Torbjörn Zethelius

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  1. A Pythagorean triangle with sides 3-4-5 gives an angle of 36.87°. Maybe use that. Or try other angles by using an online triangle calculator.
  2. Kevin, your system is simple and neat but unfortunately it doesn't fit the outline of the guitar.
  3. Hi François, here's my attempt at analysis. A quick glance it seems pretty close. The bridge is at 1/5 the body length, and it's all geometry.
  4. I want to see a division between Measurement and Curves. Two violins can have the same dimensions but look totally different from each other due to different curves. When we draw a violin from scratch we must first establish the dimensions and then build the curves around these dimensions. The curves and the dimensions is like the flesh on a skeleton. It seems to me that Kevin is constructing both at the same time, and that's problematic to me. David is on the right path IMO in that he establishes the dimensions first, which is the foundation for the whole structure.
  5. François, the waist is better made using circles and tangent straight lines. I don't know how to draw on the computer yet so I can't exemplify.
  6. I have my doubts about it. It doesn't look like what I would expect from an early Strad. As Andreas said, a real life visit could clear up the doubts.
  7. The Cremonese architect Alessandro Capra published (in 1672) in at least a couple of the books that he wrote, the Cremonese Oncia (inch) which I've measured (as accurately as I could) being equal to ≈ 39.088 mm. One oncia = 12 ponti. That gives: 9 Cremonese oncie = 351.8 mm. Add 1 ponto and we have 355.05 mm. Looks familiar anyone?
  8. You forget that the modern trend of copying stems from the French makers Lupot, Pique and Aldric in the late 18th century. They were forerunners of modern violin making. The Italians very rarely copied.
  9. Stradivari probably had a sector with which he could easily work out sophisticated calculations such as the above.
  10. My statement relates rather to the Amati tradition, which was the main thought up to the end of the 18th century. Stradivari was very experimental and he came up with many new ideas during his life. So I'd like to think of him as working within the tradition, but at the same time using it as a theme to extend upon. Take the G mould for example. The relation between the C-bout and the blocks is Pi. (I just measured it to 3,1434 close enough) Given in Strad's time (before calculators, that is) it is the same as if you take a piece of string and coil it to a circle; the C bout width equals the diameter of that circle.
  11. As I see it there are two important measures; the internal measure between the upper and lower blocks, and externally the body length. The first measure relates to the (baroque) string length, and the second to the player's body size.
  12. The distance between the upper and lower blocks is the key measurement IMHO. It equals the original length of the vibrating string.
  13. Seems to be a mix of Muratov, Brooks&Degrotte (The violin and the golden number) and Hambidge (The elements of dynamic symmetry), with perhaps some original ideas. It would be nice to have an explanation of how it all hangs together.
  14. Practice makes perfect. A heavier gold chain is more steady than a lighter one. & Don't forget the ruler and shadow. It's the best.