Prototype 2 - Slayer wannabes
Summary:
The second prototype featured a significant milestone: simplified cam actuation and cam contour redesign. Our group decided that there was simply no use for the paddles and cables if each cam simply actuated a lever to fret the strings. The second prototype was built with a fully functioning fret actuation system and working percussion shaft. The cams were redesigned to take up half of the circumference, which means less distance for the motor to traverse for each note. This increases the torque capacity on the motor, but will increase the maximum speed at which the song can be played. The activated portion of the cam contour was also slimmed down, meaning there is now negative space for each cam, making all cams identical. Each cam now has a generic shape that allows only one note to be pressed at a time. This greatly reduces the load on the motor and allows for a more generic single cam design as opposed to custom cam designs for each note.
This changes the fretboard and associated camshaft by simplifying the construction dramatically. Another added benefit is the dramatic drop in friction between the cam and the actuation lever.
This shows the evolution of the cam designs over time. The whole cam was taken up for note timing, which was inefficient for our mechanism. The design was then cut down to use only half of the cam circumference, which means less motor travel distance. However, the best design was single-note actuation that only takes up half the circumference.
The cams were rounded, leading to a smoother on/off period for hitting each note.