Class Projects 
ME 643 - Elements of Design - what can I do with this bag of junk?
The Rules: The object is to build a car that will travel a distance of 20 feet in the shortest time. The vehicle must travel within two lines that are 18" apart. The vehicle must:
- fit into a box 12" x 12" x 12"
- be driven only by energy supplied by one or more onboard batteries
- be stationary with the power switch open at the time of start
- a total of 2 minutes is allowed to test the device
- the barrier at the end will be padded to prevent injury to the device
- more than one 9V battery can be used, however, if the motor burns up, zero credit is given
The Team: In traditional product development, a sequential process is employed: design, analysis, and production. In concurrent product development these functions are done simultaneously. "Tiger Teams" are often organized to attack projects that must be done on a tight schedule by bringing together experts from several different areas. Members of the team participate in almost all aspects of the project, but each one brings their own particular perspective to the project.
"Tiger Teams" will consist of four people to cover the following responsibilities:
Management – responsible for setting the schedule, organizing meetings, equalizing the workload, interfacing with the Professor, organizing the report, testing prototypes, resolving disagreements.
Design – responsible for design architecture, CAD drawings, sections of the report which describe design.
Manufacturing – responsible for the "bag of junk," signing out and returning the tool kit, fabrication of prototypes and final design. Safety is a concern. Will also act as the unofficial OSHA representative.
Analysis – responsible for applying proper engineering analysis to guide the design and assure proper factors of saftey, will write portions of the report which describes the analysis. Some questions that will need to be answered by the analysis: size of wheel, best reduction ratio, coefficient of friction between the wheel and floor, strength of elements that must resist motor torque. Most of the analysis should be possible with the information learned in Mechanics II – ME 526.
The Bag of Junk: The only materials that may be used to build this race car are from a “bag of junk.” The manufacturing engineer is responsible for picking up and storing the equipment. The items in the bag of junk are listed below in two categories: capital equipment and consumables. The capital equipment must be returned in tact. The consumables may be bent, sawed, and drilled in any way the students wish and need not be returned. Students should return any unused portions. If students lose or break any item, they must be replaced at the students' expense - see list below:
Capital Equipment (must be returned):
- Pitman DC servo motor with 127:1 reduction gearhead, weighs 470 grams - M.E. Dept. - $150.00
- Fuse holder (must use) - Radio Shack - 2700739 - $1.19
- Electrical switch (must use) - M.E. Dept. - $5.00
- Package of 9V snap connectors (must use) - Radio Shack - 2700324 - $1.99
- Small hose clamp (2) - Home Depot - $0.39
- Large hose clamp (2) - Home Depot - $0.69
- Ball Bearings (4) - M.E. Dept. - $5.00
Consumables (unused items must be returned):
- Venetian blind - Home Depot - $2.95
- ¼” x 12” x 18” plexiglass — Home Depot—$13.20 for 18’x24’ (yields 2)
- ½” x 12” x 12” plywood — Home Depot — $3.98 for 2’x2’ (yields 4)
- ¼” coarse thread rod - 18” long — Home Depot — $1.07 for 36” (yields 2)
- ¼” aluminum rod - 18” long — Home Depot — $2.11 for 36” (yields 2)
- ¼” nuts (10)—Home Depot — $0.03 each
- ¼” lock washers (10)—Home Depot — $0.03 each
- Wooden clothespins (10)—Home Depot — $1.88 for 50 (yields 5)
- 5 minutes epoxy—Houghton’s—$3.00
- Silicon rubber sealer—Radio Shack — $2.99
- Flexible tubing - ¼” I.D. x 3/8” O.D. (12”)—Home Depot—$.12/ft
- ¾” electrical tape (12” roll) — Radio Shack—$2.49 for 5pk (yields 5)
- Velcro fasteners — Radio Shack — $2.99
- 6’ of electrical wire — Radio Shack — $4.49 for 75’ (yields 12)
- Heat Shrink tubing - various sizes — Radio Shack—$1.99
- 10A fuse (must use) — Radio Shack — $1.39
- 9V battery — Home Depot — $4.97 (yields 2)
- Foam core (15” x 20” x 3/16”) — Staples — $8.45 for 30” x 40” (yields 4)
Wheels, an essential ingredient for most cars, have been purposely omitted from the kits. Students are required to fabricate their own wheels (probably from the plexiglass or plywood). Bear in mind how the wheels will be connected to the shaft?
Tool Kits: The project is designed so that students are able to build a car with fairly simple tools. A limited number of tool kits (5) are available for 24 hour sign out period from the M.E. Shop. The tool kits contain the following items: 1. electric drill, 2. electric saber saw, 3. soldering iron, 4. files (2), 5. safety glasses, 6. drill bits, 7. blades for the saber saw, 8. solder, 9. bandaids. Some useful items that are not in the kit, which students may wish to borrow include: a hammer, screwdrivers, pliers, dial calipers, sandpaper, paint, compass, and precision steel ruler.
The Report: A report is required describing the design. The report will contain the following sections:
- Title page – title, group members, group number, submitted to, date.
- Cover letter
- Introduction – purpose and topic of the report, a summary of the design should include weight, size and and performance results measured on the day of the test. A picture of the design would also be nice.
- Design Description – the design solution should be described in words and pictures. This section is the primary responsibility of the design member of the team. Isometric pictorials and exploded assemblies help describe the design. Dimensioned drawings should go in Appendix A.
- Design Analysis – what type of analysis was employed? How was the analysis used in the design? This should be a synopsis of the analysis, not the actual analysis itself. Detailed analysis, including MathCad sheets should be in Appendix B. This is the responsibility of the team analyst.
- Manufacturing – Describe the procedure that was followed to make prototypes and the final model. Provide a bill of materials (BOM) and process plan for fabricating the design. It should have enough detail so that a person unfamiliar with the design could actually make the product
- Problems encountered – summarize the biggest challenges and lessons learned. What would make it bette next time?
- Overall assessment – summarize how well the team did. Students should reflect on the strong and weak points of the design relative to the devices by other student teams.
- Appendices – detail drawings, analysis, other.
Appendix A:
General principles for report writing:
- Proofread, proofread, proofread!
- Strive for brevity - spend your dollars!
- Make it look good - page numbers, well organized, prooper use of fonts, enough white space.
Grading:
- 30% - Performance - how well did the design perform? This will be based solely on the elapsed time as compared to that of other teams.
- 10% - Aesthetics - a good product should perform well and look good.
- 25% - Analysis - good engineering is based on analysis and proper application of scientific principles.
- 35% - Report - the best ideas are worthless unless you can communicate them to others.
Group Self-Evaluation: All students in the group will receive the same grade, but some students will also perform self-evaluation, the results of which may be used to adjust final course grades.