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STEPS PERFORMED ON OUR RECONDITIONED PIANOS
All
photos are clickable for a larger image Back
to Page 1: Basic Disassembly and Cleaning
Page 2: Action Repairs and Regulation
(Adjustment) The average
piano is comprised of thousands of moving parts. Just one damaged,
worn or misaligned part can cause problems ranging from a sticking or
sluggish key to one or more that will not play at all.
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The photo above left shows a hammer that is
crooked as a result of the hammershank twisting over time.
This can eventually become so bad that the hammer will rub an
adjacent hammer, causing the note to perform poorly or not at
all. The photo above right shows the grooves that develop as
a natural result of the piano being played. The grooves on
these hammers are not very bad, I've seen them more than 1/4"
deep, but this still needs to be addressed as part of the
reconditioning of this piano. |
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In the four photos above, we see the crooked
hammer and string grooves being corrected. The top left
photo shows application of heat to soften the glue holding the
hammer to the hammershank. The top right photo shows the
hammer being "coaxed" back into position. The
bottom left photo shows the final part of the process of filing or
shaping the hammers and the bottom right photo shows the hammer,
now straight, with the string grooves removed. After
cleaning the action with compressed air, and checking for any
other parts that need attention, the keys and action can be
reinstalled in the piano and the adjustment process started. |
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It is very important to perform the various
adjustments (called regulation) in proper order, since each builds
on the previous step. We start with measuring the distance
from the tip of the hammer to the string - known as hammerblow
(left photo). This distance changes as the hammer rest rail
felt blocks compress and when the hammers are filed to remove
string grooves. Correction, if needed, is accomplished by
adding a thin amount of felt to the felt block supporting the
hammer rest rail (right photo). |
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Lost motion is most easily defined as the
distance the key travels before the hammer begins to move.
This distance increases as the capstan felt and hammerbutt felt
wears slightly from use. This is most easily checked by
watching the backcheck (green felt in the photo above) approaching
the catcher (tan leather immediately in front of the backcheck)
and noting the amount of travel seen before the hammer assembly
starts to move. It should move just the tiniest amount
before hammer movement is detected. If it moves excessively,
or if the hammer moves at the exact time the key is depressed,
adjustment is necessary. This is one of the most critical
adjustments on the piano - too much and the hammer will
"double strike" (strike the string twice or more when
the key is only pressed once) or repetition (the speed at which a
note can be played repeatedly) will be diminished. Using a
special tool which varies depending on the maker of the piano, the
capstan is turned to adjust the lost motion. This is usually
done with the key in the piano (lower left photo) but for the
purpose of showing what the capstan looks like we took one photo
with the key out of position, showing the tool engaged on the
capstan (lower right photo). |
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As a piano is played, the felt under the
keys compresses slightly. While not always noticeable to the
naked eye, placing a straightedge above the keys will show this
wear. This will cause the keys to play and feel different
from other keys. |
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The key height is carefully measured and compared to
the original height (top left) and a block is placed under a key
to indicate the height it should be (top right). Notice the
difference, even on this nice Yamaha studio. Click on the
photo to see a larger view. |
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With the level stick indicating the amount the key
should be raised, punchings of various thicknesses are laid out to
be placed under the center of the key in order to raise the key to
the proper height. The photo to the left shows the keys now
level at the proper height. We are not done yet though... |
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Keydip, the amount of downward travel a key experiences
when being played, also needs to be checked and adjusted. Similar
to the felt under the center of the key (balance rail felt), the felt
punchings under the front of the key (front rail felt) will also
compress with use. A keydip block helps to determine if the key is
traveling the proper distance, and similar to the balance rail,
punchings are used to establish the proper amount of travel. |
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After the punchings are installed, the keys are removed
again, and the felt and paper punchings turned so the felt is on
top. Many technicians skip this part, but failing to do so will
cause clicking when the key strikes the cardboard or paper punchings
instead of the soft felt punching. It is interesting to note than
in the case of this piano, it is clear to see that the keys needing
adjustment were primarily the natural keys, toward the center of the
keyboard - the most commonly played area of the piano. |
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It is also important to check the distance at which a
hammer is stopped or "checked" from the string. Too
close and there is a risk of the hammer "blocking" or not
allowing the string to ring until the key is released (or the sound
fades with time). Too far, and the speed at which the note can be
played (repetition) is reduced. Usually, with use, the distance
increases and the backchecks are bent slightly forward (left photo) to
compensate for this type of wear. This is the case in the top left
photo, the corrected distance is shown in the top right. |
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Next - Page
3:
Cabinet and Brass Work
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