pianorye@yahoo.com writes:
<< Less friction means more power, lighter touch, faster repetition. >>
Greetings,
I must respectfully question two out of three of these. Of course, less
friction will produce a "lighter touch", but of the other two, consider:
the speed of repetition is governed by the distance the hammer is held
from the string when in check, and the return speed of the key when released. It
will be observed that in fast repetition, upon release of the key in
preparation of the next blow, the hammer does not rise from its checking height until
the jack returns under the knuckle and the key is once again depressed. (We
check spring strength by watching the hammer rise from check, but in fast play,
the hammer doesn't move upwards until the key propels it.)
It follows that the less hammer flange friction there is, the weaker the
rep. spring will be, and the slower the acceleration of the key. The leverage
and inertia found in the key is so great that the return speed varies very
little with spring strength. In practise, there is virtually no difference in
key return speed between a spring that slams the hammer upwards and a spring
that lifts it gently. All the excessive spring strength does is to make
escapement unnecessarily difficult.
As to "power", we "Jolly" well know that there is a loss of power and
tone when the hammer flange is too loose, so I suggest that power will suffer
with looser pinning, (up to a point). The tighter pinning is of major effect on
softer playing, since under a very hard blow, the felt in the bushing is
distorted enough so that only one side of the bushing is really in firm contact,(on
a hammer flange, it is the upper part of the bushing that is taking the load).
When the bushing is thus distorted, its friction from the circular
compression that we see in static testing is greatly reduced.
Regards,
Ed Foote RPT
http://www.uk-piano.org/edfoote/index.html
www.uk-piano.org/edfoote/well_tempered_piano.html
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