Computed tomography used to recreate a Stradivarius violin
By Jan Belezina
December 4, 2011
Almost three centuries after Antonio Stradivari's death he remains the greatest luthier of all times, with roughly 650 out of 1000 violins of his making still testifying to his exquisite craftsmanship. As many of the surviving instruments adorn museums and private collections, playing a Stradivarius violin is a privilege reserved for few and envied by many. But this may soon change thanks to a radiologist and two violin makers who decided to harness computed tomography (CT) imaging and special manufacturing techniques to create a reproduction of a 1704 Stradivarius violin.
Dr. Steven Sirr, a radiologist at FirstLight Medical Systems in Mora, Minnesota, and professional violin makers, John Waddle and Steve Rossow, decided to recreate the instrument known as "Betts" with an unprecedented level of accuracy. Their goal was to gain a better understanding of what makes Stradivari's work superior and then use this knowledge to provide young violinists around the world with affordable replicas.
First, Betts was snatched from the U.S. Library of Congress and scanned with a 64-detector CT to create over 1000 CT images. These images, converted into stereolithographic files, were then fed into a CNC router, custom made by Rossow. The machine carved the scroll and the front and back plates of the violin from different woods. Then Rossow and Waddle finished the pieces, put them together and varnished the instrument.
"CT scanning offers a unique method of noninvasively imaging a historical object," said Dr. Sirr. "Combined with computer-aided machinery, it also offers us the opportunity to create a reproduction with a high degree of accuracy." This is achieved by measuring not only size and shape, but also wood density and the fluctuations of thickness and volume. This means the technique can be used to identify precious instruments and even establish their unique repair history on the basis of evidence such as cracks and worm holes. Such information may be extremely valuable since Stradivari's violins tend to cost a fortune.
That's a whole lot of ramifications for a project born out of curiosity. Dr. Sirr, himself an amateur violinist, first scanned an instrument in late 1980's. "I assumed the instrument was merely a wooden shell surrounding air," he said. "I was totally wrong. There was a lot of anatomy inside the violin." See this video to find out for yourselves what he found inside Betts.