Swinging bells can be found in church towers, in schools or also as house bells. However, the bell which has always been a means of communication is also a musical instrument. Before the right bell can be ordered, some points are to be considered:

The kind of suspension (facade, roof turret, open tower, closed tower) is important for the maximum weight of a bell or a bell formation.

The bell founder has various bell forms to chose from, to produce a bell with the wanted impact tone. In the technical terminology, the bells are compared by their ribs. The rib is the longitudinal section of the bell, in other words: its profile.

• Light rib

• Middle weight rib

• Heavy rib

• Italian rib (at Rüetschi's)

Brochures

When the approximate size of the bell is chosen, the exact tone has to be selected. Based on existing bells in the tower or in the area a tone motif is chosen, which fits in with possibly existing bells. From that the single tone of a bell results.

Bell core:

For the manufacture of a bell a tallow form has to be built. The form is produced with a stencil which has been calculated for this specific tone. First, a core has to be built up out of bricks, which is then reinforced with wire and copper nails.

Inner outline:

The former covers the core with a layer of tallow, which forms the inner outline of the bell. When the layer of tallow is thick enough and reproduces the form of the stencil exactly, a dividing layer is added. During the whole process the tallow is dried with a charcoal fire on the inside of the bell.

False Bell:

The next layer is called the "false bell" by the bell founder. The former changes the stencil and applies the second layer of tallow.

Ornaments and inscriptions:

As soon as the false bell, the so called original model, is completed, ornaments and lettering can be put on. The whole adornment is made of wax and can be sticked on the bell. The selection of the adornment and the decision, which inscriptions should be on the bell are mostly a nice piece of work for the customer.

The casing of the bell:

The casing consists of two layers. First, a fireproof layer is applied, then a supporting coat which is very gas permeable. The clay of the second layer is mixed with hemp fibers, which play an important role.

To make it transportable, the casing is armed with iron rings.

Fabrication of the crown:

The crown is fabricated parallel to the bell form. First, the former has to produce the wax crown. In a second step, the wax model is wraped in clay. The whole package is put in the oven, where the clay dries and the wax melts. The hardened clay is the negative of the form.

The form in the foundry pit:

The threeparted bell form is transported into the foundry pit. Now comes the lifting of the casing. On the inside, the decoration has graved a negative into the fire resistant layer. At this time, the inscription can still be patched. Following, the false bell is taken off and destroyed.

The hollow space for the bell-metal is created by resetting the casing on the core.

The form is nearly ready. As soon as the crown is put on, the pit can be filled with sand.

The weight of the sand prevents the casing from lifting up during the casting.

From our 10 ton furnace a canal has to be built to every foundry pit.

The alloy for swinging bells consists of 79% copper and 21% tin. The bell casting is the highlight in the fabrication of a bell. At the time of the casting, the molten mass has a temperature of approximately 1050 to 1100 °C.

The patience of the founder is strained, since it can take days or even weeks until a bell has cooled down. The founder does not know whethter the casting was successful until the bell has been unpacked and the tone has been tested.

Now comes the filigrane work of grinding. With a special grinding technique the casting skin is grind off. This work takes sure instinct and and gives the Rüetschi bells a formative characteristic.

The last piece of work is the tuning of the bell. Five tones, which arise from harmonic overtones, can be corrected relevantly. For the inspection of the frequency, we have traditional tuning forks as well as electronic frequency mesuring equipment.

Tune unity stands in direct correlation to the precision of the correction. The example shows which tones of a bell are to be corrected. Further, higher frequencies occur, but as a rule they have little influence on the mixture.

Bell a2:

• A1 - the lower octave as the base oscillation

• A2 - the prime tone as percussive tone

• H2 - as a small third to A2

• E3 - as a quint chord to A2

• A3 - as a higher octave

and multiples of these frequencies.

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