Angular Acceleration in a Piano Key -Reply

[Jack Reeves]

>>> <PSLOANE@OCVAXA.CC.OBERLIN.EDU> 01/05/95
01:54pm >>>
Michael has hit upon a good point here. The ability to accelerate
a key rapidly is important to a pianist, and what hinders that ability
is the presence of too much friction and/or inertia in an action. It
is easy to measure friction in an action and to eliminate it, if
necessary, but          inertia......No one has come up with a good
way of measuring it or even begun to figure out how much is
appropriate. Touch weight deals only with static weight or
balance weight as D. Stanwood says; it only reveals how a piano
will feel during pianissimo playing and, to some degree, gives us
an idea as to whether or not a key will return sufficiently fast to
provide for good repetition. Lets have some talk about inertia
from all you techno-type people out there. And in case you are
wondering what I'm talking about, have any of you ever
encountered an action that was weighed off to reasonable
standards but still had a very heavy feel? I can almost guarantee
the piano keys were loaded with lead to achieve the "proper"
touch weight specs., adding a hell of a lot of inertia in the
process. I bet, also, that the piano was suffering from some
mechanical advantage  problems that resulted in excessive
hammer travel per unit of key travel.
Believe me, such problems as indicated above can produce real
unwieldy pianos. What do you think???

PS -- Heavy hammers add a lot of inertia, also.

Ken Sloane, Oberlin Conservatory




Yes, we have a 3 year-old Steinway D that is just as you
describe:"weighed off to reasonable standards but still has a
heavy feel".There are six leads at key one , and through most of
the bass. But there may be leverage (geometry) problems too.
The action spread is 4.41", slightly under what Chris Robinson
says it should be (4.44). I have in the past experimented with
smaller knuckles (.360" diameter) which usually resulted in lower
downweight and higher upweight, but that can throw other things
off too (or bring them back to where they should be).
This "strike-weight" thing is an attempt to measure inertia, and
apparently unravels some mysteries, but I don't know enough
about it yet. I am awaiting further posts from our friend Newton.

vince