| Clocks Magazine tips | August 2006 |
Badly sounding bells and gongsTo me nothing is more irritating than the noise of a clock striking the hours with a badly sounding bell or gong. Many things cause this. Sometimes the fault lies with the hammer or hammers, and sometimes the bell or gong itself is the cause of the problem.It is essential that the bell or gong be fixed firmly in place on its stand and that the stand is fixed firmly to the case or movement. The case then acts as a soundboard, enhancing the sound. In the case of a bell, the hammerheads are usually made of metal in order to produce the overtones and harmonics associated with the clear ring of a bell. With a gong the opposite effect is required, and the hammerhead is usually faced with leather to damp out the strident harmonics and produce a more mellow sound. In both cases the hammer must hit the bell or gong and rebound with sufficient clearance, instantly allowing the desired harmonics to reverberate clearly. If this is not the case, the bell will sometimes produce a jangled double ring, or the gong will sound with just a muffled thud. When striking a gong, if the leather facing to the hammer is soft, it has the effect of momentarily lingering on the surface of the gong and in effect dampening out the strident harsher harmonics, thereby producing a pleasant tone. On the other hand, if over the years the leather has become hard, this has the opposite effect, allowing the more unpleasant harmonics, and overtones to sound, spoiling the tone and making the sound ‘tinny’ and harsh. In order to soften the leather, oil can be applied, or the leather ‘teased’ with a pin or very fine needle. Conversely, in order to harden the leather it can be heated with the tip of a soldering iron. Reducing the width of the leather in relation to the width of the gong will have the same effect. It is important that in order to dampen all the overtones in the gong, the leather face of the hammer must be at least as wide as the width of the gong, and the hammerhead must strike the gong squarely. This business of hardening and softening the leather and in effect hardening and softening the tone is important when trying to match the tone in a set of gongs or rods, especially if it has been found necessary to replace a particular rod in a set. The condition of the gong is another factor. Rust impairs both the sound and tone of the gong, and should be removed by buffing if possible. A gong cannot be re-blued as this affects the temper which also affects the tone. v Gongs and rods should never be bent, especially beyond their point of return otherwise the tone will be spoilt. The only serious problem usually encountered with bells is when they are damaged in some way or found to be cracked. The two edges of the crack vibrate against each other and when struck set up uneven overtones. These overtones interfere with each other and prevent the bell from ringing and reverberating as a whole. The crack in the bell can be widened with a saw cut, thereby alleviating the problem. If there is any risk of the crack opening further, a hole should be drilled just beyond the existing crack in order to prevent it travelling any further into the bell. All is not lost, even if the bell is broken in two: I once had a bell that had a clean break right down the centre. The two halves were simply glued together with Superglue; that was eight years ago and the bell still rings as good as new. Ian Beilby |
|
|
| © 1977 to 2007 Splat Publishing Ltd |
|