||The first step in bell making is the
mold. Brick is laid up to create a core or inside of a bell. Molding
sand is applied over the brick to finish the core.
finished core of the mold is dried with gas heaters. The core is
dried and covered with a white "parting compound" so that
the clay pattern bell, or "false" bell, may be built up
||The false bell is then finished to
the strickle-board and covered with a wax coating, which will eventually
assure a smooth casting and allow the false bell to be removed easily.
||Inscriptions, which have been made
from molding wax, are now applied. A finished false bell has the
same appearance as the bronze bell will have after casting.
||A fine slurry
of molding material is made and used to form the first coat of the
outer mold. This material must be fine enough to take all the detail
from the wax lettering and also to give a smooth finish. It must
be applied carefully, a little at a time, with drying in between.
The outer mold must reflect accurately the intricacies of the design.
case is then assembled around the built-up bell mold and as each
section is added, it is stamped full of molding sand. The material
that was previously placed around the false bell and the iron case
together form the outer part of the bell mold and are called the
its work, the false clay bell is now broken away from the core.
In casting, the space it has occupied in the molding process will
be filled with the molten bronze.
furnace is tapped, the molten bronze, at a temperature of 2000°F
begins to flow through the channels and into the mold beneath. The
Master Founder and his assistants control the flow and stand alert
to remove any slag or foreign material before they reach the mold.
With the casting completed, the Master Founder may take off his
gloves. The gasses continue to burn for hours. The cooling of the
newly cast bell is slowed and made even by being buried in the earth.
It will be left in the ground three weeks in order to assure complete
cooling. It will then be dug up and the mold broken away. Only then
will the success or failure of the casting be known. This emphasizes
the fact that the mold must be built for every bell cast from a
33 ton giant to the smallest carillon bell of perhaps 6 lbs. weight.
is then closed down. The halves must be fastened together very securely,
so that the molten bronze cannot escape where they are joined. This
mold has now been buried in the earth in front of the great, wood-fired
furnace. Channels lined with refractory material have been made
to carry the molten bronze directly from the tap to the mold-head.
smaller bells, the bronze may be melted in a tilting crucible gas
furnace. This also facilitates the increase in tin content, which
is used in smaller bells of carillons, in order to achieve a clear,
brilliant tone quality. The tin content is raised to nearly 25%
in the smallest bells.
tuning, the bell is brought to a high smooth bright finish by means
of cleaning and burnishing bronze bells.
||All bronze bells by Carillon
Technology are tuned to high standards. Larger bells must be tuned
on a vertical boring mill. Bells are cast slightly thicker than
required, that is, with all the partial tones higher in pitch than
their correct positions in the scale. By a careful process of removing
just the right amount of metal at different levels inside the bell,
the partials are then lowered to the correct positions.
strategy must be laid out for each bell as it comes to the tuning
room from the foundry whereby it will be possible to bring all partials
to the correct pitches at the same time. Very few partials can be
raised in pitch at all, and those only very slightly.
such as the upper bells of carillons, and the bells of chronochimes
may be turned on an engine lathe. All bells must go through the
same exacting process, which is now controlled with the greatest
accuracy by means of electronic pitch measuring instruments, reading
to 1/100th of a semitone.
the process of creating a uniquely finished bell.
Other trademarks and tradenames used in this document refer to
either the entities claiming the marks and names or their products.Carillon
Technology disclaims proprietary interest in the marks and names