David Love wrote: > What do you notice happens on these boards with the softer more > resilient hammer when you try and get a very big forte? David, The use of the word "resilient" is confusing here. Resiliency is the measure of a material's ability to recover its shape after being deformed. The coefficient of resiliency (also known as the coefficient of restitution) is measured in several ways. The classic method is to form the test samples into spheres and drop them form a height onto a massive surface like an anvil. How far the ball bounces back up determines its resiliency. If it bounces back 90% the Coefficient is .90 for example. Resiliency is one of the factors that determines what happens when bodies collide. A body with low resilience can not transfer much of its kinetic energy since most of it will be absorbed. A body with higher resiliency can transfer more of its energy since less will be absorbed. It is bit more complicated than this but this is a major factor in what happens when the hammer strikes the strings. I notice that most people use the word resilience completely opposite from its true meaning. Most technicians think that soft felt is more resilient that denser felt. What they are really talking about is compliance. Felt is a fairly compliant material but is not particularly resilient. If you were to compare the resiliency of soft felt to that of more dense hard felt made with the same fibers you will find that the harder felt is more resilient. Off hand I would have to say that one of the reasons felt is used to make piano hammers is because its resiliency can be so easily controlled by making it denser or less dense. The whole process of wrapping the felt over the molding produces a hammer that is denser on the inside and less dense on the outside. The less resilient upper surface of the hammer will damp out more of the upper partials and absorb more of the energy of the impact while the inner cores higher resiliency will be more efficient and bring forth more overtones. A lot of technicians are shock to here that lacquer increases the hammer's resiliency. That's why it sounds brighter and louder. John Hartman X-PTG John Hartman Pianos [link redacted at request of site owner - Jul 25, 2015] Rebuilding Steinway and Mason & Hamlin Grand Pianos Since 1979
This PTG archive page provided courtesy of Moy Piano Service, LLC