Quality Applications

Faro Technologies Inc.'s FaroArm Benefits Accuracy to ±0.001 in. Captures unlimited number of data points CAM2 software creates CAD file from data. www.faro.com

Digital-Age Tool Helps Create Classical Sculptures
Faro Technologies Inc.'s FaroArm

For more than 2,000 years, marble from the flanks of Mount Altissimo and other nearby mountains in the Apuan Alps of Tuscany, Italy, has been quarried because of its unique properties. When chiseled and polished, the stone captures light and reflects back eggshell and vanilla-colored shades. For this reason, sculptors (including Cellini, Bernini, Michelangelo and Donatello) have been using the marble for centuries.

 The process of sculpting relies on a partnership between artist and sculptor. Artists turn their visions into plaster models known as maquettes and then send them to their studio partner. Studio artisans tack small studs into the maquettes at points that roughly define the object's shape. Using calipers, rulers and large sheets of paper, the artisans take measurements from these points and scale up the model to the size envisioned by the artist.

 However, using mechanical implements during the transfer of concept from maquette to finished piece can lead to problems with both the proportion and detail of a sculpture; measurements shifted just a fraction of an inch can alter the appearance of the object. The difficulty lies with the limited number of measurements that an artisan can take using mechanical tools.

 To eliminate confusion and improve fidelity between maquette and finished sculpture, the marble studio di Stagetti Nicola of Pietrasanta, Italy, replaced the classical model scaling technique with a FARO Technologies 3-D digital measuring arm, which gives the studio the capability to capture an unlimited number of data points from a maquette. The FaroArm is a portable coordinate measuring machine that uses optical encoders as the "joints" to track the exact position of its attached probe. It's similar to ones used in aircraft and automotive production to check the accuracy of machined and assembled parts, and to translate dimensions of clay models into metal shapes.

 Using the instrument, di Stagetti artisans trace the shape of a maquette as a sequence of discrete points or as a continuous line of points. These data are transferred to a computer, where the image of the maquette is recreated as a CAD file. Then, using the computer to scale up the dimensions, the studio sculptor begins the task of removing marble and finding the image that the artist envisioned within the stone. Details of points, lines and curves can be matched to the model to an accuracy as fine as ±0.001 in.

 By touching the arm stylus to various points on the emerging statue, artisans can check their work against the CAD image. FaroArm's companion software, CAM2 Measure, compares the new point that the artisan has taken with the original developed from the maquette and shows specifically how much more material remains to be chiseled.

 In service for more than seven years, the FaroArm has held up under dusty studio conditions consisting of gritty marble powder created by high-speed chisels, say the artisans at the di Stagetti studio. The studio uses the arm to turn out an array of pieces, from pilasters and capitals for columns to garden fountains, as well as statues and relieved pieces from contemporary artists and replicas of ancient works.