Key Excursion

[David Nereson]

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org]On
Behalf Of Jon Page
Sent: Friday, April 14, 2006 10:15 PM
To: pianotech at ptg.org
Subject: Key Excursion

Has there ever been established an arc in which the key optimally rotates?

At what point in the keystroke should the surface of the key be, say,
parallel
to the floor/keybed.

Should the key fully dip at level or should it traverse level at
letoff or at damper lift.

Does key length factor in, either vertical or grand. Is there an
association
between touchweight measurements and dynamic playing.

Just curious as to opinions. I have mine of course.
--

Regards,

Jon Page
	What do you mean, has there been an arc established in which the key
optimally rotates?  It's determined by the balance rail pin and the length
of the key; it's different on different pianos, depending on the design.
Now the distance the wippen travels is determined by the distance of the
capstan from the balance rail pin (and, to a much lesser degree, by the
amount of key dip).  So yes, of course key length factors in.
	Since the excursion of the key is only 3/8 of an inch, and in better
pianos, the keys are balanced (weighted or not) with the action parts for
optimum inertia, I don't think it matters a whole lot whether the key is
level when it's up, down, or in the middle of the stroke.  Say the key
were level when at rest position.  Then when bottomed out, it would slant
toward the player.  Now, if you put something under the front legs so the
key was level when down, it would now slant up toward the player when at
rest.  Would the action play as well?  Would it be noticeable?
Now, in an upright, the piano should be level not only across the lid (or
keys), but front to back, for even distribution of weight and so the back
or plate is not being twisted.  If the piano leans backwards, gravity
fights the return of the hammers and the butt springs have a harder time
doing their job.  If it leans forward, then gravity fights the hammers'
excursion to the strings.  Both of these effects are very slight, but
maybe they could make a difference to a very sensitive player.  (?)  But
in a grand, because of the action's being horizontal, I think the
difference would be negligible.
And of course there's an association between touchweight and dynamic
playing.  That's why we fool with it (try to make it better) in the first
place.
	--David Nereson, RPT