Violin Forum/Message Board

[actonern]

Sacconi (and others) typically provide a schematic drawing of recommended plate thickness for top and back of violin/viola/cello plates.

My question has to do with the proper transition zone between these thicknesses.

I am currently working on a cello, so am focussed to those thicknesses at the moment. The centre "circle" of the back plate is 7mm, then 6 mm then 5, 4 and so on.

What exactly do these "circles" mean? Does the centre 7 mm circle mean that the entire area is 7 mm or does it mean that there is a gradual increase from 6 mm to a smaller area where it finally reaches 7 mm?

Am I being at all clear? It makes a big difference in the final outcome of plate thickness and resistance how one interprets this information. Clearly the jump from 4 to 5 to 6 to 7 mm does not occur in jagged jumps. I guess I'm asking if the transition occurs after the line or before it?

Best regards,

[Michael Darnton]

The usual interpretation is that the graduations change gradually, and those lines mark the spot where the graduation passes through that thickness, or, in the case of large areas, the thickness of the area, considering it will have to blend into something else. I wouldn't get too carried away with defining things too carefully, as long as you do the same thing everywhere. The balance of the thicknesses is more important than the actual numbers (i.e., the location of the thickest spot is more important than its precise thickness).

In general, changes should happen gradually, not suddenly. For instance, the growth from 2.5 in central areas of violin bouts should slowly blend to the 3.0mm around purfling, not showing a step.

[actonern]

"...those lines mark the spot where the graduation passes through that thickness..."

Thanks for the reply Michael.

Does that mean that if the "7mm" line marks the place where the graduation "passes through that thickness" that the centre area of the circle is something more than 7 mm?

Best regards,

[Jack H.]

the center would be 7 to the inside line, from there a smooth transition to 6 being the next line... etc.

Halfway between the two lines would be 6.5

easy peasy.
now for the hard part, getting it nice and smooth and even.
Just had a whole summer full of regraduation work.

nothing like repetition to hone the skills.

[John Cadd]

Sacconi reminds you that the violin plates can vary in thickness depending on the texture of the wood but they all end up with a tap note of F front and back. It`s in the book but scattered around too much. The whole book needs a proper index to find stuff.Make your own on the spare sheets at the back.

[MANFIO]

In a recent thread on MAESTRONET Bruce Carlson mentioned that in many backs of Cremonese instruments there is a "plateau of the thicker central area and how it is clearly not concave like the rest of the inside longitudinal line."


You can see a CT Sacn of an Amati violin showing that on Post # 33, by Bruce Carlson, here:

http://www.maestronet.com/forum/index.php?showtopic=322374&st=20
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