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the function of arching shape


reguz

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3 hours ago, martin swan said:

Sorry but it seems to me to be the height of battiness to study the arching of violins in isolation.

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No two violins with the same arching will sound the same ...n unless perhaps made with 4mm ply.

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I'm now using 0.8mm Finish birch 3 ply plywood for everything--top, back, and ribs to keep simple, inexpensive, light and reproducible.  The top plate is flat to avoid arching arguments.

For violas the lightness helps keep the f holes well above the water line.

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This whole discussion is predicated on the assumption that arching, particularly the top, can be varied by the maker to enhance tonal outcomes.

I think that is probably true but all arching starts with the long one which fixes chosen heights along its length. And these heights will largely determine cross-arch profiles.

More manipulation of shape is possible with higher arching, particularly in the upper and lower bouts.

The inflection point position at the waist, upper and lower bouts determines the final arching shape overall. That is arching reality. As well as that a smoothly modulated arching shape requires synchronisity between centre bout, corner inflection points and lower and upper bout inflection points.

Those fundamentals need to apply whether an arching is planned or done freehand for a successful outcome. Doing so with templates at least ensures that ideas about tonal outcomes can be rationally pursued. Any other method is based on pure guesswork.

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15 hours ago, reguz said:

Dear violions88. If I was able to do what you aske for I certianly for long time ago would have done but as you must know I only study one specific structure and hope to learn fram that. However, there are specific conditions we find on all violins and these are described and it might be possible you have not tought about it. If you study the N Harris thesis carfully and undestand the result of his study of deformation youas well as Harris finally may come to the result that the sound ppst hold specific condition. Measuring deflection by string load is always better to do fron "ONE" structure instead of sevaral. Already that is important to withhold your undestanding to.

The fact that English is not your mother tongue renders your writing incoherent. Sorry to say. Maybe use Google translate?

 

maybe you should just talk to chatgpt

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3 hours ago, violins88 said:

The fact that English is not your mother tongue renders your writing incoherent. Sorry to say.

yeah - but on the other hand Reguz has done a pretty good job of stirring up a discussion.  Kinda hate to see him take so much heat (an American idiom, Jacob - it means to receive a lot of verbal abuse), barmy (oooops) and incorrigible or not.

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All of you are correct. Dutch and Swedish are my languages. So, expressing in this special item is not easy.

However, I expect on the otherhood that most of you are able understanding the many figures you find on my internet site that explain fact quite well.  My opinion is that the sound post hold very special function in deformation condition by stress load contra what some scientist always show. I believe it is simple understanding. N Harris almost did it right. He measured from bolls on the widest bouts. Cross over there is an axis since he holds the bolds the bolls on a given fix location. What he found was that the end blocks move upward and the center downward in relation to the given fix axis.

But moving that axis closer the center the end block move more upward and the center less downward. Finally, only ONE POINT the sound post is the fix structure that do not move.

N Harris became awarded with a PhD title for this work. I discussed a lot with him and he told me: He was only interested in knowing how the bout shapes deflect. He agreed on my explanation about the function of the sound post

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4 minutes ago, reguz said:

All of you are correct. Dutch and Swedish are my languages. So, expressing in this special item is not easy.

However, I expect on the otherhood that most of you are able understanding the many figures you find on my internet site that explain fact quite well.  My opinion is that the sound post hold very special function in deformation condition by stress load contra what some scientist always show. I believe it is simple understanding. N Harris almost did it right. He measured from bolls on the widest bouts. Cross over there is an axis since he holds the bolds the bolls on a given fix location. What he found was that the end blocks move upward and the center downward in relation to the given fix axis.

But moving that axis closer the center the end block move more upward and the center less downward. Finally, only ONE POINT the sound post is the fix structure that do not move.

N Harris became awarded with a PhD title for this work. I discussed a lot with him and he told me: He was only interested in knowing how the bout shapes deflect. He agreed on my explanation about the function of the sound post

IMHO, choosing your fixed point of reference is nothing more than a convenience to simplify the math, along with choosing your coordinate system.  In reality, nothing's really been "at rest" since the Big Bang, and in higher dimensions, perhaps not even then.  :)

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5 hours ago, Peter K-G said:

That's a bold statement

Other to think about very important is why must we have spruce wood. My undestanding comes from my structural shape conditions. We have a nice framework. The many wintergrown wood beams hold on one side fix condition and on the other end pinned condition. So we may expect since the STLs do not deflect that thegice resistant. The condition we find is tha we have many diffrent lenght on the boey beams with sifter wood in between. Sevaral together may hold a certain bending stiffness that vcan be related to stiffness related to MODE condition. So the many together may respond on a played frequency. I have tested this by polishing on the bout shapes and it work quite well.

 

2 minutes ago, David Burgess said:

It ain't been easy. Had to make a special effort. :lol:

No of course no by you do your very best. Hope you are successful also in that beside you violin making. I have seen your nice violin in Cremona. Great work David!!

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48 minutes ago, Violadamore said:

IMHO, choosing your fixed point of reference is nothing more than a convenience to simplify the math, along with choosing your coordinate system.  In reality, nothing's really been "at rest" since the Big Bang, and in higher dimensions, perhaps not even then.  :)

It is a pity that you do not understand the vector diagram and the consequence what N Harris did

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1 hour ago, reguz said:

But moving that axis closer the center the end block move more upward and the center less downward. Finally, only ONE POINT the sound post is the fix structure that do not move.

It's hardly of interest to me to repeat my earlier statement.

I'm getting suspicious that your English and typing may be better than you let on, you may understand the content of discussions you provoke, and that you're actually a practiced and accomplished chain-puller.  If so, my hat's off to you - your art is admirable.

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1 hour ago, reguz said:

All of you are correct. Dutch and Swedish are my languages. So, expressing in this special item is not easy.

However, I expect on the otherhood that most of you are able understanding the many figures you find on my internet site that explain fact quite well.  My opinion is that the sound post hold very special function in deformation condition by stress load contra what some scientist always show. I believe it is simple understanding. N Harris almost did it right. He measured from bolls on the widest bouts. Cross over there is an axis since he holds the bolds the bolls on a given fix location. What he found was that the end blocks move upward and the center downward in relation to the given fix axis.

But moving that axis closer the center the end block move more upward and the center less downward. Finally, only ONE POINT the sound post is the fix structure that do not move.

N Harris became awarded with a PhD title for this work. I discussed a lot with him and he told me: He was only interested in knowing how the bout shapes deflect. He agreed on my explanation about the function of the sound post

Your emphatic claim that the sound post is fixed is a fixation.

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1 hour ago, reguz said:

It is a pity that you do not understand the vector diagram and the consequence what N Harris did

It's a pity that you wouldn't know a vector matrix from Alpha Bits, particularly as you posted a copy of Tunlid and Värelä, who obviously do.   :P  :P

  [Begins filling her Bag of Pejoratives with things she has to handle with long tongs.]  :lol:

popcorn-and-drink-smiley-emoticon.gif.33be23e1cadd9ea2cda1d9ee12ef1b66.gif

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22 minutes ago, Marty Kasprzyk said:

Your emphatic claim that the sound post is fixed is a fixation.

Since the complete instrument is movable the sound post also is. But making FEA calculations give the sound post this function instead of what scientist do give the end block fixed location otherwise they cannot make their calculations.

With the sound post given the fix condition you may hold that structural part in any direction when you make your FEA calculations the result is always correct. 

So, you cannot do with the end blocks since they are fixed to each other. They do not move in relation to each other.

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