[pianotech] Damper Puzzled

[Joe DeFazio]

Barbara wrote:
|Well, Joe, what was it?

|Barbara Richmond, RPT
|near Peoria, Illinois
Joe writes:
Hi Barbara - thanks for asking.
It turns out that a small quantity of liquid had
spilled inside the action cavity, and had landed
on the damper tray felt, right under the two
damper underlevers in question. It had made the
felt hard just under those two underlevers.
As is normal, there was lost motion between
the tray felt and the underlevers. When the
tray was set in motion, it had enough inertia
and hardness to launch those two underlevers
forcefully. Since all of the bushings were
slightly worn, the extra " oomph" was enough
to cause the damper felts to pluck the strings.

I needled that small area of the damper tray
felt, and the two problem notes then behaved
exactly like their neighbors.
Joe DeFazio
Pittsburgh (er, Baltimore at the moment)


----- Original Message -----

|Here is a puzzler I encountered last week. Someone may get it right  
away, but it took me some head scratching to figure out, and I had  
never seen it before:


|The piano was a circa 1930 generic little american grand. I was  
called in to repair the lyre (the regular tuner is blind and does not  
do that type of repair work). Of course, assessing damper function was  
part of the job, and it was reasonably OK except for the puzzler:


|Whenever I depressed the sustain pedal (after repairing the lyre) two  
adjacent bass bichords sounded, as if they had been plucked. However,  
when I reached inside and lifted either or both of the underlevers by  
hand, there was no plucking sound.


|Just to rule out some things, the underlever leads and flanges were  
tight, the guide rail bushings were worn but not terrible, and the  
damper wires were not touching or almost touching the strings. The  
damper heads and felts were not interfering with their neighbors. The  
damper felts were old, but no more so than their quiet neighbors.  
There was no sostenuto mechanism. That's where I was when my head  
scratching commenced, as shall yours, if you're in an itchy frame of  
mind.


|Joe DeFazio


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