more heresy

[Delwin D Fandrich]

Stephen Birkett wrote:
 
> I have plenty of data on crowning and downbearing in early pianos. If
> someone would care to supply some data on modern pianos, I would gladly
> undertake to compare these two. The discussion that has been taking place
> here has condensed down to just that one question really...precisely how
> do downbearing forces and non-loaded crowns compare?

Estimates of string downforce against the bridges of modern pianos
varies from about 0.5% to 1.5% of overall scale tension. This assumes a
new piano, or at least a new board. After a couple of years--as the
soundboard breaks down--this will have settled down quite a bit.

It is generally much greater in the treble section than it is in the
bass. String deflection angles across the treble bridge can be as high
as 2.0 deg., across the low end of the bass bridge it can be as low as
0.1 deg.

String tensions vary with the size and type of piano. Through the tenor
section of a small Steinway the tensions will be about 150 to 160
pounds--in a model D they go up to 200 pounds plus. Each. Unison
tensions will be three times this amount. Bass string tensions are all
over the ballpark. Individual string tensions are higher, but there are
fewer of them per unison.

If you want the scales from a couple of specific pianos let me know. I
can send you some printouts.

--ddf