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5 minutes ago, John Harte said:

However the question remains as to whether at least some flattening through the central region of belly long arches was the norm when originally made. Very late period del Gesu belly longitudinal arches are an interesting study.  If you consider instruments like the Ole Bull, Sainton, Leduc, Prince of Orange and the Hennel Rose etc., the belly longitudinal arches as they appear today are somewhat rounded, similar to their longitudinal back arches.  Maybe del Gesu was mindful of the potential for belly distortion and was particularly concerned given the very long f-hole profiles that he was tending to use at that time......???........

Quite possible. And he would have had a chance to observe violins which had already been around for quite a while, so maybe that gave him some notions about how they could be made more stable?

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So, David Burgess seem to be proposing that not only does the soundpost and bridge cause various kinds of minor distortion in top plates as an instrument ages, but that this is 'The Reason for the Flattish Stretches' in classical Cremona tops.

Is that long top arch shape carved by the maker, or merely age and distortion??

So let's examine this proposition.

The first part of this is the idea is that distortion and aging rather than the makers original carving give us the flattish portion we now see in classical long archs.

Because the bridge and post can cause some distortion, Burgess is saying that's whole story.  

Why?  Because distortion does happen, and we examples like the 1714 'DaVinci' Strad.

907321748_1714StradDaVinciwholebodysideview.jpg.73231e4809e792c56d9a4b6e7ec0352f.jpg

We can see in this example that the area around the bridge has in fact caved in significantly.  But the Burgess claim also requires believing that the top long arch started out much like the back, and then the pushing down at the center also pushed the top's long arc out and up to the current shape we see.

Is that sensible?    To be 'the one and only reason' for these flattish stretches,  this hypothesized distortion would need to explain ALL the observable classical example, not just parts of some examples.

Is that sensible?

Here are two xRays of early Cremona examples.  A 1560c Andrea Amati, and a 1595c Brothers Amati.

1076938332_1560cAndreaAmati(2).thumb.jpg.2a1709292d3c250e7fe97174011e3e8d.jpg

330495899_1595cBrothersAmativiolinKingHenryIV(3).thumb.jpg.997313d94f97c461c280a7f4463df4b3.jpg

Notice in these an additional feature of classical long top arches.  One consequence of the extended flattish area is that the long top arch retains most of its height through this stretch, and then falls down to the edge at the end blocks more precipitously in consequence.  Looking a this and other examples, we can see how the carving and thicknessing approaching the blocks all relate to this angle of decent. 

Our we to also believe that distortion forces from the bridge and post area recarved these areas?????

So let's look at the contrasting approach.   And, actually, Vuillaume doesn't completely depart from the classical example in every instrument. He only retreats from the long flat stretch.  You can see there's still a nod to the old idea present.  It is in later modern examples that we see the idea completely tossed out.

Vuillaume examples from 1865c and 1871c:

 

1130495169_1865cviolinJBVuillaume(1).thumb.jpg.2ec5dc8d4602cc4282fa15d040b16bb2.jpg

 

48727302_1871cviolinJBVuillaume(3).thumb.jpg.420c181da89e5bd94f5f4363c6d1173d.jpg

So he hasn't eliminated the feature, just limited the extent to which he honors it.

Compared to Lupot in a 1808 example:

1679299735_1808Lupot.thumb.jpg.d651248841b12e3662aa9d74ee6749e1.jpg

 

Or here in an 1810 Ceruti:

2014230882_1810GBCerutiviolin(7).jpg.1c6a2f5f154adb24f6f89314269137e8.jpg

This feature of a flattish stretch in the top's long arc is not simply some basically random deformation.   It's implementation varies with families and fashions across the generations of Cremona making.  It is a product of the maker's choice and doing, not some mechanical accident of time and distortion.  

And here is a last example of a younger instrument, showing a very full version of this feature, not because it had longer to age, but because the maker is just more connected to old Cremona ways than most of his contemporaries.

1894 Rocca:

1284531276_1894EnricoRoccasideview.thumb.jpg.98a43db3dd486f1881a68aba885193a3.jpg

 

 

 

 

 

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Mr. Beard, you are making this more difficult for yourself than it needs to be.

Since you don't seem to have a good intuitive grasp of the ways things distort under various forces, haven't I suggested before that you take a new never-strung instrument of thinnish grads (such as those of a Strad), make long arching templates, string it up and expose it to a variety of environments (particularly some very high humidity), then check it against the original template? Have you done this yet? Why not? I did this decades ago to double-check my thought process.

Notice the light between the top, and the original template.

archingdistort.jpg.e340b7ec21f035a7fc14574fad17b5b9.jpg

 

Perhaps this experiment should be part of "boot camp", or basic training for anyone who wants to be a fiddle maker. Some trends will be evident rather quickly. It will take longer for severe distortion to occur, but if you are impatient, you can accelerate this by tuning the violin a major third higher, and cycling the relative humidity between 90% and 50% every two weeks.

No, I am not claiming that this totally explains the flatter section on the top of every instrument. There are makers today who either believe the old instrument were made that way, or believe that even if this is a result of distortion, that it is one of the reasons older instrument are reputed to sound superior, so they make their instruments that way. Can't rule out that some older makers might have had similar notions, or that others might have started with a rounder long-arching on the top than on the back, anticipating this distortion, resulting in a "flat" section (or even a reverse curve) being less evident today.

Without having seen these instruments when they were first made, we simply don't know for sure. Nobody does, not even you! :D

 

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9 hours ago, David Beard said:

And here is a last example of a younger instrument, showing a very full version of this feature, not because it had longer to age, but because the maker is just more connected to old Cremona ways than most of his contemporaries.

1894 Rocca:

1284531276_1894EnricoRoccasideview.thumb.jpg.98a43db3dd486f1881a68aba885193a3.jpg

Your suggestion that Enrico Rocca was more connected to old Cremona ways than most of his contemporaries is questionable

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It seems obvious to me that there are plenty of old and some not so old violins which have sunken or distorted areas at the bridge position and bulging toward the upper bout.

That's apparent with high arch and low arch examples. Surely that's just the result of overly thin tops.

I've found making top and back templates for the long arches involves very delicate control of those different curves.

It's only possible using a french curve after deciding the highest point's longitudinal position. Without a good examination and understanding of the exact geometry of both the top and back curves speculation is meaningless.

David Beard's Rocca example looks to me an ideal example of what many top makers have aspired to. The top is slightly flattened and the high point of the arch is quite possibly forward of the bridge. The back is more rounded and also has a longer recurve at each end.

 

 

 

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5 hours ago, David Burgess said:

Without having seen these instruments when they were first made, we simply don't know for sure.

I think it might be possible to use high resolution CT scans to find out more.  

With a sunken arch at the bridge, the crossarch will be flattened, and if you look with CT scans at the spacing relation of the annular rings (in cross arch section), they will be compressed on the outside surface and expanded on the inside.  The reverse will be true in the upper an lower bouts.  So by looking at the relative angles of the annular rings, you might be able to back-calculate what they might have been originally, thus the original cross arching, and from there, estimate the long arch.  I am not a CT expert, but from what I've seen, it seems like it should be possible to do this.

1274752997_CTscan.thumb.jpg.06ab71bd4f2cf186e9f98b5170e32d88.jpg

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12 minutes ago, David Burgess said:

If one wanted the strongest long-arch, given the way a violin is loaded, it would be close to straight lines from near the bridge feet, to the upper and lower blocks  It might be too rigid to sound very good though. :D

If I ever get to where I have time to mess around with non-productive work, I want to knock out one of those on the CNC to find out.

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3 hours ago, plasterercaster said:

Your suggestion that Enrico Rocca was more connected to old Cremona ways than most of his contemporaries is questionable

Well, at least in that long arch choice.

That instrument shown is 1894.  In late 1800s, many people are copying Cremona examples, but mostly with different modernized means.  And the aren't necessarily copying every feature of the old instruments. Some more than others.

My point is that which instruments show a long flattish top is much more about who made the instrument than about when.

 

 

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43 minutes ago, plasterercaster said:

Considering that the bridge is still on this instrument your template is well off the centre line/long arch. Do you have an equivalent picture of the back?

The template was made in that position, up against the treble side of the fingerboard.

No, I don't have a similar picture of the back, but changes on the back are much smaller. I'm pretty sure I don't even have the top template any more. This photo was taken a long time ago.

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7 hours ago, David Burgess said:

No, I am not claiming that this totally explains the flatter section on the top of every instrument. There are makers today who either believe the old instrument were made that way, or believe that even if this is a result of distortion, that it is one of the reasons older instrument are reputed to sound superior, so they make their instruments that way. Can't rule out that some older makers might have had similar notions, or that others might have started with a rounder long-arching on the top than on the back, anticipating this distortion, resulting in a "flat" section (or even a reverse curve) being less evident today.

We both agree that some degree of distortion occurs.

But you have often pointed to such distortion in the context of 'this is why the classical instruments have a long flattish part in the tops'.

 

There's a big between 'plates distort some', and 'plate distortion'  is the total cause of the classicsl Cremona plate shapes we see today.

You've never made even a weak case that one thing gives the other.

You have only ever demonstrated that 'some distortion' occurs. As far as I know, no one disagrees with that.

But your leap to claiming that alone shaped the classical long archs is groundless.  

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1 hour ago, David Burgess said:

If one wanted the strongest long-arch, given the way a violin is loaded, it would be close to straight lines from near the bridge feet, to the upper and lower blocks.  It might be too rigid to sound very good though. :D

IF...

What is most desirable IS the question at hand.

Perhaps your assumption that the strongest shape is most desirable is just that, an assumption.

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1 minute ago, David Beard said:

Perhaps your assumption that the strongest shape is most desirable is just that, an assumption.

Dynt never claim no such ting. Didn't you just quote me saying,  " It might be too rigid to sound very good though".

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17 minutes ago, David Burgess said:

Dynt never claim no such ting. Didn't you just quote me saying,  " It might be too rigid to sound very good though".

Ok. Sorry I didn't read you correctly.

That's good. So at least we agree that 'strongly engineered' isn't the universal end goal.

But, I urge you to reconsider if you truly think the distortion you point to can actually be sufficient to explain the full range of Old Cremona examples, and the related details.

I say no.

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1 hour ago, Don Noon said:

I think it might be possible to use high resolution CT scans to find out more.  

With a sunken arch at the bridge, the crossarch will be flattened, and if you look with CT scans at the spacing relation of the annular rings (in cross arch section), they will be compressed on the outside surface and expanded on the inside.  The reverse will be true in the upper an lower bouts.  So by looking at the relative angles of the annular rings, you might be able to back-calculate what they might have been originally, thus the original cross arching, and from there, estimate the long arch.  I am not a CT expert, but from what I've seen, it seems like it should be possible to do this.

1274752997_CTscan.thumb.jpg.06ab71bd4f2cf186e9f98b5170e32d88.jpg

Yes.  There are a number of testable details.  If Burgess's hypothesis were correct, certain parts of the plate have been pushed down, certain parts have been pushed up and out.  And certain parts have been stretched. 

Also, there's the very interesting question of how the center of the plate can be depressed enough to distend the far reaches of the long arch, while the center area cross archs don't seem to have absorbed anywhere near that degree of depression?????

David, notice that in your photo the plate distortion is barely equal to a plate thickness.  But, to explain some classical examples, the movement would need to be greater than a full centimeter.

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7 hours ago, David Beard said:

David, notice that in your photo the plate distortion is barely equal to a plate thickness.  But, to explain some classical examples, the movement would need to be greater than a full centimeter.

I only ran the test for about a year. Don't exactly remember how long. A full centimeter of arching distortion is probably quite a bit more than I have noticed (on a violin), though.

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There's no need for such stretching/compression at all. If we simplify the arch somewhat and calculate with smooth circle arc long arch then shortening the top outline by mere 1mm in length will cause almost 4mm bulge of arch in center (assuming there won't be any wood fiber compression aong the top). Now, if you force the apex with bridge to stay at the same height the bouts will bulge drastically...

Arch.gif

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6 hours ago, HoGo said:

There's no need for such stretching/compression at all. If we simplify the arch somewhat and calculate with smooth circle arc long arch then shortening the top outline by mere 1mm in length will cause almost 4mm bulge of arch in center (assuming there won't be any wood fiber compression aong the top). Now, if you force the apex with bridge to stay at the same height the bouts will bulge drastically...

 

Thanks for your analysis. I get a little revved up whenever analysis aligns with my observations. ;)

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6 hours ago, HoGo said:

There's no need for such stretching/compression at all. If we simplify the arch somewhat and calculate with smooth circle arc long arch then shortening the top outline by mere 1mm in length will cause almost 4mm bulge of arch in center (assuming there won't be any wood fiber compression aong the top). Now, if you force the apex with bridge to stay at the same height the bouts will bulge drastically...

Sure, the gross length of the arch can remain constant, and most likely will, due to the extreme longitudinal stiffness of spruce.  There is some small amount of stretching/compression of the inner and outer surfaces due to bending, but not much.

The crossgrain is something else.  If the bridge area flattens out, either the crossarch has to bubble up near the ribs, or (more likely) the ribs will be pushed out.  The opposite will happen in the upper and lower bouts, with the ribs getting drawn in as the arch is pushed up.  There's probably not much alternative in the upper and lower bouts, other than crossgrain stretching... which would be a big split-inducer.

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