[pianotech] Bridge agraffes FYI

[Encore Pianos]

I have a couple of these in my service presently here in New Hampshire, and
have had others in the past.  

These bridges probably sounded pretty good in 1925 when they were new, but
as they age, they can become insanely, incredibly false.  This I would
attribute to the deterioration of the bearing surface of the maple just
behind the agraffe where the string presses into it.  The strings literally
crush the surface reducing the angle of deflection of the string as it exits
the back of the agraffe, and an insecure termination and the falseness is
the result.  I have heard these problems on a number of these agraffed
sohmers, mostly the (stupid) cupid grands.  So I attribute that to a flaw of
the design rather than an isolated incident.

Living in New England, I am in a harsh environment for pianos with dry
winters and humid summers, so perhaps I see more deterioration than you do,
in your more benign environment.  

Will Truitt 



 


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of David Love
Sent: Thursday, October 25, 2012 3:22 PM
To: pianotech at ptg.org
Subject: [pianotech] Bridge agraffes FYI

  
Attached are two photos of a Sohmer Grand bridge with bridge agraffes.  Very
interesting in that the string bears on the top of the aggraffe hole, not on
the bottom as one might expect.  In order to maintain positive downbearing
on the bridge, the bridge has a raised shelf behind the aggraffe such that
the string runs uphill to the bridge from the hitch pin area before running
downhill to the aggraffe from the short span off the front of the shelf.
The slope of the string then rises as you move toward the tuning pin
termination side.  Sadly, I did not have my bubble gauge to try and
determine the net bearing and it's definitely got me reaching for the fish
oil capsules thinking about whether a measurement of the relationship
between the hitch segment and the front segment would reveal the net bearing
anyway.  The piano sounded like caca, btw, but there were other issues.  In
spite of that, the tone was surprisingly focused.  

David Love