Track number limitation

We were able to accomplish the task of each individual track mechanically, but not able to have all five tracks like originally planned.  Inside each cartridge were photo gates, which limited how small we could make the striker (see Figure 2).  The photo gates were important in detecting the position of our striker.  We created a "tooth" tracking system), which was attached to the rails as shown in Figure 1, and would run inside the photo gates so that the photo gates could detect it.   Because we were unable to make the striker cartridges any thinner than the width of the photo gates, we realized we were not going to be able to fit five rails on the keys.  The decision our team decided to make was to remove one track, and therefore we would have two tracks for the white keys and two for the black.

Solenoids

One of the big issues throughout our project was getting the solenoids to work.  Our group found extremely cheap solenoids ($3.25) and immediately went for those.  Looking back on that, we probably should have flagged that when we knew other groups were spending $16-30 per solenoid.  The first thing we found wrong with the solenoids was that they weren’t spring loaded.  Therefore, when not activated, the solenoid pin would stick out the bottom of the striker cartridge.  This would be ok because the force of the piano key pushes it back, but the problem was when we moved the cartridge to another note, the pin would get stuck in the space between the keys.  For the white keys, this was fixed easily by just gluing a washer to the end of the pin (see Figure 3).  Since the black keys were raised above the white keys, this simple solution wouldn’t work with the black key strikers.  We were able to attach a spring to the solenoid (see Figure 2), so that it would rest just above the black keys when off, and strike it hard enough when on.  Both solutions for the white and black keys worked well off the track, but putting it on the track seemed to be a different story.  It required very precise placement on top of the keys in order to strike it strong enough for a note to be heard.  For the final demo, we were able to get the white key solenoids to hit about 5% of the time, while we weren’t even able to demo the black keys because of a motor board burnout.   

Parts List

Figure 1.  Final system, without solenoids.

Figure 2.  Solenoid cartridge on the track, also shows spring system.

Figure 3.  Shows complete system for first and second track (white keys)

Marky Mark and the Funky Bunch