Bridge pin angles

[Ric Brekne]

Phil writes

>/RicB writes
>This is simply incorrect.  True enough when a soundboard and bridge 
/>/become so damaged that there is no positive bearing, or that bearing 
/>/is lacking relative to some portion of the bridge surface, then 
/>/seating becomes a very temporary fix.... increasingly so with the 
/>/amount of damage. But this does not cover the cases when strings 
/>/need seating despite positive bearing all around.
/>/
/>/RicB
/
If humidity increases and the bridge moves up and the string does 
not, then the cap will be crushed locally by the pin.  When the 
humidity decreases then the cap will move back down and once again 
the string will not.  So there will be a gap between the string and 
the bridge cap at the edge of the notch, even if downbearing is 
positive.  So, you have a case where the string needs to be seated 
despite positive downbearing.  I don't see why this case isn't 
covered.

Phil F

By reverse logic, if humidity increases and the bridge moves up and the 
cap does not experience crushing, then the string obviously has moved... 
for whatever reasons. This happens quite a lot actually. If it didnt you 
would see severe notch indentation the very first season change... every 
time. In actuality newer pianoes usually have only slight indentations, 
and much of these are caused by over eager string seating proceedures.

The whole point of Rons argumentation is that the bridge surface pushing 
up against the clamped strings results in the bridge surface being 
crushed to the point of forming an indentation that lies under the  line 
drawn from the strings highest point on the bridge to the front 
termination. When this happens there is negative bearing at that 
indentation.  If on the other hand there IS positive bearing at this 
point AND the strings still need seating... his theory fails to explain 
how this can be... and indeed claims the condition is impossible. Since, 
however, it is clearly observable that this condition DOES exist and 
quite frequently...  I have to disagree with him :)

Cheers
RicB