estebanana -> RE: Saddle vs Bridge (Apr. 28 2015 1:51:57)
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quote:
It's been said many times that a dip in front of the bridge (towards the hole) is nothing to worry about. I've noticed that guitars that have that dip are also slightly concave in that are, as opposed to being convex near the hole... ...which means that the bridge must be a bit concave too on the area where the saddle sits, right? The answer is _No_, the bridge saddle mound or slot area is not concave. Not on a healthy guitar. If the bridge has been defected to the point where the saddle slot mound is also deflecting, this is not normal and there is a problem. A bridge should not be pushed into a state of deflection so far that it actually distorts the saddle slot. This is very important. If that is happening a guitar will probably still play, but ideally the saddle mound and saddle do not deflect. Since no one else wants to be clear about this, here goes: The original question was based on two main assumptions which are probably false. The first assumption was that the bridge bends into a distortion, as the top is pushed down by the force of the string bearing down on the saddle, that is radical enough to bend the saddle. The second was that the saddle is being held in a state of distortion to conform to the saddle slot. A better question would be : "Is is normal for the bridge to be pushed into a concave condition?" And why or why not? Why does a bridge flex to the point of allowing the saddle mound to distort? _____________________ The bridge may or may not be held in a state of deflection depending on the local and total systemic flexibility on that particular bridge. Individual bridge flexibility coupled with other factors such as: 1. Top flexibility across the grain. Strength along the grain between bridge and sound hole, and long grain strength between tail and bridge. 2. Degree to which a contra puente or bridge patch is stiffening the cross grain flexibility of the top under the bridge (You've been wondering all these years what that bridge patch is for in addition to adding cross grain stiffness out side the wings of the bridge, no? ) A bridge patch can shore up the cross grain stiffness under the bridge enough to prevent the bridge from deflecting too much under tension, although that varies from guitar to guitar, and again is subject to all the complex parts of the bridge top system. 3. Force of the strings on that particular guitar which push down and deflect the top. Big subject. There are many factors at play at the same time when it comes to the complex mechanics of the bridge top connection vis a vis the force of tension on the top. To make assumptions based on partial knowledge of how this system works is confusing and only adds to the greater elaboration of misconceptions about guitar making. The trouble begins when someone makes a blanket statement like this in which it is assumed the bridge is always bent into a pretzel. Some of you guys know quite a bit about guitars, but if you insist on defending assumptions you make based on not having actual shop experience please support out the assumptions with some empirical evidence. Take measurements, record data, or otherwise support your claims. But please don't countermand those who spend all their time working in the shop on these problems. ____________________ The real question to ask is: Does the tension of the strings "clamp" the saddle into the slot with enough force to create a compression fit which enables the bridge and saddle to move as one unit? That question touches off other questions....The issue is that does this really matter on a flamenco guitar? Will a deep investigation of the physics really reveal anything we don't already practice as a result of a hundred years of learning by trial and error? Asking questions is great, but if you base a question on a false claim that guitar makers deal with in daily building practice of making then be prepared for a logical refutation of an incorrect assumption. The reason guitar makers have common sense about building is because their teachers shattered the foggy thinking of making assumptions and encouraged hands on practice. That is experience that should be respected and a guitar maker should not have to apologize for taking someone to school on that if they keep pushing false assumptions.
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