Maze Game Toy

Narrative:
You are on a design team responsible for producing a double sided maze game toy made up of three separate parts. The parts needed are a frame with several machined steps, a game board with two holes and a path machined into both sides, and a clear plastic cover for both sides of the game box. Care must be taken in the sizing of parts to insure all the parts fit together. The permanent fastening of parts can be done with a drop of super glue in the middle of each step that secures the game board and clear covers.

Instructors should note the complexity of this activity may require splitting up the part design and production process among at least two classes. This will present a great opportunity for collaborative interaction between engineering design teams on a number of issues such as: sizes of parts, cooperative research, precision measurement to insure interchangeable parts, tolerances, fixturing of double sided work pieces and finally the assembly of the Maze Game toy.

Because of the number of pieces to be machined on one CNC mill, fixturing of work pieces may require simultaneous vise setups on each end of the milling machine table. The machine zero settings on the milling machine can be adjusted in the mill control software to accomplish this.
A solid model of each finished part will be produced with Autodesk Inventor or Mechanical Desktop. The CNC code will be produced using SurfCam and the part machining will be completed using a 3-axis milling machine and a parts handling robot.

The use of individual part design teams of 2-3 students should be formed. A team leader is to be determined by the team members. The team leader must have prior experience with Mechanical Desktop or Autodesk Inventor. This requires a team leader who can elicit cooperative and productive work from all team members, in order to meet production deadlines.

Each team will design a Maze Game part according to instructor pre-determined specifications and present their designs to the class with a PowerPoint presentation. The class must then select one design for that classes production contribution to the Maze Game Toy assembly.

Concepts:
Teamwork; brainstorming, sketching; extrude; fillet; sketch plane; sweep with cut option; mass properties of volume and surface area; CAM-CNC details: selecting proper tools from tool library, speeds and feeds, tool path generation, tool path simulation; verifying cutting cycle time, including rough and finish cycles, creating CNC code, editing code as needed, modifying vise to properly fixture .125” thick plate stock; modifying vise to properly fixture stock for double sided machining, robotic parts handling set-up and programming; parts production; PowerPoint presentations

Geometric Requirements:
The raw stock for the game frame box is 1.000” x 2.000” x 3.000” Butter Board machineable plastic or a selected hardwood. Prototyping this part could be done with machineable wax. This size stock can be easily fixtured in the existing vise.

The game board is made of .125” x 2.000” x 3.000” aluminum plate stock. The plastic covers are made from .125” x 2.000” x 3.000” Plexiglas. It is recommended that an extra set of vise jaws with .125” wide slots be fabricated to properly fixture plate stock.

The Maze Game parts that are made from .125 plate stock, require at least a .1875” safety margin between the finished part boundary and the edge of the raw stock. This width of safety margin will work fine for .125” end milling cutters. If you use larger diameter cutters, the margin must be increased accordingly. The instructor must carefully monitor the safety margin. This will prevent damage to the vise jaws during the machining process. Students need to be reminded that the cutter bit has a width and must be accounted for in the safety margin.

The plastic cover for the top and bottom, must have two small breaks on opposite sides of the part. This will produce a narrow support web so that the finished part remains stable in the raw stock. This is necessary to prevent the finish part from dropping into the bottom of the vise upon completion of the machining cycle. Remember, one of our goals is to have the robot load and unload the workpiece. If you are using a .125: end mill, the break in the part boundary should be .1875”.

The part boundary for the game board must not be cut until both sides of the part have had the game trail paths machined. Again, as in the plastic cover design above, the part boundary must have two small breaks on opposite sides of the part. This will produce a narrow support web so that the finished part remains stable in the raw stock. This is necessary to prevent the finish part from dropping into the bottom of the vise upon completion of the machining cycle. This will enable the robot to load and unload the work piece.

Inquiry:
The following tasks are to be competed with the aid of the mass properties function and the appropriate calculations. Each team’s results will be presented to the class using PowerPoint as part of the design presentation/selection activity. All parts must have a three view dimensioned orthographic with isometric view. The drawings are to be printed on 11” x 17” paper.

A. The part design documentation must include the finished product as a solid model prepared with Mechanical Desktop or Autodesk Inventor. A properly dimensioned orthographic drawing with an isometric view must be completed and printed on 11” x 17” paper.

B. All part cost calculations are to be based on a production run of 1,000 pieces. (For the actual production within the classroom, the production run will be limited to a class set plus two extras for the instructor.) Calculate the cost of raw stock necessary to produce 1,000 pieces of your team’s part. After the final design for production has been set, the design teams must collaborate to predict what the total material cost for all parts will be.

C. Using the CAM software, predict what the total machining cycle time will be to produce 1,000 pieces of your team’s part. After the final design for production has been set, the design teams must collaborate to predict what the total machine cycle time will be for all parts.

D. After determining the finished product’s volume and weight, predict what the shipping charges will be for 1,000 Maze Game Toys if they are shipped from our school to Oswego, New York 13126.

Other Applications:
What other products would make use of the design and manufacturing techniques applied to the Maze Game activity?

Evaluation:
How closely does the product design adhere to the geometric requirements?
Team leader’s and teacher’s evaluation of each team member’s contribution
Teacher’s evaluation of how well each team collaborated during the design and production phases.
Peer ratings of PowerPoint presentation – rate each on a scale of 10
Creativity of product design
Creativity of PowerPoint presentation
Quality of graphics and text in PowerPoint presentation
Organization of PowerPoint presentation
Quality of the product documentation drawings
Creativity and effectiveness of the PowerPoint advertisement
How well did the presenter demonstrate knowledge of the topic during the presentation and the question/answer session?
Did the presenter speak loudly enough to be clearly heard?
How well did the presentation hold you interest?
Did the presentation convince you that this design should be produced?
The instructor can also use the oral presentation rubric found on the PLTW resource CD.

Supplemental Information:
Aluminum costs $3.50 / lb.
Density of aluminum is .0974 pounds per cubic inch
The feed rate for part boundary separation should be 1 – 2 inches per minute, with spray coolant/lubricant applied as needed to extend toolbit life.
∑ The feed rate for game trail paths should be 3 – 4 inches per minute with lubricant applied.