Joseph Ribes´s net vault_04 Print E-mail

Rib carving

From the montea, that is the life-size drawings of the vault, both in plan and in elevation (fig. 16), we draw and build the baibel, which is an essential tool to control the carving of the voussoirs. It is a square with two unarticulated arms, one of them cut with the curvature of the arch intrados and the other straight, facing the geometric centre of the arch (fig. 17). With the help of the baibel, we proceed to carve the voussoirs knowing for sure that their inside curvature and the inclination of their supporting beds adapt accurately to the Prinzipalbogen (Figs. 18, 19 and 20).

The Prinzipalbogen method allows to transmit and to receive all the information needed for the construction of the vault with only a single template and just one baibel, which makes the carving of exact pieces easier and allows to verify the position in space of any rib or keystone, and to extract all the information straight from the montea.

Springing-stones

For supporting the ribs and counteracting the thrusts, the vault needs the help of some solid springing-stones. The starting point of the vault is the Tas-de-charge or springing-stones. We know that in a grid crossing vault, the springing-stones must get to the point in which the arches that meet in a starting point become independent of each other. For the construction of the springing-stones we resort to the montea again (Fig. 21). On the section, we draw the horizontal plans we consider necessary and on the ground plan we draw the resulting horizontal projections in every level. With these sections we draw a series of templates (Fig. 22 and 23) that will allow to carve the pieces which form each bed; we trace the lower template on the lower plan of the ashlar chosen and, with the upper template we do the same thing on the upper side; then, we start the carving by joining one side to the other (Fig. 24).

The last springing-stone meets the arches and must be carved with the necessary inclination each of them requires, this information must be extracted from the montea again (Fig. 25). As mentioned above, in our vault, the diagonal rib is cambered with respect to the impost plan, that is, it starts at a different height than the transverse one, which adds a certain difficulty to the carving of the blocks of the springing-stones (Fig. 26). The same baibel is sufficient to also carve the curve of the cross section of the springing-stones.[....]

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