Keybed Warping

[Clyde Hollinger]

Cliff Lesher wrote:
> 
> I am wondering if anyone has seen this before:
> 
> The piano:  Chickering console, Serno 185664, Mfd ~1943.  Located near
> corner of inside and outside walls.  Outside door nearby.  House has no
> a/c.
> 
> Last winter, I was asked to look at this piano because, "the keys
> weren't working right."  During discussion, I learned that the piano had
> been worked on when the owner lived in NC.  The owner thought the
> problem might have been caused during the move from NC to PA.
> 
> My inspection revealed the key height to be extremely high.  The keys
> bottoms were above the keyslip, they were no longer "engaged" by the
> front-rail pins, and the dip was nearly 3/4".  It was no surprise that
> there was severe hammer blocking.  These conditions were worst at the
> center of the keyboard and tapered toward each end.  The keyboard crown
> was readily apparent, looking like an exaggerated example to demonstrate
> the concept.
> 
> I concentrated on the balance rail and noticed that the punchings were
> "normal" but the rail was shimmed up about 1/8".  Taking the wholesale
> approach, I removed the shims to see the effect.  After doing so,
> everything dropped right into place.  All parameters were generally
> correct.  I closed the piano and left, but not without a feeling that
> there might be more to this.  I communicated this to the grateful owner.
> 
> Sure enough, the follow-up call came in mid-July, on perhaps the most
> humid day of the year.  This time the symptoms were just the opposite:
> zero dip, etc.  My conclusion was that the humidity cycle affected the
> keybed causing it to crown toward the floor in summer and return to
> near-flat in winter.  The shims went back in for the time being.
> Humidity discussion followed.
> 
> Questions:
> 
> As stated earlier, has anyone seen this?
> 
> Along with changing the location of the piano, will a climate control
> handle this magnitude of change "outside the cavity?"
> 
> Any other ideas?
> 
> Cliff Lesher
> Lewisburg, PA

Cliff:

I am a fellow Pennsylvanian and I have never seen anything approaching
this amount of change.  I can't quite imagine that this is due to
humidity swings alone even if the un-airconditioned house is by a stream
in the woods and is heated by a woodstove next to the piano (or a heat
source behind/under the piano).  But maybe it is.  I still have lots to
learn.

If this were my client I would probably recommend a complete
Dampp-Chaser installation, in this case possibly with a 5F or 7F
dehumidifier under the keybed, stressing that this is the _first_ step
in trying to solve the problem.  I might also go back to visit the piano
every two months or so, take some measurements, look things over.  When
you discover the solution, I for one would be interested in what you
learned.

Clyde Hollinger, RPT
Lititz, PA