2. Design Process - Pinball Machine

As stated in the introduction, we originally wanted to create a simple four-bar slider mechanism that would move the ball from the ball return back to the shooting point. Our main concerns for this mechanism were keeping the motion of the joints smooth, and finding a way to connect the slider to the ball holder, since the mechanism would be outside the box and the ball would remain on the inside. 

Our plan to build the actual machine was to laser cut the sides and the top of the box. We decided to attach the slider to the inside of the box and either laser cut or 3D print a holder for the ball to sit in while the slider moves it across. Our initial design is below:

From this, we changed a few things, but ultimately created out first prototype with a crank slider mechanism using this cad:

After creating our first prototype, we realized that we wanted something a little more complicated in order to get a good grasp of what we had learned in the class. For our next design, we settled on a quick return mechanism. We decided to use this because it still made use of a slider and the mechanism was similar enough to a four bar that we did not need to change the dimensions of the actual box as much. The reference we used is below:

What we did need to take into account was tolerancing. Since we were planning on using bearings, the holes on the linkages needed to be exact enough to create a snug fit. The slot we were planning on having the mechanism move through also needed to be tight enough for the bearing to fit without slipping out but also loose enough for the slider to move smoothly. 

The other issue we ran into was connecting the slider to the “outside” portion of the mechanism. The slider we had was metal, and we had by then decided on 3D printing the holder parts. We settled on trying to 3D print a side piece to be glued onto the slider that would contain a pin which fit into the bearing.

For the movable tabs, we planned on using rubber band tension which would allow the player to move them up by pulling a stick outwards. For the ball shooter we decided to try using a spring loaded 3D printed shooter, and we were planning on 3D printing and laser cutting the obstacles for the top of the box.