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Belly vs Back Arching Asymmetry


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9 hours ago, Dennis J said:

For bulging to occur at the upper and lower bouts the height of the arch in those two places would have to rise in relation to the plate's edge position.

So, is it bulging of the upper and lower bouts or bending at the waist?

Both.

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8 hours ago, David Burgess said:

That is not the claim, and your repeated failure to comprehend this is why we keep going in circles.

As I already stated in the other thread, we don't know what the original arching was. But what we do know, or should know, is the characteristic way in which tops distort with string loads. Is it possible that some makers 300 years ago copied archings from even older instruments which were already distorted, as some makers do today? Yes. Is it possible that  some makers started with a more peaked long-arch on the top than the back, anticipating from experience or training the way in which they would distort, rendering them with an arching more similar to that of the back years later? Yes.

Are you done now? :lol:

Please print this post, tape it to the wall next to your computer, and re-read it before posting another claim claiming that a claim is something other than it was. :D

We did this one before.  

1 of 10 times you give the half disclaimer.

We both agree that 'distortion is real'.

But my hypothesis is 'distortion is real' AND 'that ALL those old instrument were carved with essentially the same character of the old top arches as we see them today.

Despite you 1 in 10 moderated disclaimers, 9 of 10 you speak as if 'distortions are real' means 1) my hypothesis is absurd or even dangerous, and 2) that distortion is why we see the characteristics top arches we see today - but they didn't have that character origunally, that they were through arched.

And even in the 1 in 10 times when you retreat to your disclaimer as above, it's very limited.  'Some', 'might'.

We aren't talking about 'some'. ALL show this characteristic top shape.  Either ALL were carved basically that way, with distortions playing a secondary non-game changing role.  Or ALL weren't carved that way, wirh distortion playing the primary role in the top arch character we see today in ALL the old examples.

Because of this, your half disclaimer with its 'SOME' and 'MIGHT' is just meaningless obfuscation away from what you believe and generally say.

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36 minutes ago, David Burgess said:

Nope. I can confidently state that there are no violin arches which have not been distorted with string forces, and time, unless they were never stung up or used.

Just repeating your favorite false equivalency.

We both agree that all violins experience distortion.

That does not mean that those distortions are the primary factor in giving the old top arches the basic character we see today.

It DOES NOT mean there weren't originally carved with the basic character of the top shapes as we see them now.

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6 minutes ago, David Beard said:

Just repeating your favorite false equivalency.

 

What exactly is this supposed "false equivalency"? Are you going to rely on vague and non-specific "accusatory terminology" to try to establish anything resembling reality?

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13 minutes ago, David Beard said:

Just repeating your favorite false equivalency.

We both agree that all violins experience distortion.

That does not mean that those distortions are the primary factor in giving the old top arches the basic character we see today.

It DOES NOT mean there weren't originally carved with the basic character of the top shapes as we see them now.

You 2 can both be right.  Here's how it went down according to me.  In the beginning some luthiers made their belly plates too thick and their violins sounded bad.  Others made their bellies too thin and they sounded good until they cracked.  But a few got it just right and they were thin enough to sound good, but thick enough they wouldn't crack... They just sagged a little. That's how you know you got it just right.  A little sag in the middle.

 

That's how they KNEW they had a good violin. A little sag in the middle.  Perfect belly thickness.  So now, when someone wants to make a violin that everyone will think is perfect, they will carve a little sag in the middle.  That way you can err on the thick side and ensure the belly won't crack yet fool the buyer, and make them think the belly was carved exactly perfect and is sagging just a bit.

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5 minutes ago, David Burgess said:

What exactly is this supposed "false equivalency"? Are you going to rely on vague and non-specific "accusatory terminology" to try to establish anything resembling reality?

The false equivalence is jumping from 'some degree of distortion is real' to 'distortion is the Primary cause for the character of long arch we see in the old instruments'.

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10 minutes ago, Bran Latebarie said:

You 2 can both be right.  Here's how it went down according to me.  In the beginning some luthiers made their belly plates too thick and their violins sounded bad.  Others made their bellies too thin and they sounded good until they cracked.  But a few got it just right and they were thin enough to sound good, but thick enough they wouldn't crack... They just sagged a little. That's how you know you got it just right.  A little sag in the middle.

 

That's how they KNEW they had a good violin. A little sag in the middle.  Perfect belly thickness.  So now, when someone wants to make a violin that everyone will think is perfect, they will carve a little sag in the middle.  That way you can err on the thick side and ensure the belly won't crack yet fool the buyer, and make them think the belly was carved exactly perfect and is sagging just a bit.

No.

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1 hour ago, Bran Latebarie said:

Not sure what you're saying no to.  My version of history or if you can judge how well a belly has been carved by how much it bends when strung and tuned?

All of it really.

I can't agree on your version of events for early violins at all.
Also, when it comes to wood, it is quite elastic in certain ways. Therefore, while too thin could crack, it is much more likely to distort massively first, before the stress would lead to cracks, unless it's so thin that it can't even support a moderate load.

I can't see a practical situation where carving in a sag is beneficial, or how this would lead anyone into the thinking that the thickness for that given belly was then correct as a result of this.

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On 3/9/2021 at 1:17 AM, Shunyata said:

I would like to make sure I properly understand a subtlety.

The long arch has a high point in the middle of the plate and slopes down to the top and bottom edge of the plate.

For backs it seems like the arching is typically symmetrical - the top-side arch and bottom-side arch are mirror images.

For bellies it seems like the bottom-side arch is very similar to the back.  But the top-down arch is rather different.

The belly top-side arch seems to stay flatter as you move from the center, then fall more steeply once you cross the upper bout wide point.

Do I understand this properly?

Having had a good look at the design of long arches I think I can shed some light on this subject.

I think early makers must have had a basic profile design in mind. So, rightly or wrongly, some characteristics seem evident to me.

Some early makers made high rounded top arches and some made lower flatter versions. Typically the recurve at each end is shorter than that of the backs.

As far as the high point is concerned, particularly on the flatter version, the profile shape is clearly fuller in the upper bout than the lower, just as you say. I think that necessitates a high point well forward of the centre to produce a smooth, shallow curve.

The back long arch is much less flattened, but I think the highest point of the arch should still be forward of centre which will again introduce some asymmetry into the long arch profile. And its most significant characteristic is that the recurve at each end is much longer than that of the typical top long arch.

 

 

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12 minutes ago, David Beard said:

I would be very interested to see even one old Italian example of this.

Can you post even just one example?

Is this the only thing you find questionable in my post? I'm surprised.

Is Stainer early enough? I'm sure I saw some Amati high-arch pics posted recently. Forget to which one they were attributed.

Does the country of origin really matter?

I go by the apparent design I see and use a little intuitive reasoning to understand the rationale behind it.

 

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22 minutes ago, Dennis J said:

Is this the only thing you find questionable in my post? I'm surprised.

Is Stainer early enough? I'm sure I saw some Amati high-arch pics posted recently. Forget to which one they were attributed.

Does the country of origin really matter?

I go by the apparent design I see and use a little intuitive reasoning to understand the rationale behind it.

 

So, where is that Stainer example? Or other example if you prefer.

As far as I've been able to observe, these flattish stretches of the top are present in all Cremona examples, at least into 1770s.  And, though I haven't explored as thoroughly, it seems to be in all the older Italian violin making.

If there are counter examples, I'd like to know about them.  But I don't think Stainer is where you'll find them.  I believe Guadagnini might have experimented with nearly dissapearing the flattish component of the top arch.

But as far as I'm aware, no one didn't use this flattish feature until the modernized French making in the 1800s.

I am truly interested in learning more about the boundary lines between these styles.  So, I don't mean to come off facetiously in challenging you to produce actual examples.  If such example really exist, I'd like to see them.

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Yes, I was a bit out my depth there. I was pretty sure Stradivari didn't do high rounded arches, but what is the story regarding the Amatis? My take on it is that arching was either rounded and higher or lower and flatter, broadly speaking.

I don't think the style really matters as long as the central area is made strong enough to avoid sinking. I can understand why that outcome is disastrous.

 

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34 minutes ago, Dennis J said:

Yes, I was a bit out my depth there. I was pretty sure Stradivari didn't do high rounded arches, but what is the story regarding the Amatis? My take on it is that arching was either rounded and higher or lower and flatter, broadly speaking.

I don't think the style really matters as long as the central area is made strong enough to avoid sinking. I can understand why that outcome is disastrous.

 

Look at examples.  Low or high, they all have the flattish stretch.  All the families.

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35 minutes ago, Dennis J said:

but what is the story regarding the Amatis? My take on it is that arching was either rounded and higher or lower and flatter, broadly speaking.

The Amati family worked for approx 200 years in total, and during that time, the arching style progressed significantly. It's rather more complex, than rounded and high, or a bit lower and flatter.

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7 minutes ago, David Beard said:

Look at examples.  Low or high, they all have the flattish stretch.  All the families.

Yes I don't disagree. I've experimented duplicating similar profiles using your favourite drafting tool, the french curve. The fall in the central area is very slight in the flatter examples.

 

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Here's an alternative theory.  Design is based on a Bruneschelli dome.  The big flat area provides no structural strength and is not meant to be under much tension or compression.  It's like covering the skylight in the Florentine dome with a thin membrane.  This allows the violin to have a big, thin area in center and acts kinda like a drum.

 

Revolutionary design for the period.  Before this they typical Florentine arch is characterized more like the back of a violin.  Much thicker in the center than at the edges.

This is pretty contemporary with the golden violin age and everyone would have known about the Bruneschelli dome, 1420.  Still cutting edge today.  Can't do better without steel reinforcement.

dome.jpg

arch.jpg

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1 hour ago, Bran Latebarie said:

Here's an alternative theory.  Design is based on a Bruneschelli dome.  The big flat area provides no structural strength and is not meant to be under much tension or compression.  It's like covering the skylight in the Florentine dome with a thin membrane.  This allows the violin to have a big, thin area in center and acts kinda like a drum.

 

Revolutionary design for the period.  Before this they typical Florentine arch is characterized more like the back of a violin.  Much thicker in the center than at the edges.

This is pretty contemporary with the golden violin age and everyone would have known about the Bruneschelli dome, 1420.  Still cutting edge today.  Can't do better without steel reinforcement.

dome.jpg

arch.jpg

So you think you see a pointed peak at high point of top arches?

You have very imaginative eyes.

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8 hours ago, David Beard said:

None were rounded. None. From any family.

No one stated that in this or the other thread. You managed to bring that into your post by misreading or misinterpreting others' posts. Have you seen any of Strads when they were new, before stringing? Assuming that they started as flat as we see them now is similar as assuming all the rusty cars we see started rusty.

Let's not forget that wood is not only elastic but also plastic. That means that the wood sets in new shape after some time. And that doesn't have to show in all dimensions. The edges are stiffened by gluing to ribs so the longitudinal compression shows mostly along axis. There are companies that produce pre-compressed wood (used for bending) compressed as much as 10-15% shorter than their original length (of course they use steam chambers) but he width and height is held the sam during the process by pressure from sides. This also happens on any compressed wood piece at a very slow pace.

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13 hours ago, David Beard said:

The false equivalence is jumping from 'some degree of distortion is real' to 'distortion is the Primary cause for the character of long arch we see in the old instruments'.

Why do you keep inventing my positions, when I've posted my real ones in both threads? Are you looney-tunes or something? :rolleyes:

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