pic: CNC Router Project

[Eugene Fang]

Originally Posted by Molten

But how do they make the noise? I want to understand the physics.

I'm not 100% sure, but this is what I think:

Are you familiar with how stepper motors work? When electricity is applied to them, they go one "step," so in order to get them to move a full rotation, electricity has to be turned on and off and back on multiple (or actually hundreds/thousands) times (depending how many "steps" per rotation the motor has).

To get the motor to go at different speeds, you turn the power on and off at different rates. Pulsing something at hundreds of times a second creates different notes. For example, when you hit a tuning fork for the note "A," it vibrates at 440 Hz.

Thus, moving a motor faster means faster pulses, resulting in a higher note. And slower gives you a lower note.