Touch Weight

[Isaac sur Noos]

Ed,

My experience on heavily loaded keys is that they have a less large
range of acceleration available.
That seem to concur with what Don is saying us actually.
To me that mean less control on that part, and indeed the pleasing
actions are "transparent actions" not  only predictable, but also
action that react fast to instant changes in the finger velocity or
pressure.

The pianists use the mental image of the velocity of the action that
they have in their "central hand" , or unconscious hand (not sure my
definition is correct)

They expect the weight of the key near their finger to be able to
finish the stroke after the initial acceleration have been given, when
they play very fast passages, then a lot of things happen like the
rebound of the key on the punching. Again, I consider that more lead
near the balance is slowing those, anyway at the speed concerned.

The fact that the leads are subjected to gravity is probably why they
are felt like "braking" the keys , while this may sound an agreeable
sensation for non professional pianists, I am certain this is more
felt like a limitation by them, a piano action is not a gyroscope !

Best regards

Isaac OLEG
-----Message d'origine-----
De : caut-bounces@ptg.org [mailto:caut-bounces@ptg.org]De la part de
Ed Sutton
Envoyé : samedi 20 décembre 2003 22:09
À : College and University Technicians
Objet : Re: Touch Weight

Jim-

Weakening of keys is certainly a consideration.  When I remove leads
I'm ususally
removing them from the front of the key where it doesn't matter much,
and I don't
use the largest diameter leads near the balance rail. One could argue
for Jiffy
leads here.

I think it will be interesting to quantify inertia rather than just
trying to add
weights closer to the balance rail.

My intuition (for what that's worth!) is that reduced key inertia can
have a
significant effect on the speed with which the key rises, i.e. produce
the sense
that "the key stays with the finger."  I don't have any equipment to
measure this,
so can only rely on the pianist's response.  (I think I know someone
in Tennessee
who has the equipment to test this!)

And I will appreciate any reduction of key thump.

Best wishes,
Ed Sutton


----- Original Message -----
From: "James Ellis" <claviers@nxs.net>
To: <caut@ptg.org>
Sent: Saturday, December 20, 2003 2:31 PM
Subject: Touch Weight


> I have been reading the numerous "Touch Weight" posts on this list,
and I
> told myself I was not going to get into this one.  But now I will.
I'll
> just mention a few generalities, and I'll suggest that a few of you
stop
> and think a minute before you haul off and do something you might
regret
> later.
>
> Touch weight and inertia are NOT the same thing at all.  "Tough
weight" is
> merely a measure of static force.  "Inertia" is a dynamic quantity.
>
> Inertia is proportional to mass, but it is proportional to the
square of
> velocity.  That's why putting more leads closer to the center of the
keys
> will result in less "KEY" inertia.  You will have to use more lead,
but the
> "key" inertia will be a little bit less.  However, the keys are NOT
where
> most of the total action inertia comes from.  It comes from the
hammer
> heads out on the ends of the shanks, because that's where the (mass
x
> velocity squared) is concentrated.
>
> All I'm saying is that moving the leads closer to the centers of the
keys
> is not going to buy you very much, because that's not where most of
the
> total action inertia is coming from in the first place.  What it
will do is
> weaken the keys, especially if you drill more holes, plug holes,
etc.
>
> It will also do something else you might not have considered.  It
will
> slightly reduce the amount of percussive noise of the key fronts
hitting
> the front rail punchings, because you will be getting the
concentration of
> mass in the keys farther away from the key fronts.  Again, this
effect will
> be slight, at best.  It won't amount to very much.
>
> Those two things are about all it will do for you, other than just
making
> the keys heavier in the middle.  So, before you haul off and re-do a
whole
> set of keys, drilling more holes, adding more leads, plugging holes,
and
> moving all the leads closer to the center, remember:  It won't buy
you very
> much towarding lowering the overall action inertia, because that's
not
> where it's coming from, but it will definitely weaken the keys.
>
> Merry Christmas,  Jim Ellis
>
>
> _______________________________________________
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>

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