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MMD > Archives > October 2007 > 2007.10.16 > 05Prev  Next

1970s Aeolian Player Piano with Plastic Valves
By John A. Tuttle

Hi All,  Deane Wiley wrote [071001 MMDigest]:

> When the hammers are resting on the top back of the keys, how much play,
> if any, should there be between the back of the hammer and the top
> of the wooden button attached to the wire coming from the pneumatic?

I'm not sure if I already replied or if anyone answered the question.
I'd like to start by saying that I know of no modern Aeolian player
that has the striker pneumatics connected to the keys.  In all of the
modern Aeolian players, the striker pneumatics strike the underside of
the keys via a wire and a wooden button which are connected only to the
striker pneumatic.  The wooden button hits a piece of felt which is
glued to the bottom of each key.

In essence, there is no way to answer Mr. Wiley's question because the
wooden button at the back of the key is not connected to the pneumatic.
It's connected to the wippen in the piano action.  (More accurately,
the button is screwed on to a wire which is also screwed into a wooden
elbow at the other end.  The other end of that elbow is connected to
the wippen.)

The only Aeolian players that have the button at the back of the key
are the players with a drop action (where part of the piano action is
below the keybed).  The buttons are used to adjust out the lost motion
that occurs as a result of using the piano (or wear).

Removing the lost motion between the striker pneumatics and the keys
is, for all intents and purposes, accomplished by raising the stack.
I will be creating yet another web page at to fully
explain the details involved in properly adjusting both lost motion
adjustments.  However, with regards to the lost motion adjustment
in the piano action, the correct answer is "almost zero".  And, since
I realize this is a subjective answer, let me explain.

As with any drop action (or upright for that matter), adjusting the
lost motion to 'zero' is asking for trouble.  The main reason this is
true is because the wood might swell due to an increase in temperature
and/or humidity.  If that happens, the jack will not be able to get
back under the butt quickly or fully.  Should that happen, the jack
will not be resting firmly under the butt, and the power of striking
the key will not be transferred from the jack to the butt properly.
This possible problem is even worse in a drop action than an action
that rests above the keys because of all the extra weight and angular
changes in the drop action.  (Another way to say it is that the keys
are pulling the wippen up as opposed to pushing the wippen up.

That being the case, it's wise to back off the lost motion adjustment
in a drop action by a few thousandths of an inch.  This is best
accomplished by turning the button clockwise until the hammer just
starts being pushed away from the hammer rail.  Then the button is
turned counterclockwise until the hammer comes back to rest on the
hammer rail.  Then the note is struck firmly a number of times to set
the button back in its hole.  After that, the back of the key is
depressed by hand to insure that the hammer is indeed resting on the
hammer rail.  If it moves even the slightest amount, turn the button
further counterclockwise until nothing happens when you depress the
back of the key.

Next, touch the front of the key ever so lightly.  If the hammer moves
with the slightest of pressure, the lost motion adjustment is most
likely too 'tight', or too close to 'zero', or at zero.  When correctly
adjusted, there should be a very slight sponginess to the feel of the
key.  And, if you watch the piano action from above while touching the
front of the key, you will see the back check move ever so slightly
before the hammer starts moving.  This indicates that there is a very
small amount of lost motion between the jack and the butt.

Lastly, when correctly adjusted, only a trained technician should be
able to tell that the lost motion exists.  It should not be noticeable
to the pianist.  If it is noticeable, the adjustment is not 'tight'
enough, and further adjustment is needed.

John A Tuttle
Brick, New Jersey, USA

(Message sent Tue 16 Oct 2007, 15:50:02 GMT, from time zone GMT-0400.)

Key Words in Subject:  1970s, Aeolian, Piano, Plastic, Player, Valves

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