All of these are good speculations, but without testing they are metaphysics. Do you think changing the glue at the hammer joint will make the caster stop rattling? Is it possible the shock of the key hitting the keybed is what causes the caster to rattle? Can you make the caster rattle by imobilizing the system and striking the tip of the hammer with a dowel? At the moment the hammer strikes the string, it is only connected to the piano at the flange center, around the center pin, with bushing cloth that is also flexible. The kinetic energy of the moving hammer assembly passes to the string through the hammer felt, which is very flexible. The wood hammer shank is also flexible. Hide glue is hygroscopic, so its flexibility will change with the relative humidity, as well as according to the grade of hide glue used. Because of this, I question how, in typical situations, a difference of glue will make a difference in sound. If someone does an experiment, how will we test and quantify the sound differences, if any? What kind of piano? What kind of hammer? What kind of blow? What notes? With or without pedal? Susan Langer speculated that our brains are organized such that any grammatically correct sentence seems to be true. We need to be careful of that. Ed Sutton > > 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 > <BR><BR><BR>**************<BR>A Good Credit Score is 700 or Above. See > yours in just 2 easy steps! > (http://pr.atwola.com/promoclk/100126575x1222585043x1201462775/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=6680 > 72&hmpgID=62&bcd=JunestepsfooterNO62)</HTML> > >
This PTG archive page provided courtesy of Moy Piano Service, LLC