Ed writes:
<< > My guess is that the flexing of the hammer shank, and the intended
> flexibility of the wool hammer, exceed by far any difference in
flexibility in the glue joint. And please remember that the jack is not
driving the
> hammer at the moment it contacts the string, the hammer is moving because
of its own inertia >>
Greetings,
When the hammer hits the string, there is an instantaneous shock
wave that travels through the entire assembly, all the way down to the casters
. I have actually had a customer complain about the ball bearing casters
on her 1885 Steinway rattling on FF blows. (this is also why a loose knuckle
joint, or flange screw will click on hammer to string contact).
This wave has some effect on the tone, I imagine because of the
impedance of the system while the hammer is in contact with the string. The shank
and hammer assembly vibrates during the dwell time of string contact, so
their entrainment is influenced by everything in them. Whenever energy passes
through a different material, it loses some of its strength, so I think the
glue joint is a factor, if not strictly in its influence on the energy
wave's path, then perhaps via a damping effect.
There is good reason not to use pvc-e glue to attach the ribs to the
soundboard, no?
My guess is that the importance of the glue depends on where in the
scale, i.e., the high treble might benefit from a harder glue, due to the
frequencies involved. I don't think I want anything more absorptive in the
hammer/shank structure than necessary.
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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