3 - Model Construction

For the most part, I followed the directions listed in the Karakuri book. I only made a few modifications for measurements and in places where I felt might need additional reinforcement. I did not want the cam, flat-faced follower, or camshaft handle to be flimsy. For hobby use and personal entertainment, the thicker paper provided by the book is most likely sufficient. However, I knew my eventual measurements on the model would depend on these components. The equations and vector loops used in the textbook, which will be discussed in detail later in the Model Analysis section, seem to assume that the flat-faced follower and cam are rigid. For example, the displacement vector is perpendicular to the point of contact vector. If the cam or follower bent in use, the displacement vector would no longer be perpendicular to the point of contact vector. The sturdiness of the camshaft handle was also important to me since I would be depending on it to make angle measurements. For these reasons, I decided to trace the shapes and cut each component out of cardboard. The cam and follower in my model are not perfectly rigid of course, but there is still little to no bending.

I also added an angle chart to each side of the camshaft to help me measure the camshaft’s angle of rotation. I cut out windows from the model base so I would be able to see inside. Not only did this help me to better understand the motion of the model, but also, this allowed me to measure the approximate location of the point of contact between the follower and cam. A window was also cut from the back of the penguin. In order to come up with a function for the fin’s position, I needed to know the fin’s total length and where the fin hinged. With the model constructed, I could now move on to plotting motion profiles.

          Figure 4. Degree chart on camshaft handle side.                    Figure 5. Degree chart on opposite side.

             Figure 6. Windows in model base.                     Figure 7. Window in penguin’s back.