[pianotech] Totally glueless

[Ron Nossaman]

On 1/31/2013 6:06 PM, Euphonious Thumpe wrote:
> Please allow me to point out, Kind Sirs, that the function of simple
> tuning fork exhibits those traits of energetic
> transmission/transmutation that some members of this list seem to
> discount as fantasy: specifically, that when the ball at the end of a
> tuning fork stem is simply, gently pressed (with no solid mechanical
> coupling) against some object (and with the briefest of all possible
> contact points) energy is transmitted from the laterally oscillating
> tines well ABOVE that point TO that object; which then transmits them to
> the the surrounding air, resulting in sound of a louder volume than the
> tines alone impinging on the air create. And that this phenomenon will
> transpire even if the object thus pressed against is a distinctly
> non-diaphragmatic -- as we normally conceive it -- one, such as a cube.
> I thus find it implausible that such an easily observed phenomenon would
> not find expression in a structure as large, solid, and rife with
> vibratory excitement as that which a piano presents.

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.

Ron N