[pianotech] Totally glueless

[Ron Nossaman]

> The tines of a sounding tuning fork move in opposite directions from one
> another, the tips describing a curve. It's not an arc, and I don't know
> what the curve is called, but it is a curve. When the tines are
> parallel, the fork is at it's longest overall length. When the tines are
> either closest together, or farthest apart, the fork is at it's shortest
> overall length. The difference isn't much, but there is a difference.
> This cyclic difference in length causes the handle tip to cycle up and
> down perpendicular to the tine movement. Press the handle against
> something solid and it cyclically pushes against the object, moving it
> slightly, displacing air, and producing a tone that is twice the
> frequency of the fork since there are two length change cycles for each
> tine cycle.
>
> That's it.


One more thing, interesting if useless. Sound a tuning fork and slowly 
rotate it next to your ear. As it rotates, it will become louder, then 
silent as the pulses from each tine either reinforce or cancel each 
other as they reach the ear. Tuners hardly ever use forks any more, and 
most don't know how they work.

Ron N