2.810 Manufacturing Processes and Systems

Project Instructions

The group project will consist of the fabrication of one radio-controlled car per student. Each team of N students must create one design for all of its cars, and fabricate N car bodies with one swappable control box that is transferred from one car to another during the race. Each group is given an initial set of materials and a small budget to purchase extra materials if needed. Further details about the project are described below.

SolidWorks

Designs for all fabricated parts should be drawn in SolidWorks and included in the final project report. Please bring print outs of dimensioned drawings to the machine shop whenever you are fabricating a part. Additionally, drawings must be exported in DXF format for use with the OMAX software on the waterjet.

SolidWorks is provided for free to MIT students and can be downloaded from MIT IS&T.

Note: (a) SolidWorks 2015 runs only on 64-bit Microsoft Windows systems. (b) SolidWorks 2015 is generally not backwards compatible with previous releases (2014, 2013, etc), so if you plan to share SolidWorks files among team members, it is advisable for everyone to use the same version. (c) If you do not have a computer that supports SolidWorks, the LMP machine shop has several computers with the software.

Provided Parts

Below are SolidWorks drawings of the parts given to each team. Feel free to download and use these for your designs and the final assembly drawings and edit them as needed. Before using these drawings, make sure all dimensions are correct/actually correspond to the items you have on hand. Note that these drawings were made in SolidWorks 2014; they should be importable into SolidWorks 2015 but it has not been tested, so let us know if you have any issues.

• Battery
• Bearing, front
• Bearing, rear
• Collar, front
• Collar, rear
• Eclip
• Motor
• Pinion Gear
• Receiver
• Screw, front
• Servo
• Shaft, front
• Shaft, rear
• Speed Controller
• Spur Gear
• Steering Block
• Tires, rear
• Transponder
• Washer, front
• Washer, rear
• Wheels: Front, Rear

Group Organization

An important aspect of this project is that you organize yourselves into groups (usually 5-8 people) and carry out the projects in a cooperative and productive manner. Your responsibilities are to develop your car design, competitive strategy, and manufacturing tasks as a group. Your first assignment is to find a mutually agreeable time period per week to work on this project. We are interested in knowing how well your group functions, how the work load is distributed, and how you dealt with problems and conflicts. You will periodically be asked to self-grade your group's performance. (Past experience has shown a very strong correlation between well functioning groups and a successful physical product.) The group should record important decisions and problems for the group progress reports. You will need to record your organizational structure and the division of tasks for your progress update and final report.

Physical Product

The most important aspect of this project is that your group successfully complete the assembled cars using the various manufacturing processes. You will be required to build N (identical) cars for a group of N people. Each car must be prominently labeled with the letter designation of the team and the car number (e.g., A1, A2). The car should demonstrate good design and manufacturing technique, with the aim of showing a satisfactory performance in the final race contest. After the contest, one car per team will be left with the instructors for grading (the car will be returned after grading).

Written Report

A short report is required to accompany your car on the day of the contest. The text of this report should be written in the spirit of an executive summary. It should acknowledge the sources of the ideas your group used. The report should include:

• A photo of your car
• A list and photo of group members
• Design drawings for all fabricated parts and an exploded view showing the assembly of the car
• Tasks performed by each group member
• Very brief discussion of the key design and manufacturing features for your car

Please use 12 point font, 1" margins and 1.5 line spacing. Do not exceed 6 pages of text (not counting photos, drawings, tables, etc). No appendices are allowed.

Grading

Overall the project will count for 30% of your grade. There is an additional 10% participation component that factors in group contribution and teamwork as well as class/lab attendance and participation. The same project grade will be assigned to the entire team. Therefore, it is the group's responsibility that each member contributes equally. The grade will depend primarily upon the physical cars and the effort demonstrated in producing it. Quality of manufactured parts, fit and finish and performance of the assembly and disassembly scheme as judged by the instructors will all be considered in the grading. Performance in the contest on the final day of class will also be considered. Note that the other 60% of the final grade is split between Quiz 1 (30%) and Quiz 2 (30%).

Design Rules

Each group will receive a toolbox with a set of tools and items needed for car assembly. Additional car parts will need to be fabricated and assembled using tools and materials available in the LMP machine shop.

1. LIST OF RAW MATERIALS
2. General rules:
   • Cars are limited in size to 11” x 12” x 11”.
   • Each team car must be identical.
   • Each team is allowed $20 per car to purchase items, which must be purchased through Bill Buckley. You cannot use your own money to purchase items.
   • Cars must contain at least one each of the following processes: thermoforming, sheet metal forming, machining.
   • All questions or requests for clarification of any of the rules must be made to Bill Buckley or Professor Gutowski.
3. Chassis:
   • The chassis will be cut from an aluminum sheet (maximum thickness: 0.25") on an abrasive waterjet machine.
4. Wheels:
   • Wheels will be manufactured by injection molding. Tires will be made by overmolding.
   • Diagrams for front and rear wheel assemblies.
   • You may only use the supplied gears. (Should you want to use 2 sets of gears this will use your $20 per car budget.)
   • Tires can only be manufactured with the supplied neoprene material.
   • Maximum tire diameter: 4” (maximum waterjet cut time: 45 sec per tire).
5. Shell:
   • Cars shall be covered with a continuous Thermoformed shell. No cartridge penetrations in the shell. Control units may be changed from underneath or by removing the shell.
6. Electronics and control box:
   • You must use the supplied electronics and motor; no substitutions or modifications are allowed.
   • DO NOT cut any wires on the RC electronics.
   • Only use the screw supplied with the servo attachments; using any other screw will damage the servo.
   • The battery, motor controller, transponder, receiver and servo must be located in the control box.
   • The control box will be reviewed for design for manufacturing.
   • Each group must design their cars for assembly and disassembly of the radio control unit during the race.
   • All assembly must be made by mechanical fastening only. Duct tape, Velcro or similar products are generally not allowed.
   • Radio controller manual
   • Battery charger manual
   • 
     Each team will receive one transponder, which will record lap times, and must be switched between laps from car to car, along with the radio control unit. The transponder must be mounted horizontally no higher than 15 cm or 6 in (lower is better) from the track. It is recommended that no metal or carbon fiber is between transponder and track, and that the transponder is not directly mounted to the metal chassis. For more information, please see the manufacturer’s website or download an installation manual.
7. 3D Printing:
   • No 3d printed hardware is permitted on cars used in the competition.