Marty Kasprzyk

Does this mean the bow hair is slipping over the string without getting the string to vibrate to produce sound? If so I suggest trying stickier rosin and/or a lighter tension d string.

Jeff Loen's book "Thickness Graduation Maps, Classic Violins, Violas, and Cellos" has many examples of the plate thickness maps of Stradivari's and other's violins that have thin and thick areas that look very similar to the static low and high stress areas that Asada's FEA maps show. On the other hand Sacconi contradicts this and said in his book 'The "Secrets,, of Stradivari': "The belly behaves like a membrane and it is well known that such a membrane, to render its best, must have a constant thickness." Who do we follow?

With unyielding determination anything different can be killed off. Non uniform stress plates give uniform tone which is good but uniform stress plates give non uniform tone which must be bad. So let's not try it.

That's a great paper--it is exactly what I was hoping to see. Thanks! Notice in figure 1 that the high deformation areas are sometimes at the areas of high stress in figure 2 while other times the high deformations are at areas of low stress like Don pointed out in his cantilever beam example. If I was making a violin I would make the low stress blue areas thinner and the high stress red areas thicker to get a more even stress pattern.

For less likelyhood of cracking and creep deformation it would be helpful to make the plate areas that have high bending stress thicker. The thick "Sacconi platforms" at the upper and lower block areas of the plates are examples. And to reduce weight and thereby increase movement and increase sound output it might be helpful to make the other plate areas that have low stress thin. A tree is a similar example in nature: The stump is thick to resist the high bending load stress from wind and the branch ends are are thin and bend easily with low stress.

Yes. The stress of making a good repair job increases with the value of the instrument.

Cracks and creep deformations are nature's way of reducing stresses in wood. Some violin people think these are important. Attached is a deformation study on DG's 'Cannone' violin. Structural_assessment_and_measurement_of.pdf

I've never seen a stress analysis done on a violin. You would think with modern finite element analysis it would have been done by now. An older method of detecting tensile strain was to apply a clear brittle varnish on the surface (https://www.stresscoat.com) which would form cracks at the high strain areas. I wonder how the VSA worksmanship judges would judge the crack patterns.

Mine's a guard dog.

In what ways does it sound bad?

The smug look came from finding another one of my math mistakes.

I use masking tape to hold the bent wood bow shape for tracing but masking tape is a fairly recent invention. I was unaware that wood craftsmen had been using strings to hold the bow's bend shape. Sometime long ago arrows were invented.

My dog ate my violin lower bout drawing.

Who was the first Cremona master who used compass contructions?