|| Bells’ repair
New bell loft's buying is one of the happiest events in every orthodox temple's life. The temple inherits the voice, unique, inimitable, and peculiar only for it. It’s not so important, what weight the bells would have, whether they would be large or small – the happiness won’t lessen.
But bells are a very fragile thing, and they acquire careful usage. Unfortunately, sometimes bells (even new) break. In this case you shouldn’t fall into panic, and hurry to pass the bell to the meltback all the more. They would give only 2$ per kg, and may be less. The most intelligent way to solve the problem is to repair the bell. If the restoration is made in time, and the defect (split) hasn’t reached critical size, the bell would sound well after being repaired and would serve for many years. Surely, the bell's repair should be made qualifiedly, if not - you may gain the opportunity to loose the bell finally.
The repair-defectologic group of Moscow Bell Centre has repaired dozens of bells. Our specialists start bell's repair with defectologic bell's inspection; according to its results bell's reparability is determined and the reparative method is chosen. For our work we use the equipment which is applied in industry: ultrasound devices, x-ray examination, penetrating paints (penetrants).
Taking to consideration the specifics of bronze bells, we have worked out the method to diagnose the articles of any size both at the place of their hanging and in stationary conditions. This method of non-destructive control was checked on many bells and includes four stages of work: visual inspection, capillary defectoscopy, ultrasound and x-ray defectoscopy.
Visual inspection is usually held after bell’s clearing from mud. As a rule the bell is inspected in the following zones : verberation’s ring, the middle part of the skirt, shoulder, pan (bottom), ears. The investigation is held both internally and externally, with preferable usage of illumination and glass with magnifying power 5-7 times. Suspicious places are cleared to metal shining, as the splits and other defects are better seen against yellow bronze’s background. The places where the defects have been determined become the mostly controlled objects during the following stages.
The practice has shown that it’s very hard to determine real places of splits’ endings and their branches even with glass. Capillary defectoscopy helps to solve this problem successfully. This method’s core is in the following: a special dye, often red-coloured, which easily penetrates to the smallest splits, is put to the inspected part of bell’s surface. In some minutes after its putting, the dye is cleaned and the so-called revealing reagent (a formula, which possesses a high absorbing ability, and can draft the dye, which has penetrated to the splits, onto the surface) is put to its place. As a result we receive the split’s clear image, which allows to determine it’s geometric characteristics - form, size, etc. - with a high exactness .
To determine the defects, which don’t face the surface (such as flux inclusions, abscesses, internal splits and so on), the methods of ultrasound control and x-ray examination are used. These methods require special equipment and allow to determine defect’s size and location rather exactly.
One of the most important problems in our work is to find the defect, which has an industrial or exploitation reason, as quickly as we can. For the first case it’s necessary to hold careful bells' inspection when you purchase them, to find hidden factory defects. This will allow to lessen the possibility of break significantly. As a rule, it’s impossible to determine production defects visually, that’s why we usually recommend temples to hold ultrasound defectoscopy at least for middle and large bells (5-8 poods and more) before their receiving. This will help to solve all the mistakes with the producer or the bells’ seller in future.
As for the exploitation defects, these are the splits, which have a tendency to grow, as a rule. This means that if you ring a bell with a split, the split will grow gradually and will make the bell unfit for repairing and future using. That’s why it’s important to find the split and repair the bell in time.
The first sign of the defect's apparition is the decrease of bell sound's time; its tone’s changing, drumming noise, unpleasant sounds and so on. Only the bell-ringer who works at the bell-loft constantly, can notice them. Nowadays the Bell Centre processes bells’ certification, which concerns the determination of bell’s fall time and its frequency behaviour according to the cassette record of bell’s sounding with the help of computer. Making regular records and sounding’s decryption, you can determine bell’s condition correctly. If something changes, you can make an inspection in time and repair the bell, if it’s necessary.
Unfortunately, the practice shows that usually when people ask for help from us, bell’s defects reach a significant development degree. This fact considerably decreases the possibility to make restoration successfully. Nowadays there are three methods to repair the bells: welding, brazing and splits’ widening (cutting). All these methods to remove the tension and to forestall the following splits’ growth require to make holes (usually 5-10 mm in diameter), coming exactly through splits' endings, even its smallest branches, taking both external and internal endings to consideration. Some bell-ringers don’t know it and try to make the simplest repair of their bells by guess-work themselves, making holes and following splits’ cutting. But such repair often turns to sorrowful results - the bell gets out of order in a small period of time. We were repeatedly assured that the more valuable the bell is, the harder the defect is – the more qualified the approach for repair should be.
But surely it’s better to take prophylactic measures and not to let the bell break, then fight with the consequences in future. The following methods of bells’ prophylactics have shown themselves as the most effective ones:
Bell’s clapper should be produced from soft iron and should consist maximally 1/10 (for small and middle bells) and 1/25 (for large bells) from bell’s weight. We don’t recommend using very light clappers, as in this case the sounding becomes worse.
The clapper shouldn’t hang freely; it should be attached to a bell with a string, the distance between it and bell’s border should be similar to palm’s width. It’s better to decrease this distance in hard frosts. You’d better not ring old bells in this case at all, as the bronze becomes very fragile when frosts come.
You shouldn’t allow unknown people (who don’t have professional abilities) to ring bells;
You’d better take acoustic characteristics of all the bell loft’s bells and make repeated measures (once in 5 years) to compare them with the etalon, as it’s hard to notice the changes in bell’s sounding at the starting point of split's growth, they can be distinguished only when the split has reached significant sizes.