Week 8: Refine, Refine, Refine

Last week, we were able to demonstrate that our bass guitar was able to physically play all 20 of the notes we had planned for it to be able to handle. This week was all about refinement. During last weeks lab, when we demoed the range of our instrument, we asked ourselves "what can we do to make this instrument sound and play with better accuracy and more enjoyable timbre?" Here is some of what we came up with.

Upgrading the Strumming Mechanism

The design we had used to strum the bass has largely gone unchanged throughout the design process. What goes into strumming a bass is not conceptually hard; just have a pick move back and forth over the string to simulate upstrokes and downstrokes. We had implemented a structure that held four solenoids that had plastic, 3D printed rod connected to guitar picks that would motion back and forth, strumming the pick when powered on and off.

This design was mechanically sound, however, there was a major issue with heat. The solenoids that we used to build the strumming mechanism was small and poorly ventilated. As they were powered for extended periods of time, they would heat up to a point where the 3D printed encasing would begin to warp. This was not good for long term use. A less pressing issue was that we wanted more force behind the strumming. The solenoids we were using generated enough force, but we felt that it would be more consistent with a stronger solenoid.

The solution we came up with was to use four more of the stronger solenoids that we used for fretting as strumming solenoids as well. These solenoids, despite generating more force, actually run cooler. They are better ventilated and can handle high power for extended periods of time without generating too much heat. We also attached mini-heat sinks to each individual solenoids to further reduce the chance of heat becoming an issue for the refined design. In the end, the final revised structure for strumming looked like so:
Final Strumming Mechanism

Tweaks to Fretting

Mechanically, we did not touch anything with the fretting mechanism. Instead, we altered some of the code. The biggest thing we added was a slight delay between the placing of a fret and the strumming of the string. This helped to make the strummed note ring out more clearly. We also tweaked the gain on the bass to produce a better, more enjoyable sound.