A pointing machine is a measuring tool used by stone sculptors and woodcarvers to accurately copy plaster, clay or wax sculpture models into wood or stone. The device is a contraption of brass or stainless steel rods and joints, which can be placed into any position and then tightened. It is not actually a machine; its name is derived from the Italian macchinetta di punta. This tool was first invented by the French sculptor and medallist Nicolas-Marie Gatteaux (1751–1832)[1][2] and "perfected" by Canova.[3]
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The pointing machine is used for making one-to-one copies of existing sculptures and to execute models from plaster, modeling clay or modeling wax in materials like stone or wood, on the same scale. Enlarged or reduced scale sculptures are not possible via this method (for this a set of calipers or a three-dimensional version of the pantograph was used).[4]
To better control the end result of the finished sculpture, sculptors have increasingly taken to making a detailed model, and then reproducing this on the same scale or enlarged this in stone. Especially in the 19th century, sculptors would work along very specific methods: first a wax or clay model was made, of which a plaster cast was taken, which in its turn served as the model to be copied in stone, with the use of calipers or a pointing machine.[5] This is called the indirect method of carving.
The advantages of this method are that the end result is very controllable and that the chance of making irreparable mistakes is reduced drastically. In addition, the process is much faster when carving difficult sculptures, because the search for the right shape is done during the modelling process instead of during the carving itself, thus making it much easier to adjust it or make changes. Finally, using this method, much of the work or all of it can be done by assistant sculptors, increasing the productivity. The disadvantage of using the pointing machine is a great loss of directness and the chance of loss of expression.
Gradually, famous sculptors would more and more tend to use assistants. Sometimes a sculptor would run a large workshop with dozens of assistants and pupils. Art academies were formed where the skills of sculpture were taught in detail. The consequence of this development was the generation of a kind of 'academy art', from which some sculptors wanted to distance themselves. Sculptors eventually returned to more direct forms of expression, by means of for example the 'direct carving method', impressionism and expressionism, sometimes influenced by the indigenous art of Africa and Oceania, that brought about a shock because of its directness and raw expression. Because of this, the pointing machine was used less and less, also because the knowledge and the skills of carving in wood and stone were rapidly getting lost during the 20th century.
To transfer measuring points from a model to a block of stone or wood, the sculptor usually takes three reference points on both model and block, from which to start. By using three of these points, a sculpture can be measured accurately, for the three directions of measuring are hereby defined (width, height and depth). These three measuring points are traditionally used by sculptors to copy a sculpture with calipers, but this is was simplified significantly with the invention of the pointing machine.
On these basic points, a (usually wooden) T-shaped support is mounted, the cross. On this crosswood, the actual pointing device is attached. By then moving the arms of the tool in such a way that the point of the needle just touches the point to be measured on the model, for instance the nose of a bust, the sculptor sets the device. Next he takes the whole cross, pointing machine and all, to the block of stone or wood and hooks it up in the identical, corresponding basic points. The needle that defines the measuring point can slide. By subsequently carving or drilling carefully until the needle touches the stop, the sculptor can place his measuring point exactly in the block. By thus copying several dozens or hundreds of points, an accurate copy can be carved. The end result however will still depend on the skill of the sculptor, because these points are only the basis.
The real advantage is the need to measure each point only once, instead of three times with callipers (height, width and depth). Also there is no need to read scales in inches or centimetres, and consequently much less room for error.
Usually, the sculptor will make his own crosswood for the statue, as a small statue obviously will need a much smaller one than a life-size one.
Before the invention of the pointing machine by Gatteaux, sculptors used several methods to measure and copy sculpture, such as grids, which were already in use in early Egyptian sculpture, measuring sticks and calipers. The main technique was to measure the model from three fixed points with calipers.
Nowadays pointing machines are available in laser versions as well. These have the advantage that the needle is not hindering the carving, and that the sculptor hears an audio-signal to warn him when the right depth is reached.
The latest developments are computer guided router systems that scan[6] a model and can produce it in a variety of materials and in any desired size.[7]
Cami Santamera: Sculpture In Stone, Barrons Educational Series Inc, 2001/10/01, ISBN 0764154249