CT scan used to recreate legendary Stradivarius violin replicas

Antonio Stradivari's violins are considered the greatest ever made. Rare not only because just 650 out of 1,000 of his violins remain, but also because the tone they emit has never been replicated in other violins. New computer tomography has been used to harmlessly probe an existing Stradivarius to unlock its secrets and replicate it.

Given the hours spent in line waiting to be x-rayed at the airport, it's amazing no one has thought of it before.

Fortunately Dr. Steven Sirr a radiologist from Minnesota and professional violin-makers, John Waddle and Steve Rossow did. They wanted to understand why the Stradivarius delivers such a unique sound, and then create affordable replicas for a new generation.

Existing violins are so rare most are in private or museum collections. Dr. Sirr managed to source a 1704 Stradivarius known as "Betts" from the Library of Congress; he then non-invasively scanned the Betts with a 64-detector CT to create over 1,000 CT images.

The images were converted into stereolithic files; a process for the creation of 3D models to build prototypes. In this case instead of building up a model, the files were fed into a CNC router that cuts things down into precise shapes. In fact this router was custom made by Rossow for crafting violins.

The router made the front and back plates and the scrollwork from different woods. Rossow and Waddle then finished the pieces, fitted them together and varnished it, creating a nearly identical replica.

The CT scans were not only able to recreate the shape to a high level of accuracy, but also measure the wood density and fluctuations of thickness and volume — all things that would contribute to the unique sound.

In June, 2011 the team created another replica of the Betts at a violin maker's workshop at Oberlin College in Ohio. Together with a class the trio created a copy sans varnish, that when played was reported to have clear precise tones. While purists may argue the copies are just not the same as the real deal, the process does have practical applications.

The CT's don't just replicate rare or historical instruments; they also create a virtual roadmap for repairing them. Once scanned the CT images can show minute cracks, worm holes and features of each piece that makes them unique and valuable.

Dr. Sirr, an amateur violinist in his own right summed it up in a remarkable synergy between his job and his hobby, "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."

There is even a video that shows just what IS inside the Betts Stradivarius.

Gizmag, via Tecca

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