Three-circle method
The three-circle method , also called circle dotting , is a historically outdated technique of stone sculptors that is still used today , which enables the production of models or originals in any enlargement or reduction. Of Balthasar Neumann (1687-1753) is known to the calculations of its rococo a special proportional angle, the instrumentum architecturae used.
The three-circle method is based on the stereometric law , which states that from any three fixed points in space a fourth point can be determined by distance measurements.
The largest sculpture made from natural stone using the three-circle method is the continuity of Max Bill in front of the main building of Deutsche Bank in Frankfurt am Main . It was transferred four times enlarged from a plaster model.
Procedure
The main points are set up on the model, from which the required dimensions can be transferred with calipers or callipers . The main points are transferred to the sculpture to be produced in the desired scale and, depending on the required number of main points, result in imaginary connecting lines of several triangles. The main points are of great importance for the stone sculptor and must be applied very precisely to the sculpture, otherwise deviations in the creation of further detail measuring points will multiply.
With an integer transmission z. B. 1: 2 or 1: 3, the transmission can be picked up on a metal strip that is mounted on a wooden rod. The dimensions result, for example, from a magnification of 1: 2 by doubling the compass size or turning the compass twice on the measuring strip.
When transmitting on a non-integer scale, for example 1: 1.7, so-called proportional angles are used, which represent a fixed triangle as a measuring instrument. The dimension of the model is plotted on one leg of the angle and when this dimension is transferred to the other leg of the proportional angle, the desired dimension for the sculpture is measured from the intersection of the legs.
execution
Before the main points are attached to the rough stone, it must be sharpened to the rough outline shape . The main points are to be laid out in such a way that all necessary detail points can be reached and they are attached to the model and the sculpture with rivets with special glue. The compasses are used for measuring in the recess of the rivets. Furthermore, depending on the size of the sculpture, the stone sculptor needs several plungers and callipers. At least three compasses and three fixed main points are required to transfer a dimension to the sculpture.
However, depending on the requirements and assessment of the stone sculptor, more than three main points are attached. This creates a corresponding number of triangles according to the main points created, insofar as they are necessary for the stone sculptor to produce the sculpture. The more experienced the sculptor, the fewer main and detailed points he needs to create the sculpture. The size of the compasses depends on the sculpture, for example adjustable wooden callipers were made during the production of the sculpture "Continuity", which had to be stopped to measure in front of three stone sculptors. Due to the size of the sculpture, the Italian stone sculptors in Carrara also used wooden compasses with two adjustable arms at the ends of a wooden slat to measure the dimensions.
In order to determine a certain point in three-dimensional space on the sculpture, three adjustable compasses are used, hence the name of this sculptural method. The adjustable compasses must be fixed after a dimension has been determined. First of all, so-called two “cross dimensions” are required, which are measured by creating two compasses from two different main points on the respective scale and marked at their intersection. The missing depth measurement occurs when the third circle meets the intersection of the cross measurement. With the three-circle method , it is gradually possible to cover the entire shape of the sculpture with measuring points that allow the sculptor to transfer the figure as precisely as possible. A network of points is created on the model and on the sculpture, which surrounds the shape. Stone sculptors mark the compasses with different colors depending on their use for the cross dimensions and for the depth dimensions so that they cannot be confused.
The application of this method requires a great deal of experience from the stone sculptors and an excellent spatial sense. With the three-circle method , it is also possible to transfer templates mirror-inverted.
literature
- Jaromir Remes: Reproduction Techniques of the Stone Carvers. P. 71 ff. In: Training center for the stonemasonry and sculpture trade (ed.): Steinmetzpraxis. The manual for daily work with natural stone , 2nd revised edition, Ebner Verlag, Ulm 1994. ISBN 3-87188-138-4
Individual evidence
- ↑ Remes: Reproductive Process. P. 76 (see literature)
- ↑ Werner Spieß: Continuity. Granite monolith by Max Bill. Illustrations on pp. 78–81. Deutsche Bank (Ed.), Busche Verlag, Dortmund 1986. ISBN 3-925086-01-3
- ↑ Remes: Reproductionstechnik , p. 77 (see literature)