rocking bridges

[Ron Nossaman]

Sorry about this gang, but one more quick demo I tried in the shop today to
illustrate a point.

Fully strung piano, up to pitch. A beam spanning the rim, with a laser
pointer mounted to it instead of a dial indicator. A piece of mirror lying
on the strings across the bridge top in the middle of the long bridge,
reflecting the beam to the ceiling. Push down on the strings of the
adjacent unison, the beam moves slightly toward the front of the piano.
Pull up on the strings, the beam moves slightly toward the front of the
piano. It's not much, but the bridge rocks forward each time. The higher
the ceiling, the greater the movement and the easier to see.

Good night.

Ron N