Violin Forum/Message Board

[Chris Knowlton]

In the Sacconi book there is a contour diagram of a typical Stradivarius front plate. The contour lines in the upper and lower bouts are close to being concentric (For the sake of discussion lets use the area below the widest point on the lower bout).
This seems to imply that the arching in that area, from the edge of the plate to roughly 30 to 35mm in from the edge, should be the same or very similar.

I understand that poster arching drawings represent the result of years of string tension, and it is my understanding that the long arch drawings on Strad posters (in this case the Milanollo poster) are more “suspect” than the corrected cross-arching drawings.

Does it then follow that the arching (from the plate edge through the first 30-35mm from the edge) at the centerline of the plate should look more like the lower bout cross-arch template than the long arch template? (The long arch on the poster becomes convex sooner, (closer to the edge)).
_________________
I make sawdust mostly

[Michael Darnton]

OK, I'm going to try.....

First, don't take anything that Sacconi says about violin specifics as literal truth. His great contribution wasn't in the details, it was in presenting a way to look at the details. If you were to distill 70 years of American politics into one checklist, how much validity would it have to predict Bush's next move? None, right?

Averaging greatly changing and variable data over a long range doesn't really have any validity, and that's what Sacconi does a lot of.

That said, no, it doesn't follow. ("Does it then follow that the arching (from the edge to the first 30-35mm from the edge) at the centerline of the plate should look more like the lower bout cross-arch template than the long arch template?")

If I wasn't on my third glass of wine, I could probably see more deeply into this problem.:-)

Sacconi's contour lines, though I sympathize with the idea, aren't really a good way to deal with the issues here. They're too crude for what's going on. Maybe if there were more of them, we could use them to get a handle on things, but there aren't, and we can't.

But keep asking questions......

[Chris Knowlton]

Hello Michael. I corrected my long arch template per your response to my earlier thread “Milanollo arching dilemma”. It worked well and fixed most (perhaps all) of my arching issues.
The plate currently matches the corrected long arch template. When I draw contour lines they flow smoothly, look consistent, and are balanced, but they move closer to the edge and to each other as they approach the centerline from the lower bout cross-arch (same at the upper bout). Perhaps this is typical or at least correct for the Milanollo but it was far enough from the Sacconi drawing to cause me to question the difference.
_________________
I make sawdust mostly

[Michael Darnton]

Oh, OK, that's clearer. Yes, there is a wider arch in the center than at the ends. What that does is permit the overall shape of the arch to be more cylindrical, rather than what's called a figure-eight arch, which isn't good. So you're doing the right thing. I would ignore the Sacconi drawing.

[Mark Sullivan]

Does the cylindrical shape help the top resist the forces of string tension, and the tendency of the neck projection to decrease?

[Chris Knowlton]

Hello again Michael. Thank you for your responses. I'm afraid that I did not describe the issue very well.
I see what you are referring to, but I am talking about the area from the widest point in the lower bout to the bottom of the plate, and specifically the area from the edge of the plate to around 30 – 35mm in from the edge. In this area my contour lines are not concentric. As they move from the widest point on the lower bout down to the bottom of the plate, they become closer together. (This means that the concave area at the bottom of the plate becomes convex sooner than it does at the widest point in the lower bout.)

Shouldn’t the contour lines in this area be concentric, or close to concentric?
_________________
I make sawdust mostly

[Michael Darnton]

That's the question I answered. You need to look at it differently--you're too focused on the scoop, not enough on the arch. Narrower scoop (that you're pointing out) means the wider arch that I pointed out in that area. The defect in old German violin making is that they thought like you're thinking, and ended up with the scoop all the same, and a figure-eight arch. Rather than a unified arch supported by a varying scoop. And the problem here is that Sacconi, with his lines, is encouraging you to think about things from the wrong direction.

[Chris Knowlton]

Thank you for hanging in with me. I finally get it. I was being pulled in by the Sacconi diagram and my own tendency to simplify.

Chris
_________________
I make sawdust mostly

[Michael Darnton]

Mark, I think of instability as the result of a mistake, not a design thing. Violins made right are stable on their own; you have to do something out of the normal range to have a failure. In this discussion, both types of arch are stable, if they're not taken to extremes. Either type of arch can fail if done wrong.

[Janito]

Michael

Now I am a little confused.

Having only seen a very few Strads, and mostly relying on memory, I have worked on the assumption that the contours of a Strad would follow a figure of 8, more or less. The spacing of the contour lines, as on a geographical map, would then vary depending on the slope angles, ie the arching.

Are we saying the same thing?

[Michael Darnton]

As long as the violin is shaped like a figure eight the arching is going to have some of that tendency. The point is, how far away can you get from that without going grotesque? The Cremonese accomplished that very gracefully, whereas a violin like this does not:

[Janito]

I understand.

Do you have a good example photographed from a similar angle to show the contrast?

[mikemolnar]

a unified arch supported by a varying scoop - Darnton

Wow. This is exactly what I noticed a month ago after laying out the Milanollo.

Mike

[Andres Sender]

Janito, a few relevant finds, although not exact:

http://www.stringsmagazine.com/Media_Files/articles/153/17873/153-17873-img001.jpg

http://www.daylife.com/photo/02WJ0XUegx2Qf

[Janito]

Thanks Andres.

These are the sort of photos that help to translate a 2D drawing into a 3D mental image.

Incidentally, the Strings photo does suggest that the F fluting may have emerged initially as a product of the cylndrical central area...