[pianotech] Pinbloc/plate flange gap

[Dean May]

How much instability are you seeing? If it is going sharp and flat with the
season changes then I doubt the flange gap is the source of the problem. 
 
The very first step towards stability would be a full Dampp-Chaser system
with bottom cover. Then make sure there are no HVAC vents around the piano.
Check the ceiling and floor. These beasts are very susceptible to humidity
swings and air currents. 
 

Dean

Dean W May                (812) 235-5272

PianoRebuilders.com    (888) DEAN-MAY

Terre Haute IN 47802

 
 

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From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Claude M. Harding
Sent: Thursday, January 13, 2011 4:39 PM
To: pianotech at ptg.org
Subject: [pianotech] Pinbloc/plate flange gap



A church near me has a small grand (Yamaha GA1) that doesn't stay in tune
very long.  The temperature is kept between 60 & 80, and the piano has a 

Dampp-Chaser heat bar and humidistat.

 

Two other competent tuners have also tried to tame this little beast without
much success.  The last time I tuned it (Aug. '10) I pulled the action and
checked the

mating of the pinblock and plate flange.  I used my 6-in. metal ruler (.018"
thickness) and found gaps between the pinblock and plate flange from F#3 to
A#4 and also

from B6 to A#7.  The plate flange ended at A#7, so I guess the top "gap"
runs from B6 to the treble inner rim where the pinblock is fastened.

 

How likely is it that this is the source of the instability.  If so, do you
have any suggestions for improving the situation, short of a rebuild, which
is not likely to happen.

Thanks.

 

Claude Harding

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