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MMD > Archives > December 2005 > 2005.12.17 > 09Prev  Next

Rebuilding a Player Piano Keyboard
By Eric Shoemaker

Hello MMDer's and to Marc Goodman.  Marc writes, in 051216 MMDigest,
"Is it important to re-bush the keys or just to rotate the metal guide
posts that the keys ride on?"

Yes, replace _both_ front and center key bushings and _do not_ turn the
pins.  Why not?  Here are several good reasons from myself, a pianist
but also a professional tuner/tech:

First of all, if a complete rebuild of the piano action (hammers,
dampers, flanges, etc.) is already planned and/or underway, why on
earth would one consider a "short cut" by turning the front key rail
pins instead of replacing the proper bushing felt?  In that line of
thinking: why replace all the hammers?  Just replace, oh, twelve of
them, maybe 51; shucks, who needs all 88 of them there keys anyway...
You get the idea.  Don't cheap out on key bushing felt, _especially_ if
you are going to play this piano with your hands aside from your feet.

The feel of _any_ piano action starts at the key!  Doesn't it?  Of
course.  Therefore, start replacing old worn out felts from that point
(the keyboard) instead of from the hammers on back and then short
cutting the #1 component in action feel and responsiveness.

Look at the front pin itself.  It's not round.  It is oval shaped,
oblong.  Now then; if this pin, driven into a carefully leveled and
planed board is turned either way, what will happen?  What, for
instance, would it do to the carefully leveled and planed board they're
set into?  Catch my drift?  Being "unround" the pins will warp and/or
crack the wood surrounding it resulting in an uneven key dip, no matter
how pretty the new green felts are.

Some piano suppliers sell a tool that literally smashes/splits the wood
on each side of the felt bushing; giving the felt a firmer grip around
the pin.  This is a way of putting off replacing the key bushings but
for what it costs to carve out a whole new keyboard later on you may
want to re-think the use of particular tool.  In all fairness to the
suppliers, okay if the piano is in the school lunchroom or in the local
hardcore spillqueen tavern; sometimes you just gotta make it run and
that's why this tool is available.  But it is not for "fine restoration

Turning the oblong pin usually will obtain incongruent results, so
that once you've mistakenly achieved proper key tightness by doing so,
that key now rubs against the next.  The oblong-ness of the pins are
consistent but the felt thickness generally is not, thereby causing
such a situation.  Also, for the most part these pins are _hard_ to
turn.  So, by applying the muscle needed to turn the pin, its original
true (straightness) will become warped.

The attention to detail in the entire keybed of players is largely
overlooked since most players like your Cable-Nelson engage the piano
action and not the key itself.  This is not only an indicator of a
half-rear-end job but absolutely deadly to the responsiveness of any
reproducing mechanisms and makes the occasional visiting pianist sound
worse than he probably is.  Remember, the sound produced is only as
good as the myriad of "married" devices that work in conjunction to
make it.  The starting point is the key, literally, no pun intended.

So either consider replacing those bushings now, while the piano is
in a state of disassembly, or in a very short time when the keys start
rattling the fillings out of your teeth.  If the rest of the project
went well your going to play what's left of the useful life of the
bushings out fast.  But don't turn the pins!

Eric J. Shoemaker

(Message sent Sat 17 Dec 2005, 12:19:57 GMT, from time zone GMT-0800.)

Key Words in Subject:  Keyboard, Piano, Player, Rebuilding

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