Bridges: Chew on this

[Don Mannino]

Jim Harvey wrote:

>>     The question then becomes: since all strings on all pianos have a
>>     stagger when crossing the bridge, what determines why one manufacturer
>>     staggers strings to the left and another staggers them to the right?

Here are my thoughts on the matter:

1. On a treble bridge the angle is usually set so that the force of the strings
push the bridge pins toward the center of the bridge's width. If the strings
were deflected the other way, the pins would be pushed outwards, being more
likely to split the bridge.  This is especially true in the lower half of the
long bridge.

2. This MAY (speculation time) have a sonic benefit by applying a "twisting"
force on the soundboard. I have no idea, actually, but I can imagine that the
direction of this force might affect the tone.  Might be an interesting topic to
discuss.

3. On a bass bridge with an apron, the twisting force on the bridge could be
more critical because of the mechanical advantage the apron creates. If a
manufacturer uses the two-direction scheme (where the direction of string offset
is reversed between the double and single string unisons), it is more likely to
be on bass bridges because this scheme tends to cancel the twisting forces, and
the force applied to bass bridges by the sideways deflection of the strings
tends to be more perpendicular to the bridge than in the tenor bridge. (there's
a sentence for ya!)

Don Mannino
74473.624@compuserve.com