Thanks for you're thoughtful response. ----- Original Message ----- From: "Overs Pianos" <sec@overspianos.com.au> To: "Pianotech" <pianotech@ptg.org> Sent: Saturday, August 13, 2005 7:56 PM Subject: Re: string termination > Hi Carl, > >>A lot of things about string terminations have bugged me for some time. > > Me too. This is a topic which raises the level of pianotech list interest Finally! >>Ron Overs promotes hardening of the capo bar, yet the agraffe is a >>relatively soft material (brass). The difference is that the capo is >>straight and the agraffe is round. Wouldn't the agraffe last longer if it >>were heavily plated with chrome, nickel or?? > > It would last longer if it was plated with a hard or harden-able material. > I think brass is a very poor material for string terminations. After > re-profiling (both new and used agraffes) we have been plating them with > Electroless Nickel for some years (since about 1996). This plating is > harden-able, and it plates with a uniform thickness in the string holes. > Normal electoplating won't result in a uniform build-up of plating in the > holes, which is why Chrome isn't a viable alternative plating material. > Electroless Nickel plating is a process which, once started, is a purely > chemical plating process. This is why it results in a useful build of > plating in the holes. That's interesting. I'm familiar (a little) with electroless plating but I didn't know it was hardenable. Can it be hardened over aluminum as well as brass or other metals? I assume a plating shop would have the details. > For the most recently remanufactured piano we built, I decided to try just > shaping the brass agraffe holes without plating and hardening. The results > were very disappointing. The best results we have had to date are when the > agraffes are Electonickel plated. We've been getting them plated with a > thickness of 0.05 mm (2 thou). The next set we do will be plated with 0.75 > mm to increase the strength of the plated surface. I have been suspicious > that the plating is on occasion collapsing and flaking off, due to > collapse of the soft brass substrate. > >>Now under normal circumstances, the piano string is terminated (pivoted) >>on the top surface of the agraffe. Let's call that North. Let's call the >>bottom of the agraffe South. The other two surfaces would be called east >>and west. >> >>At the bridge, the string is terminated at maybe SSE (south south east). >> >>Wapin claims that their vertical bridge pin encourages the string to >>vibrate in the horizontal direction quicker before the energy has been >>dissipated in the vertical mode and hence -longer sustain. >> >>Let's make it a given that the impact of the hammer is in a northern >>direction. >> >>Stuart of Australia claims that their bridge termination increases the >>vertical vibration of the string. Hmmmm? How does that effect the >>sustain???? > > I've watched struck strings on the Stuart piano, and my observations are > that the strings in his instruments behave like any other standard string > termination. I have no reason to suspect the Wapin termination will be any > different either. > >>My esteemed colleuge from one of the fly over states suggests that a >>string starts out vibrating vertically, slowly starts to drift >>horizontally but never gets to true horizontal. He also suggests that a >>string tends to vibrate at 90 degrees of its termination. I want to find >>out if that is true. > > The string certainly starts out vibrating in the vertical plane, then > changes to an elliptical vibrating mode. It appears to degenerate into an > essentially circular mode at the final decay stage. > >>I don't really know, but it has been my assumption (maybe in error) that >>the string vibrated vertically, slowly drifts elliptically, approaches >>horizontal, then elliptically in the other direction and then returns to >>vertical at a much lower level. This would then be a cyclical phenomenon. >>Sorry for the flurry of five dollar words. >> >>I've been thinking of a new bridge termination scheme for rebuilding but >>I'm not going to proceed till I answer a basic question. > > I suspect that you are about to join a few others, who are on this > Darwinian quest. > >>Here's my question: A vibrating string has two terminations. It is >>excited in the northern direction. (Ignore the strike point) What effect >>on tone will be the termination of the two ends of the string????? Both >>north, one north and the other south, east or west???? Or no big >>difference?? >> >>I have recently found plans on the net to build an led stroboscope. I will >>build this and look at a string under vibration. I could stretch a wire >>across my garage and look at it with different terminations. >> >>If some of you deep thinkers have an answer to my question that makes >>common sense, I won't have to do this. Give me your feedback. > > It is a worthy field of investigation Carl. Conventional bridge pins > suffer severe damage at the termination point. An intermediate solution > would be hardened bridge pins, but it will be a costly exercise. As does the wood and that's why I am interested in this. Carl Meyer PTG assoc Santa Clara, Ca. > Ron O. > -- > OVERS PIANOS - SYDNEY > Grand Piano Manufacturers > _______________________ > > Web http://overspianos.com.au > mailto:ron@overspianos.com.au > _______________________ > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives >
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