strong understanding of basic terminology such as the difference between a tapered bearing and a deep grove bearing, and more importantly which one is more applicable to a certain design application. Understanding different methods of machining parts is a very valuable skill that I have taken away from this class as well.  For instance I learned what circumstances it is preferable to use a mill instead of a hand drill or drill press to drill a hole in a piece. It is also important to note that each machine has their limitations. For instance some rods are simply too small to cut down on the lathe. These limitations should be taken into account during the design process. This semester has definitely taught me about the importance of a complete and thorough design. The design is the backbone of manufacturing and without a complete design (nuts and bolts included) the project will not proceed smoothly.  

ME250 is a very involved class and can at times the project can appear daunting, however it definitely helps to be working with a team. During the design process it was interesting to see the differing approaches to most everything we did. Ranging from the strategy selection to the sketch model down to the actual manufacturing of the parts, each teammate had their own way to go about things. This was not a bad thing however. It was a good way to lay out our options, analyze the pros and cons of each option and come to a collective decision on which direction to go. This is a valuable experience because it is how the real world works. Some might say that working with a team affects an individual’s grade too much. I disagree because not only were there plenty of individual assignments, but being able to adapt to others and work in a team environment is a very important skill to have in the real world.

Time management is a recurring theme in ME250.  Milestones helped to keep students on track. However a part of the course that I found frustrating however was the how much had to be done between MS8 and MS9 in a small amount of time. Admittedly, it is each student’s responsibility to properly schedule out his or her project, however the schedule is a bit deceiving. At a glance it appears there is a week between needing to have the critical module complete and needing to have 90% of the machine complete, however with Thanksgiving break taking up four days of this week, there was only three days to accomplish this. I feel more of a forewarning of this could help future students. One other area I felt could be improved was the use of controllers in the final days. I think a sign up sheet for times with the controllers on a Google doc could be a very useful tool for future students.

My team could have improved our performance in two major ways. One is time management. We left slightly too much to be completed within the final days which created some chaos. We also should have had more of a simplistic design with a complete and perfect Solid Works model earlier in the class. Overall I feel that we worked well together and I enjoyed the class thoroughly.

Final Bill of Materials

#	Description	Use	Dimensions	Supplier	Part #	Other Details
1	Aluminum 1/16th thick	Blade	12”x18”	Kit
2	1/4th Acrylic Plate	Blade Arms, machine top	12”x18”	Kit
3	Flanged SS bearing	Drive axle shafts	¼’’ ID, ½’’ OD	Kit
4	3/8’’ Round Stock	MCM axle shaft	18’’ long	Kit
5	¼’’ Round Stock	Planetary gearbox drive axle	8’’ long	Machine Shop		Stock from the machine shop
6	1/8’’ Delrin plate	MCM blade, machine bottom	12’’x12’’	Kit
7	Aluminum Plate, ¼’’ thick	Chassis sides	6’x18’’	Kit
8	Aluminum tube stock	MCM axle pillow blocks	¾’’x ¾’’ x 1/8’’ wall	Kit
9	Flanged brass bushings	MCM axle	¼’’ ID, 3/8’’ OD	Kit
10	E-Clip retaining ring, ¼’’ Dia.	Constrain MCM axle	¼’’ Diameter	Kit
11	Spur Gear	Planetary gearbox transmission	¼’’ bore x 1.083’’ OD	Kit	A 1M 2-Y24024
12	Ball casters	Front guide wheels	13/16’’ tall by 15/16’’ wide	McMaster	6460K21
13	Pololu 1576 99:1 Metal Gearmotor	Drive Motors	25D X 54L	Crib
14	Tamiya 72001 Planetary Gearbox Kit	MCM drive motor	N/A	Kit
15	5 #4-40 Set Screws	Constrain MCM gears to planetary output shaft; constrain axles to drive motor shafts	#4-40	Carpenter Brothers Hardware	N/A
16	JB Weld	Constrain wheels to drive axle; constrain front bumpers to machine sides	N/A	Carpenter Brothers Hardware	N/A
17	L-Brackets (3 packs of 4)	Attach machine sides together	1.5’’ X 1.5’’ X 5/8’’	Carpenter Brothers hardware	N/A
18	1/4-20 bolts and nuts	Attach machine sides together	¼-20	ME250 Shop
19	Dowel Pin	Constrain MCM “silencer” to planetary output shaft	Approx. .077’’ diameter	ME250 Shop
20	#6-32 screws	Constrain the MCM arms to the MCM axle shaft	#5-40	Cage	N/A
21	Velcro	Constrain rear of the machine to our sides and allow for quick service	1.2 pull-apart, 200 cycles, 1’’ wide .188’’ thick	Kit
22	Wheels	Drive the machine	3’’ Diameter	Ebay
23	¼’’ steel round stock	Machine axles	¼’’ diameter	Kit

Purchased Items:

PURCHASE LIST
Item	Company	Total Price
Team Associated 21065 18MT Mounted Wheel/Tire/Insert	Amazon.com	$14.89
JB Weld & V115 IRON, CORNR 11/2X5/8	Carpenter Bros. Hardware	$11.21
Nuts/Bolts/Nails/Screws	Carpenter Bros. Hardware	$2.27
4 Pack Corner Brace Satin Brass	Home Depot	$6.32
Gimp/Basswood	Michaels	$5.06
Vinyl	Jo-Ann Fabrics	$0.70
Caster Wheels	McMaster Carr	$17.78
	TOTAL:	$58.23