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Andreas Preuss

Stradivari's secret was a concept?

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Just now, Urban Luthier said:

This is the coolest thing I've seen posted here in ages!! thank you.

I do have a question however to make sure I'm using this correctly.

I assume one has to subtract the edge thickness from from the total arching height for the calculator to generate the correct curve. For example on the viola I'm working on, the back arch height at the lower bouts is 12.7mm. To get the correct cycloid, I presume I enter 7.7mm into the height field. (12.7 arch height - 5mm rough edge thickness).

I tried it and this appears to be correct but I'd love someone verify I'm doing this right!

Is this correct? 

 

I've used this program which also has detailed instruction for each parameter entry.  http://jpschmidtviolins.com/cycloid.html

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23 minutes ago, Davide Sora said:
 

Stradivari must have had a really bad memory, if for him it was necessary to mark on every form a single number (32) to remember it for its proportional calculations.:)

I'm just joking, I respect and I consider interesting your and others attempts to identify a system of design, but I have a little trouble imagining a prolific workshop like that of Stradivari where they wasted time with this kind of thing.

And yet the marks are there (two arcs, always slightly different) so apparently they did feel this need. I guess your imagination needs a rebuild. :-)

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20 minutes ago, Urban Luthier said:

This is the coolest thing I've seen posted here in ages!! thank you.

I do have a question however to make sure I'm using this correctly.

I assume one has to subtract the edge thickness from from the total arching height for the calculator to generate the correct curve. For example on the viola I'm working on, the back arch height at the lower bouts is 12.7mm. To get the correct cycloid, I presume I enter 7.7mm into the height field. (12.7 arch height - 5mm rough edge thickness).

I tried it and this appears to be correct but I'd love someone verify I'm doing this right!

Is this correct? 

 

Not quite. You need to measure to the bottom of the final scoop not the rough edge. So, about 9.2mm or so.

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32 minutes ago, Michael Darnton said:

And yet the marks are there (two arcs, always slightly different) so apparently they did feel this need. I guess your imagination needs a rebuild. :-)

In fact, also remembering the height of the ribs (the most common interpretation for these arches) is not so difficult to require a reminder marked on the form....:rolleyes:

This is one of the reasons why I think your interpretation is still intriguing and one of the most probable (along with the height of the ribs).:)

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I just checked Francois Denis' book. No mention of the scribed arcs that I can find. Unfortunate, since a number of the circles he uses are exact multiples of that ~32 number. . .  or would be better if they were. I have spent quite a time mapping circles on the forms, based on tidy multiples of ~32mm, not fractions thereof. As I said, they're everywhere. They're enough to make me wonder if there wasn't just one set of disks that were used in the shop rather than incremental multiples of whatever small increment was on each form, and that the curves are all the same, even though the proportions vary a bit from mold to mold.

That would be rational, right? Why make a 128.2mm disk when you already have a good-enough 127mm one or something similar. Then build your proportional box, as Denis did, and push your circles up to the box edges and trace, rather than using a compass. The important part is the circles, not their centers, anyway. The forms don't vary enough to make new circles. Then the arcs would be a record of the actual theoretical measure for that form, for calculating linear locations that aren't circles, such as neck length, scroll size, etc.

Just thinking out loud. . . .

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5 hours ago, Michael Darnton said:

This is not my idea--there was an article by Quentin Playfair in the late 90s in STRAD that kicked this idea into my mind

The Playfair article may be read at http://www.platetuning.org/Cremonesesarching_Part_1.pdf

He says of Galileo, "His suggestion that a pure cycloid would make a suitable arch for a bridge was put into effect many years later in the construction of the Ponte di Mezzo over the Arno in Florence." (I have not checked that.)

Is it not self-evident that a Cremonese maker is far more likely to have adopted cycloid arching for strength than for any supposed acoustic effect?

So at what date was this idea that a cycloid gives great strength in the public domain? Galileo mentions he had the idea of its possible suitablility for a bridge 40 years earlier in a letter in 1640. The bridge was finished 1660 (ref Wikipedia). So if Galileo's statement is correct, and the statement about the bridge is correct, the idea that the cycloid is especially strong became known between 1600 and 1660.

My suggestion that Cremonese makers used cycloid for strength is weakend if it appears in violins before 1600. Does it?

It may be worth reviewing the work of Dürer on cycloids to which Playfair refers. Playfair does not suggest why Cremose makers may have used the cycloid, he only points out that they were potentially aware of it.

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On 7/25/2018 at 9:40 AM, Torbjörn Zethelius said:

1.   the distance between the upper and lower blocks equals the original vibrating string length. . A simple way to do this without a calculator at hand is to use a (fairly stiff) string the length of the distance between upper and lower blocks, and make a circle of it. The diameter is the width of the c-bout.

2.  I haven't checked it in a long time, so I'm not sure if it works on all the Strad moulds. It should work on at least one. The approx ≈32 mm is then 1/10 of the vibrating string length. ;) 

1.  Using a beef stew can, making a mark on the bottom and then rolling across a line with the length between the blocks I can say yes, this will work with my 1733 DG and Bagatella math method formas.  I should say this works if one leaves out the edge overhang and possibly all of the rib thickness.

2.   Using the same method my 1709 Strad showed a 3-4 mm difference but obvious to me I tried the same radius as used for the first two formas when I should of used a slightly wider radius.  Good enough for me. 

Edited by uncle duke
need another sentence to #1.

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On 4/24/2018 at 8:07 AM, Don Noon said:

Personally, I think that the 300 year age difference has something to do with it.   Wood properties do change with age and/or exposure to air.

I've often had Don's exact thought, but then I remembered that Strads were praised when they were only decades old.  But I still agree with Don that age has contributed to their quality.  My guess is that the wood has continued to dry and lose density.

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44 minutes ago, John_London said:

Is it not self-evident that a Cremonese maker is far more likely to have adopted cycloid arching for strength than for any supposed acoustic effect?

So at what date was this idea that a cycloid gives great strength in the public domain? Galileo mentions he had the idea of its possible suitablility for a bridge 40 years earlier in a letter in 1640. The bridge was finished 1660 (ref Wikipedia). So if Galileo's statement is correct, and the statement about the bridge is correct, the idea that the cycloid is especially strong became known between 1600 and 1660.

 

The cycloid has a couple of interesting properties of which two or three ( one might speculate ) have a direct relation with the functioning of a violin. 

"Strength" is not one of them. There is a book by Richard Proctor on cycloids should one wish to get an analytical grip on the subject. Book is excellent and pretty elementary. 

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2 hours ago, John_London said:

Is it not self-evident that a Cremonese maker is far more likely to have adopted cycloid arching for strength than for any supposed acoustic effect?

So at what date was this idea that a cycloid gives great strength in the public domain?

A cycloid is one particular class of mathematically generated arc, with no a-priori benefit for strength or acoustics.  Certainly if you use a fuller cycloid with inflections, it would make the most stupid bridge.  If you only use the middle arc, then it's an arch, and it depends on how you are loading it, supporting it, and what materials you  use if you  want to find out how "strong" it is.  For example, if you have uniform loading, fixed at the ends, and want to have purely compression along the surface, then an inverted caternary is what you'd want.  Lots of structures use a plain arch with a single radius, 'cuz it's easy to make and it's strong enough.

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I think Kevin Kelly and Ben Ruth produced rulers divided into Cremonese Points. They came up with 1 point = 3.5mm based on a statistical analysis of Stradivari's forms and the work of F Denis. 

 

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7 minutes ago, curious1 said:

They came up with 1 point = 3.5mm 

Pretty close to pi +.1e.  Oh those clever Cremonese.

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3.5mm = 1point works with the f hole layout well also.

sacconi mentions that the two parallel lines laying out the f holes are ~7mm apart (2 points). The distance from the c bout edge to the center of the upper eye is often ~31.5mm (9 points). The distance between the centers of the upper and lower eyes is usually ~63mm (18 points).

07A979C3-258B-4AB0-9171-A80A18C684EC.thumb.jpeg.5aa13336a40ea1e04bf5cc19deb31353.jpeg

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7 minutes ago, Don Noon said:

Pretty close to pi +.1e.  Oh those clever Cremonese.

Haha. :P 

When did the millimeter first appear as a unit of measure?

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I haven’t thought about this stuff for quite awhile. I’m not so interested in what the Cremonese did but more in just what makes a violin work well. If i stay focused on that our paths might intersect at some point.

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7 minutes ago, curious1 said:

Haha. :P 

When did the millimeter first appear as a unit of measure?

Looks like mid-late 1800's.  So they were not only clever, but could see the future.

1 minute ago, curious1 said:

I’m not so interested in what the Cremonese did but more in just what makes a violin work well..

Me too.  

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19 hours ago, David Beard said:

I think that very possibly it was a guiding idea in Andrea Amati's original design, and continued by his family.   But as you yourself point out, it doesn't continue through the generations.

But the executions I'm pointing to do. And the choices in these methods leave enough flex so that Amati's who wanted to could push the choices around to give the results you point to.

Actually when I prepared a lecture on this, I found out that Andreas Amati didn't set his f-holes this way. Trying to track it back from pictures I found, it must have come from Niccolo Amati when he was still working with his father. But that's not written in stone.

 

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I used to think that Nicolo was the clever one, but then a couple of months ago I had to prepare a lecture, and when I got to the f-hole section I suddenly realized that one of the Brothers was the smart one, and that Nicolo kind of messed up everything he touched, not just the f-holes, which violin making took a very long time to recover from--around 1696 for the Stradivari family, for instance. I think the modernization of Andrea's f-holes and layout happened a bit too early for Nicolo to be involved, from what I could figure out.

I got a whole new respect for the Brothers from prepping that lecture!

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8 minutes ago, Michael Darnton said:

I used to think that Nicolo was the clever one, but then a couple of months ago I had to prepare a lecture, and when I got to the f-hole section I suddenly realized that one of the Brothers was the smart one, and that Nicolo kind of messed up everything he touched, not just the f-holes, which violin making took a very long time to recover from--around 1696 for the Stradivari family, for instance. I think the modernization of Andrea's f-holes and layout happened a bit too early for Nicolo to be involved, from what I could figure out.

I got a whole new respect for the Brothers from prepping that lecture!

I'd love to hear the lecture! I have always treasured the Brothers. I wonder which was the primo...

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At this point, I'm inclined to think that Hieronymus I was the smart one of the family. It appears that by 1604 he was already on top of the f-hole problem, for instance. My personal opinion that my favorite f-hole is one of his (this one isn't from 1604, but it could have been.)

 

amati-f.jpg

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1 hour ago, Michael Darnton said:

Guys, that kind of sounds like wanting to learn French, but purposefully avoiding talking with any actual French people or listening to any French. 

Actually eveyone’s obsession with the Cremonese is like thinking only the French can speak the language of love. 

The laws of the physical world are not a creation of man.

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I'm not aware that the laws of the physical world had a thing to do with creating the violin. They only try to explain it, and not too skillfully, by the way, so far.

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1 minute ago, Michael Darnton said:

I'm not aware that the laws of the physical world had a thing to do with creating the violin.

Ya, that’s most peoples problem.

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