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MMD > Archives > February 2000 > 2000.02.09 > 09Prev  Next

Humidity Control & Loose Tuning Pins
By D. L. Bullock

I am addressing Andy Taylor who bemoaned the winter loose pins from
lack of humidity.

All pianos are affected by humidity fluctuations.  The most often
affected is the soundboard and its crown.  If you ever wondered why the
piano went out of tune in one section but not another, consider when a
soundboard takes on moisture the crown grows up stretching the strings
tighter.  When it gets very dry the soundboard crown goes down as the
wood shrinks.  This loosens the strings.  All this movement often
affects only the center area of the keyboard.  A new soundboard or
newly recrowned board is less susceptible to moisture since it is under
much more pressure than an old shrunken and cracked soundboard.

I found it fascinating, when I have built soundboards, that when you
have crowned the board and glued on the ribs, you can take the board
out of the dry box, lay it on the table and just watch the crown belly
rise.  It does it so fast you can actually watch it move.  This is when
the board is not glued down to the piano timbers yet, so it moves the

Anyway, when the board moves inside the strung piano, it moves more
in the center where there is less pressure.  Near the edges of the rim,
the soundboard is glued down and cannot move as much.  I often find in
mid-winter tunings, that the piano is low in pitch but when I get to
the top octave or two those are still in tune.  In the damp spring and
summer the opposite is true, with the center section higher in pitch
and the top treble in tune.  The bass strings are less and less out of
tune as one goes down in pitch.  It takes so much movement to change
pitch in the heavy bass strings that they usually do not go out of tune
as fast as the rest of the scale.

Pin blocks are also susceptible to moisture.  But the only pins that
get loose when it's dry are those that are a problem anyway.  Early on,
I was like Andy, and when I found a loose pin I declared the piano
needing restringing, and that is true to a point.  It is the beginning
of the end of the piano's life span.

But I find that there are just too many pianos to restring and you
can't get to them all and the customer won't always pay for the
complete rebuild.  In such cases I just repin the loose pins.  I know
that is what the hacks do, but I am going to get a few more years out
of the piano and perhaps by then I will have room on my schedule to
restore the whole piano.

To repin just one or two loose tuning pins, loosen the pin just enough
to pull the becket out of the pin and unscrew the bad pin.  If it is
too loose to unscrew then use the vise-grips and pull it out.  Stick a
screwdriver blade through the loose coil in the string and, using one
hand on the handle and one on the blade, pull toward you or away from
the hitch pin until you have removed the coil.

Do not try to straighten out the curled end.  In some cases the wire
is brittle enough that you must snip the becket off and put in another
one.  Use the same technique as you use when stringing and use the
stringing crank to put a neat new coil onto a tuning pin, one or two
sizes larger than the old one.  Now drive the pin into place, just as
you would were you totally stringing the whole piano.

I prefer this to using the pin dope.

As far as preventing these problems, the best idea is to keep a
humidifier in the house, and you must have an hygrometer to set on
your piano so you can always know how much humidity it is getting.

D. L. Bullock    Piano World    St. Louis

(Message sent Wed 9 Feb 2000, 18:27:52 GMT, from time zone GMT-0800.)

Key Words in Subject:  Control, Humidity, Loose, Pins, Tuning

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