Exercise: Motor Music

In this exercise we will design and fabricate a simple musical instrument driven by an electric DC gearmotor. The overall project objective is a sound-producing device which combines autonomy and user interaction. The technical objective is creating a reliable actuation scheme using a gearmotor.

There are several directions you might consider.

  • using a motor as a source of energy

  • using a motor to create timing

  • enabling the user to control the motor

Objectives

The overall objective of this exercise is to design and fabricate a freestanding device which actuates a sound-producing process using a DC gearmotor.

The goals of this exercise are that you should be able to:

  1. Design and fabricate an object which can create sound.

  2. Design a structure to support the sound element while allowing one or two degrees of freedom.

  3. Reliably mount a DC gearmotor in an assembly.

  4. Design a motion transmission to couple motor shaft rotation to the sound process via mechanism.

  5. Design a multi-part assembly including joinery.

  6. Laser-cut parts, assemble, test, and iterate.

References

Gearmotors

A principal technical objective is gaining design experience with gearmotors. These actuators can provide continuous rotation in either direction at variable speed and are useful for energy input and motion control. In this exercise we are simply powering them for constant rotation.

Please do not glue anything to your motor shafts; use the Lab Part 1885 as per the motor hub guide. Please face-mount your motor using M3x10 screws as per the mounting guide.

Please note that unlike the hobby servos, gearmotors do not have any position sensing, so moving them to specific positions would require the use of additional sensing, usually in conjunction with microcontroller programming and a digital motor driver.

Deliverables

  1. Live in-class demo of your device

  2. A short report posted to the shared drive including:

    1. a short text statement reviewing your intent and outcomes in about a paragraph

    2. one or more photos

    3. a brief video (e.g no more than 30 seconds)

    4. A dimensioned drawing of the assembly and key parts. The purpose of the drawing is to convey the idea, the scale, and critical mechanical elements, not communicate a complete shop plan; it is acceptable to omit some minor parts.