Today I began this project by working up a prototype of the drum that will hold the sliding cams that trigger the micro switches. Designed in SketchUp and printed on a Hictop 3DP11 printer.
The final drum will be about 100 mm in length and 100 mm in diameter. The cams will be made in three different lengths to correspond to a quarter note, half note and whole note. The part that slides back and forth in the drum will be the same dimension, only the length of the cams will change .
Pictured here is a proto cam that represents a quarter note. This was printed with ABS in draft mode with a 20% fill, print speed 100, bed temperature 80C, extruder temperature 240C.