Re: Re: Vanduzen & Tift 16″ x 22″ dia bronze bell
Photos of the casting of bells at modern foundries are available from several of the bellfoundry Websites. (One starting point is http://www.gcna.org/data/IXfoundriesCtry.html.) You can also find information about casting materials at some of them.
“Template” is correct. They come in pairs – one for the inside profile of the bell and one for the outside – and are often called “strickle boards” or simply strickles. They are used to make sure that the bell is rotationally symmetrical and of uniform thickness. The outside strickle is usually visibly notched to produce the bead lines (or moulding wires) which are the simplest form of exterior decoration. Some bellfounders also added very tiny notches at regular intervals to produce alignment markings for the addition of lettering to the mold, for the maker’s standard inscription and for any custom inscription that might be ordered.
Reusable molds for a bell shape do not permit bead lines or the application of lettering. That is why almost all cast steel bells (e.g., farm bells) are totally blank. (Occasionally you will see one with a size number or similar marking on the top of the shoulder or on top of the sound bow. Those don’t interfere with the separation of mold and bell.)
The lost wax process was used in medieval times with actual wax, when a bell mold was essentially a single piece. Most bellfounders sooner or later switched to a similar process using a false bell made of other materials and constructing a two-part mold; after it was baked, the parts were separated, destroying the false bell; the parts were rejoined for casting of the actual bell. Most modern bellfounders have taken the process one step further, making the inner and outer parts of the bell mold separately, so that no false bell of any kind ever exists. But even at the height of demand for bronze bells, a century ago, there was not enough demand for specific sizes to make reusable molds worthwhile. Sand casting techniques have been used by some modern carillon builders for small bells (10 to 100 lbs, roughly), but the older techniques remain the best for large bells.
Old American bells can be tuned, though there is no reason to do so except in the case of a chime (several bells together, for playing tunes). When they are, they will look like modern bells on the inside, with distinct bands of coarse marks where the machining was done. That is unmistakably different from the faint markings left over from forming a mold.