Re: Sustain Pedal Pneumatic Speed

A sustain pneumatic has neither the power nor the agility of the human
foot.  It is very important that the dampers are regulated perfectly
for the pneumatic to work efficiently.  The following advice pertains
to vertical (upright) pianos.  It assumes that key dip, hammer travel
(or distance from the strings to the hammers at rest, which I recommend
setting at 1-3/4" in most old uprights), lost motion and other
adjustments are regulated correctly.

There are two ways of lifting each damper off its strings.  First,
each key lifts its wippen, which lifts that particular damper with an
adjustable damper spoon.  Second, the pedal controls a long damper lift
rod, an entirely different mechanism.  If the spoons are not at least
roughly regulated, it will be impossible to adjust the dampers to the
sustaining pedal lift rod.

First, open the front and top of the piano and look down behind the
hammers at the dampers.  Depress each key slowly to make sure that
the damper begins to lift when the hammer has moved half way to the
strings.  If not, regulate the damper spoons.  If a spoon lifts the
damper too soon, *it will be impossible to regulate the dampers to the
pedal*.  I repeat this because I've seen so many people regulate the
dampers to the pedal first and then wonder why they still don't work.

Spoon bending can be difficult for the beginner, as the spoon bender
tool must be inserted through the piano action and the job must be done
by feel, not by sight.  If you are using a chubby modern spoon bender,
it might be helpful to grind the sides thinner so it fits more easily
into the tight spaces.

Second, after the spoons are regulated, depress the sustaining pedal
very slowly by foot and see if any dampers lift off their strings
before the others.  They should all lift at precisely the same moment,
as if they were made of one long strip of wood and felt.  When I
restore an action, I always disassemble it completely.  After restoring
the parts, I install the damper lift rod and dampers on the action
frame first.  Then I regulate the dampers to the lift rod before
installing the hammers.  When the hammers are already in place, damper
regulation takes longer.

This initial regulation of the dampers includes bending the wires so
the damper felts lay flat on the strings (so the top and bottom of each
damper touches the string at the same time), and also so they all lift
at the same time.  Many German pianos have an individual regulating
screw on each damper lever where the lift rod contacts it.  These make
it easier to regulate damper lift than in most American pianos without
these screws.

After regulating the dampers so they all lift as one with the lift rod,
I regulate the pedal to the lift rod so the tip of the pedal moves
about 1/4" before it engages them.  This ensures that the pedal won't
be holding the dampers off the strings.

Third, I go back and fine-regulate the spoons.

When all dampers are lifting properly, you may turn your attention to
the sustain pneumatic.  Adjust it so it moves about 1/4" at the open
end before engaging the dampers.  With the dampers regulated correctly,
the remaining travel of the pneumatic should be ample to lift them all
just a little off the strings.  Slender wedge dampers in the tenor need
a little more lift than flat treble dampers, so make sure they are
clearing the strings.  Regulate the pneumatic stop so the pneumatic
travels no further than necessary.  If all dampers positively lift
1/16" or 3/32" away from the strings, that is enough.

When this work is done and rechecked, increase the travel of the
secondary valves for the pedal pneumatic a little if necessary.  Too
little valve travel will make the pneumatic operate very slowly.  Too
much will waste vacuum, causing a surge that you might feel in the pump
as you pedal.  As in many other regulating procedures, how the
mechanism works is more important than any recommended dimension that
is only a starting point.

My book "Piano Servicing, Tuning and Rebuilding" includes pictures
illustrating damper regulation.  I'm sorry, but I am not available for
private consultation or advice by e-mail.

Art Reblitz

 [ Art's classic servicing books, "Piano Servicing, Tuning and
 [ Rebuilding" and "Player Piano Servicing, Tuning and Rebuilding",
 [ are available from the publisher, National Book Network of Lanham MD,
 [ and also via Amazon.com, bookstores and piano supply companies.
 [ His forthcoming book, "The Golden Age of Automatic Musical
 [ Instruments", will soon go to the printers.  -- Robbie