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MMD > Archives > May 2012 > 2012.05.26 > 07Prev  Next

Animated Keys of an Upright Pianola
By John A. Tuttle

Hi All,  Jim Perkins wants to know about any linkage between the player
action and the piano action that causes the keys to move when the music
roll is playing.  Jim is correct in his observation that there doesn't
appear to be any 'connecting' linkage between the player action and the
piano action in upright player pianos.  And just so we stay on track
for the moment, let's qualify the situation.

When the player stack (or windchest) is located above the piano keys,
and the striker fingers attack the wippen or the abstract (the piece of
wood that's connected to the wippen, at the top, and rests on the key
capstan, at the bottom), the force that causes the keys to move is
"gravity".  In fact, the keys of the piano are specifically weighted
such that they will 'fall' down (at the front) when the weight of the
piano action is removed by the action of the striker finger lifting the
wippen (or abstract) "up".

There are a number of different ways to transfer the energy of the
collapsing striker pneumatic to the wippen.  The most common way is
to attack the wippen directly via a flexible wooden finger which is
connected to the striker finger by a piece of wire or wood.  The less
common way is to attack the abstract directly using a wooden striker
finger that's screwed onto the striker pneumatic.

In the vast majority of player pianos manufactured in the early part
of the 20th century (approx. 1904-1932 ) the stack in upright player
pianos was located above the keys.  However, there were a few
manufacturers who elected to locate the stack below the keys.  In
those units, the energy of the collapsing striker pneumatic is used to
'push' the piano key 'up' at the back of the key.  But, there is no
'physical' connection between the action of the player and the keys.

So, presuming that the piano that Jim is dealing with has a player
action that is located above the keys, the only way to get the keys
to move when the roll is played is to change the 'balance' (or weight)
of the keys in such a manner that they will 'fall' down (at the front)
when the weight of the action of the piano is removed.

By the way, the weights in the keys in upright player pianos are
generally located in the back half of the key, not the front half.
This is because the front half of the key is almost always heavier
than the back half, even if the balance point (where the center rail
pin is located) is positioned precisely in the middle of the key (which
is seldom the case).  Also, please understand that changing the weight
of the keys will directly effect the touch weight of the piano action
-which has been precisely determined by the manufacturer.

My point in making the above statements is that it's fairly easy to
remove enough of the lead in the key to change the balance such that
it will 'fall' down at the front.  However, you must bear in mind that
you're also changing the geometry of the action.

Also, it is true that some (actually many) player pianos are equipped
with a device called a 'key lock', which is designed to prevent the
keys from 'falling' down when the player action is playing the piano.

In patents I have found, one or more of three reasons are given to
justify its existence.  One, to reduce unnecessary wear of the felt
piece at the bottom of the abstract.  Two, to prevent people from
playing the piano when the player action is playing the piano.
Thirdly, (and in my opinion the only logical reason), to increase the
repetitive capability of the piano.

To me, this is the most logical reason because it deals with measurable
forces that actually do effect the repetitive capability of a piano
action.  In fact, a note in an upright piano can only be struck a
second time once the jack gets back underneath the butt, and that
doesn't occur until the action comes to its full resting point.

Now, since the keys in most upright players are weighted such that
they will 'fall' done when the player is being used, the weight of that
key must be overcome by the piano action before the action will 'reset'
itself.  If the weight of the key is removed from the equation, the
note can reset faster.  Ergo, the repetitive capability of the piano
action is increased.

John A Tuttle
Brick, New Jersey, USA

(Message sent Sat 26 May 2012, 18:29:04 GMT, from time zone GMT-0400.)

Key Words in Subject:  an, Animated, Keys, Pianola, Upright

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