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The Owner's Guide to Piano Repair

Focus On: Refelting the Keybed

Information provided courtesy of:
David Boyce, BA
Piano Technician
Tel: 01475 639915
Mobile: 07714 959806
David@piano.plus.com
www.piano.plus.com

The quiet operation of the keys of your piano depends upon three sets
of felts (front rail punchings, balance rail punchings and back rail cloth) that
function as cushions. Besides their ability to absorb unwanted sounds, these felts
are also important in determining both the height of the keys and the depth of the
keystroke. As the piano is played over the years, however, these felts become thin-
ner and harder. The keybed felts of your piano have worn to the point where
removal and replacement would benefit both the touch and appearance of
your piano.

The following commonly asked questions have been answered to give you the
information you need in order to decide whether or not to have the keybed of
your piano refelted.
What are the most noticeable effects upon the performance and appearance
of the piano that are caused by worn keybed felts?
As the keybed felts harden and wear thin the keys become uneven in height
from note to note. Also the amount of downward stroke (key dip) begins to vary.
This variation results in an action which has an uneven touch. A perfectly level set
of keys with a uniform amount of key dip is essential to a piano action which is
performing up to its potential.
In addition to the negative impact upon the touch of the piano, uneven keys
that result from worn felts give the keyboard of the piano an unattractive and un-
cared-for look, making the piano less inviting to play.

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The thickness of heavy backrail cloth equals that of six dimes.

Is the felt used for this job out of the
ordinary at all?
Very much so. As illustrated in
the photo above, the felt used for
backrail cloth (as well as balance rail
and front rail punchings) is a very
thick, dense felt that is designed to
stand up to decades of constant use.
Keybed felts come in a range of
thicknesses, so that the original size of
the felt installed at the factory may be
duplicated. Paper and card punchings
as thin as .002" are used under the
felts for final adjustments necessary
for level keys and even key dip.
Thinnest and thickest front rail punchings.

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Is this work best done in
the home or the shop?
It depends on whether
other related work is to be
done as well. If keytop re-
covering, key rebushing or
other time-consuming jobs
are going to be done at the
same time, transporting the
necessary parts to the shop
would make sense.
If only the keybed
felts are going to be re-
placed and necessary adjust-
ments to the regulation of
the piano made, it might be
possible to schedule the job
to be done in the home.
To accomplish the re-
placement of the keybed felts, the front rail felts and balance rail felts are first re-
moved to be discarded. Measurements will be taken so that the original thickness
of the felt may be duplicated. The backrail cloth is typically glued in place and is
somewhat more difficult to remove. (Along with the cloth, any glue adhering to
the keyframe needs to be scraped off to give a clean surface to work with, as
shown in the photo above.)
Paper and cardboard punchings which are used to level the keys and set the
amount of key dip have typically deteriorated as well and ordinarily need to be
discarded and replaced.
Are there other related repairs which might be recommended at this time?
Yes. At the minimum keys will need to be releveled and the key dip reset.
Better yet, a full job of regulating the piano would help bring the performance of
the piano back into proper condition. Also a thorough keybed cleaning is usually
recommended at this time.
Related areas of repair should also be considered. The condition of the front
rail and balance rail key pins should be carefully looked at. If corrosion is seen,
they should be polished or replaced. The keys themselves should be examined for
excessive wear to the key bushings. Keytops may need to be replaced as well. An
overall job encompassing all of these factors can do wonders for an older piano.

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New set of keybed felts in place.

"In business to bring your piano to its full potential."

Please advise me when you wish to have this repair professionally done.
David Boyce, BA
Piano Technician
Tel: 01475 639915
Mobile: 07714 959806
David@piano.plus.com
www.piano.plus.com

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Technical Info 9 re-felting keybed

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Technical Info 9 re-felting keybed