This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Dale, from mechanical view hammer stiffness does not simply follow hooks law. = Hammer reaction force is increasing nonlinear with felt compression.=20 Hammer stiffness can be described as a complex value by its nonlinear = elastic modulus. The real part is the reaction force on the string and = the imaginary part is the damping loss.This phenomen is called = "hysteretic damping". Measurements on hammers parameters has been done by Anatoli Stulov, = where he measured felt stiffness and rebound time.He found differences = of a factor of about 100 % in the rebound time between different new = hammer sets made by diverse makers. (Abel, Renner, Imadegawa)=20 The rebound time is in correlation with the felts inner friction losses = (or imaginary part of elastic modulus) , not to stiffness. A high quality felt has a low rebound time. Laquering, heat and = overpressing of the felt increases not only stiffness, but also the = rebound time (and therefore losses), since the fibres become glued = togehter.=20 regards, Bernhard ----- Original Message -----=20 From: Erwinspiano@aol.com=20 To: pianotech@ptg.org=20 Sent: Tuesday, May 11, 2004 3:00 AM Subject: Re: Lacquer fight! Lacquer fight! In a message dated 5/10/2004 1:03:52 PM Pacific Standard Time, = Richard.Brekne@grieg.uib.no writes: Hi Bernhard. An interesting point that I see no one has really answered too. Cheers RicB Hi Bernard Bernhard Stopper wrote: >Hammers parameters are not only stiffness/springieness. >A big influence on sound quality is the amount of the energy that = is lost >due to the hammers inner friction of the fibers. >>> Which no doubt is in direct correlation with it's inate stiffness = /sprininess or lack of it. A good felt quality has a >high ability of rebounding a big amount of the input energy.=20 Providing it got adequate & appropriate pressing resulting in = tension & compression. It seems logic >that this rebounding ability on a high quality hammer is reduced by >lacquering.=20 To me This certainly seems to me to be the misinformation of this = thread but if you wish.... If so then a hammer made with a good felt = but is not stiff enough or to springy for the tone desired then a 5-1 = lacquer acetone solution ,or whatever, will stiffen the felt & improve = its rebound rate. On the other hand, it might be possible that on a hammer with a >bad felt quality with excessive inner friction may be stabilized to = a better >level by lacquering. >> May I submit that the Inner friction of felt has always been a = fairly esoteric & small consideration to the discussion of hammers even = though it is a know factor & frankly to me personally not very useful. Rgeards--Dale > >regards, > >Bernhard Erwins Pianos Restorations=20 4721 Parker Rd. Modesto, Ca 95357 209-577-8397 Rebuilt Steinway , Mason &Hamlin Sales www.Erwinspiano.com ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/e6/bc/8b/16/attachment.htm ---------------------- multipart/alternative attachment--
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