Pinball Machine

Step One: Teaching Phase: How will the teacher present the concept or skills to students?

1. Show students examples of pinball machines by showing the following videos: https://www.youtube.com/watch?v=gnrrbKFWL3Q https://www.youtube.com/watch?v=jqwOaPYjKXI (min 11:57-end)
2. After watching the video, discuss the motion of the flipper. The flipper transfers energy to the ball to keep the ball in motion. Discuss with students how pinball machines are controlled with electronics so the energy transfer is electrical to mechanical.
3. Show that the transfer of energy in their cardboard pinball machine will be elastic to mechanical.
4. Point out that the travel of the ball is interrupted by bouncing off obstacles. These obstacles make the play more interesting.
5. Show that there is a launcher mechanism off camera that causes the ball to launch into the playing field. The launcher gives the ball the initial speed on the playing field.
6. Discuss the rubric for the activity.

Step Two: Making the base (Time 30-60 minutes)

1. Cut a rectangle out of corrugated cardboard to the desired size.
   This is usually 18-24 inches long and 13-16 inches wide.
2. Cut some long strips of cardboard to make the 4 sides. These sides will keep the marble on the playing field.
3. Glue the strips around the perimeter of the board.
4. Add cardboard ramps, cardboard obstacles, or small toys around the board to create obstacles or rebound surfaces. Students can also make their pinball machine themed with vinyl decals if time, materials and equipment permit.
5. Cut angled cardboard pieces to attach to the bottom of the base to provide an angle for the playing field. A fast board has about 12-15 degree slope. A slower board has about 5 degrees slope.
6. The included design files have all of the necessary components for an 16 inch x 10 inch base with a 10 degree slope and is capable of being made on an Epilog Mini 24”x12” laser cutter common in many Fab Labs. The file may have to be modified to work with your local equipment.

Teacher Led Discussion: Gravitational potential energy depends on the height of an object above the ground. In the pinball machine a larger angle results in a larger gravitational potential energy therefore larger kinetic energy. Because KE = ½ mv2 higher kinetic energy translates to higher speed.

Step Three: Making the flippers (Approximately 30 minutes required)

Teacher Led Discussion: A bell crank mechanism transfers horizontal motion to vertical motion. Show student videos of bell crank mechanisms in motion.

• https://www.youtube.com/watch?v=-nuAhMMAbXw,
• https://www.youtube.com/watch?v=26D-_Fo0Tlk.

1. For the pinball machine, the short leg is attached to the push button from the side of the pinball machine. This is the horizontal motion. The long leg has vertical motion and bats the marble back onto the playing field. Essentially a bell crank mechanism is two levers attached at a stationary point.

   Basic Bell Crank 

2. Make a single L-shaped flipper from cardboard. This is a basic bell crank mechanism. A good starting point is for the long part of the L to be 3 inches and the short part 2 inches.
3. Drill a stationary pivot hole in the corner of the single layer flipper.
4. Test the flipper shape, size, and placement of the pivot and push button points. Your goal is to have a small horizontal motion, with a small forcerequired and a fast vertical motion to give the ball more speed.
5. Once you have decided on your design, build two final flippers by gluing 4 layers of cardboard together.
6. Cover the front of the flipper with poster board to give the marble a good surface for bouncing. The included design file has the components for two sets of flippers and is capable of being made on an Epilog Mini 24”x12” laser cutter common in many Fab Labs. The file may have to be modified to work with your local equipment.

Step Four: Make Push Buttons (Approximately 15 minutes required)

1. Cut small rectangles about three inches above the bottom edge of the box.
   
2. Cut and glue long strips of cardboard to make the main part of the push button. (See diagram below)
3. Make small squares off cardboard to glue on the end to make top of the push button. This will be the part that the player will use to activate the mechanism.
4. Place the push buttons in the rectangular slots on the playing field (created in #1)
   

Step Five: Attaching the button to the flipper (5 minutes required)

1. Attach push button to the flipper in the location determined in Activity 2. Use brads, bolts, or skewers that will allow the pushbutton and flipper to rotate. You will need to come up with a design to effectively attach the buttons to the flippers. The basic design is shown.
   
2. Add rubber bands to flippers and buttons provide a return force. Play with the arrangement of the rubber bands to find the best return force and smoothest flipper motion.Teacher Led Discussion: The arrangement of the rubber bands is very important. When the button is pressed the rubber bands should be stretched. The work done in moving the button transfers energy to the rubber bands. That energy is then released when the button is released and the rubber bands pull the flipper mechanism back to its original position. Some of the energy is transferred to the marble on the playing field.
3. Once you are satisfied with the arrangement of rubber bands, flipper, and buttons, permanently attach the flipper mechanism to the playing field with a bolt, skewer, or dowel through the stationary point.
4. Glue cardboard strips to the playing field to provide guides for the push button.
5. The included design files also incorporate push buttons.
6. Measure distance between where the button attaches to the flipper and stationary pivot:                  
7. Measure distance between where the marble hits the flipper and stationary pivot:                            
8. Find the IMA which is the ratio of the two distances (6 divided by 7):                               

Step Six: Making a launcher (5 Minutes required)

Teacher Led Discussion: The most common launcher for a pinball machine is a spring system, as seen in the picture to the right1. A spring system is very similar to a rubber band system because they both convert elastic potential energy to kinetic energy. A spring system can be stretched or compressed to gain elastic potential energy; however, a rubber band system can only be stretched. In the following directions, students will create a rubber band launcher. In the rubber band launcher pulling the paddle does work on the launcher mechanism creating elastic potential energy. When the system is triggered, the elastic potential energy is converted to kinetic energy putting the ball into motion. Students can develop alternate ball launching mechanisms such as a gravity ramp launcher or spinner launcher.

Picture from www.Pinballdecals.com

1. Fold out a file folder and roll it up to make a launching tube.
2. Glue a circular cardboard piece, slightly smaller than the launching tube, to the end of a dowel rod, paint stirrer, large craft stick, pencil, or similar long cylinder.
3. Place the plunger made in #2. Attach a rubber band from the top of the file folder tube to the plunger. To change the speed of marble launch, change the type of rubber band and placement of the rubber band on the plunger.
4. Attach the launcher to the side of the pinball board.
5. Cut a square hole in the side of the top of the cardboard base.
6. Attach a flat piece of cardboard and a curved piece of cardboard to carry the ball from the launcher to the playing field.

Step Seven: Making a ball catcher (5 Minutes required)

1. Cut a 3 inch long x 1 inch high slot in the bottom of the playing field for the ball catcher.
2. Create a catcher box by gluing together a small rectangular box.
3. Attach the box below the 3 inch slot.
4. As an extension activity, have the students design and laser cut their own box for a ball catcher.

Placing obstacles on the playing field/decorating the pinball machine

1. Choose objects to place on the playing field to make obstacles for the marble as it travels on the playing field.
2. Carefully decide on the layout; make sure that the marble will not get stuck on an obstacle.
3. Use hot glue to attach obstacles.
4. Paint or decorate the pinball machine to match a theme if you have chosen one.

Step Eight: FINAL PRESENTATION

1. Students present their pinball machines to the class.
2. Students complete reflective memo for the (uploaded to folder)

Teacher Led Discussion: Teacher will discuss levers and inclined planes, which are two of the simple machines. In most cases simple machines are used to make our lives easier by requiring a smaller input force to get a larger output force. In the case of the flipper, we sacrifice the force advantage to gain a larger range of motion.

The inclined plane is the playing field of the pinball machine. By having an angle we increase the speed of the marble as it goes down the incline toward the flipper. This makes the game more exciting and challenging.