Pinning on new flanges

[Isaac OLEG]

Hello,

Good analysis for sure, and remeber the weight of the arm/shoulder  of
the pianist is way too much in regard of the weight necessary to
produce notes, so a too light action oblige to use more muscular
energy and less weight.

The same idea why using Vj lube or graphited grease on the butterfly
spring, helps to avoid too much freenes of the spring at the lever's
side, and keep enough tension on the repetition side even when pinning
of the hammer is getting too loose, obliging us to lessen the spring.

Now we can talk about graphite grease (to wich I am opposed because of
the acidity that corrode the spring)for at last 50 post !

Best Regards.

Isaac OLEG







-----Message d'origine-----
De : V T [mailto:pianovt@yahoo.com]
Envoye : dimanche 29 aout 2004 22:54
A : pianotech@ptg.org
Objet : Pinning on new flanges


Hello Friction Thread,

Here is an additional view to get the conversation
heated up:

The musician has roughly 10 mm of key travel to apply
the force to the key.  The choice exists of where on
the key to push, and how to time the force.  If we
plot a function of finger force vs. time, we will see
that the player controls his touch by modulating this
force during the travel of the key.  There is a
feedback loop at work and the player integrates the
force to get the proper momentum into the hammer head.
 He may start with a higher force to get the static
friction out of the way, but then he might lessen the
force in order to create a soft blow.

The following assumes that the balance weight is kept
the same when comparing the low friction to a normal
friction action.

All mechanical systems have a "damping ratio".  This
is a ratio of stored to dissipated energy.  Control
basically amounts to being able to impart just the
right amount of momentum to the hammer.  A mechanism
with a low damping ratio (little friction) is harder
to control because a mass set into motion without
friction will continue to move freely.  The player has
no means to slow the mass down if he initially presses
too hard on the key.  His skills then consist of not
pressing too hard, or quickly backing off in case he
did press too hard.  This is exactly what a
"frictionless" action requires - the ability to change
finger force in an incredibly short period of time.
Again, he has only 10mm of key travel during which he
can distribute the force.  For best expressiveness,
the musician would probably like to have as much of
those 10 mm available to modulate the pressure without
feeling that he is moving the key stick through
molasses.  If he doesn't have the physical ability to
reduce the force quickly, he will feel that the action
is "temperamental".

The situation changes when very fast playing is
required.  The requirement for a precisely controlled
dynamic level may give way to the need for speed.  A
fast (low friction) action becomes advantageous.  I
think that pianists who like to play fast pieces and
have phenomenal control over their touch may prefer an
action with very low friction.  They have the ability
to put just the right amount of energy into the hammer
in the shortest amount of time, basically using the
initial stage of the key movement to send the hammer
on its way with the precise amount of momentum.  Since
they did all the work in the initial stage of the key
movement, they are free to quickly move on to the next
note.

Vladan



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