Is this arching wrong ?

[Anders Buen]

11 hours ago, Peter K-G said:

I would use GIMP

Thanks! :-)

[Anders Buen]

.

Edited December 17, 2023 by Anders Buen
Double post

[Anders Buen]

55 minutes ago, reguz said:

Look at the Terry Borman animation. Count down the shown movements  with a factor 100. What remain on the end blocks. Look at Martin Schleske showing how he measure frequency movement. This shows how Stoppani works and show movement on violin structure related to fix support 

Maestro 3.docx 663.11 kB · 2 downloads

These measurements are done with a 2D system and 1D (single degree) transducers. You only have one third of the picture here. George Stoppani works on a system to use 3D (tri axis) accelerometers. This far only the Polytec Strad 3D measurements works on the full 3D movement, besides the TV-Holographic tests where they can get 3D, using mirrors. 

[Dr. Mark]

From the Strad3d modal images I can see where the idea of a stationary sound post may have arisen.  Those 'Breathing' mode illustrations explicitly showing the post are hand-drawn however, and its behavior appears more than a bit funky.

[reguz]

Professor G Bissinger is probably the person who has done the most research and his list of published articles is very long.

When you refer to what he accomplished in collaboration with Strad 3D is extensive.

But the question is in what way the result what he does is different what Stoppani and Gough do?

What I mean is that the strings are not involved when sound is being produced.

No one, including Bissinger, uses the strings to produce sound and measure the result.

There is no underlying dynamic movement produced that attacks the various parts of the violin body that will produce the sound included.

It takes place in a violin whose arching constantly bends and acquires a state of tension that changes continuously.

The arching that initially becomes active through string tension acts as a spring when the string load varies as the instrument is played.

None of this happens in the surveys that I have seen so far.

With great respect for what Bissinger accomplishes, I unfortunately have to say that they miss probably the most essential thing, which is the functional dynamic state of the strings, which directly affects which frequency modes will be created on different arching sections.

Bissingar with what he does misses the dynamic state completely.

I fully accept the results of what he does but against the above his presentation lacks what is necessary for violin builders to be able to improve results completely.

It is of course possible that you disagree with me but these are the facts I am referring to.

Only when an examination is made of the varying string tension by playing with the bow do we gain an understanding of how everything works.

My own examination of a geometrically constructed violin contains such peculiar features that at least I expect that in a dynamic examination of the same we shall obtain answers so as to be of use to violin makers. It is possible that you do not agree with me, but I have tried to explain the importance of how certain constructive properties affect the stress build-up and shape change. Instruments become shorter and wider in a dynamic state. The arching of the belly and back increases/decreases and creates a change in volume which thus creates a breathing state. These properties are nowhere previously described. What remains for me to do is a special investigation. It is required that at least five instruments built with that design language are included to get a verifiable result. It is required that the instruments be attacked with strings and thus a "string machine" must be manufactured. Soon these violins will be ready and hopefully next year such an examination can be carried out.

[David Burgess]

2 hours ago, reguz said:

No one, including Bissinger, uses the strings to produce sound and measure the result.

Wrong! Measurements of violin sound, using bow excitation of the strings, have been going on for decades. Try to keep up.

[Dave Slight]

2 hours ago, reguz said:

Professor G Bissinger is probably the person who has done the most research and his list of published articles is very long.

When you refer to what he accomplished in collaboration with Strad 3D is extensive.

But the question is in what way the result what he does is different what Stoppani and Gough do?

What I mean is that the strings are not involved when sound is being produced.

No one, including Bissinger, uses the strings to produce sound and measure the result.

There is no underlying dynamic movement produced that attacks the various parts of the violin body that will produce the sound included.

It takes place in a violin whose arching constantly bends and acquires a state of tension that changes continuously.

The arching that initially becomes active through string tension acts as a spring when the string load varies as the instrument is played.

None of this happens in the surveys that I have seen so far.

With great respect for what Bissinger accomplishes, I unfortunately have to say that they miss probably the most essential thing, which is the functional dynamic state of the strings, which directly affects which frequency modes will be created on different arching sections.

Bissingar with what he does misses the dynamic state completely.

I fully accept the results of what he does but against the above his presentation lacks what is necessary for violin builders to be able to improve results completely.

It is of course possible that you disagree with me but these are the facts I am referring to.

Only when an examination is made of the varying string tension by playing with the bow do we gain an understanding of how everything works.

My own examination of a geometrically constructed violin contains such peculiar features that at least I expect that in a dynamic examination of the same we shall obtain answers so as to be of use to violin makers. It is possible that you do not agree with me, but I have tried to explain the importance of how certain constructive properties affect the stress build-up and shape change. Instruments become shorter and wider in a dynamic state. The arching of the belly and back increases/decreases and creates a change in volume which thus creates a breathing state. These properties are nowhere previously described. What remains for me to do is a special investigation. It is required that at least five instruments built with that design language are included to get a verifiable result. It is required that the instruments be attacked with strings and thus a "string machine" must be manufactured. Soon these violins will be ready and hopefully next year such an examination can be carried out.

I think if you alternated the text colour, with red for one paragraph, and green for the next, it would have felt a lot more Christmassy.

[Don Noon]

3 hours ago, reguz said:

My own examination of a geometrically constructed violin contains such peculiar features that at least I expect that in a dynamic examination of the same we shall obtain answers so as to be of use to violin makers.

Verify your expectations and THEN get back to us.  As of now, it is useless except for generating a dozen pages of yammering.  Again.

And my expectation is that when you actually get around to the "dynamic examination", you will find nothing that you expect.  Why haven't you done anything on this in the nearly 9 years since we first started getting inundated with your static theories?

[ctanzio]

Some observations from someone who spent years engineering the vibration of structures, with both computer models and heavily instrumented shake-table testing.

Static loads have some theoretical influence on the vibration of plates that can be observed in real testing. But in terms of the violin, the influences from string tension are so small as to be meaningless. The reason is that the violin arching must be of sufficient shape and thickness to keep static stress low enough to prevent buckling and creep, because a broken violin does not sound too good.

Deflection diagrams and animations can lead to a mythical river where red herrings swim. It is possible to pick an arbitrary point of reference and show all deflections relative to that point. Unless that point is a true stationary point in how the structure interacts with the surroundings, it tells you little about the meanings of any specific points of deflection.

That said, the boundary conditions used to test deflection of a violin, static or dynamic, are important. For example, I see SOME measurable differences in spectral response diagrams between suspending a violin by its volute and holding the violin by the neck while it rests in playing position upon my shoulder. But the differences are too subtle to lead me to any Ah Ha! moments.

 

 

[Anders Buen]

I wonder of we could have a "name dropping contest" here? I know David B most liekely will win, through his volunteering for the VSA Oberlin Violin Making and Repair Workshops, as well as been a long time in the violin repair and making business.

[David Burgess]

It's been a privilege to have had the opportunity to actually hang out with and have discussions with so many of these people over the years. I used to have breakfast with Bissinger every day at Oberlin. He was very good at putting things into easy-to-understand basic mechanical physics language, when he wanted to.

Earlier in the thread, Reguz mentioned Francesco Toto. I co-judged with him at the Moscow Competition, where we spent a lot of time together.

Maybe 40 years ago, Norfleet and I visited Pickering's workshop on Long Island. One of the things he showed us were some bowing machines he had made, in an effort get past the variability of human bow strokes, in order to get more consistent and repeatable results from string excitation with a bow. I offer that as just one more piece of evidence that when Reguz makes claims like, "No one, including Bissinger, uses the strings to produce sound and measure the result", he doesn't have the slightest idea what he is talking about!

[fscotte]

I stated this before and I'll stated again, if it's vibrating it is moving.

Maybe I have no clue what this thread is about, but there isn't a single part of the violin that doesn't vibrate.

[Peter K-G]

Yeah, if it’s raining you will get wet (except if you are under an umbrella)

[Peter K-G]

I’m going back to the simple questions. Viewpoints aside.

Robert, is it your claim that the endblocks are not turning inwards
 

[reguz]

Peter, Do you  need to ask? Can't you see the and undestand the figures?

[Peter K-G]

45 minutes ago, reguz said:

Peter, Do you  need to ask? Can't you see the and undestand the figures?

Of course I can understand the figures!

To get somewhere, there has to be a verbal confirmation back and forth.

So again, simple yes/no question:

Is it your opinion that the endblocks don't turn inwards?

[reguz]

To make may my opinion clear. What you see on the the figure 25 is what I believe happen by string load in static condition. I have studied this carefully and asked my selves how could it be that N Harris found what is shown on figure 27? That's why I show the figure!! I discussed this with Harris and we never came to a confirmed solution. It could be that it is just what his violin did. If string load act mainly upward we can say we have a rotation in relation to the sound post. This is what the figure shows. In that case there only arises a vertical movement that bend the back and buckles the belly.

When I tested varnish removing on both belly and back in order to find out sound improvement I also did probably some stupid. I removed wood in the neck heal. Only very little. The complete sound result became different and very back. What happens? Yes, the neck rotates on the neck heal and do not act longer as is is shown the perfect what happens in figure 25. The deflecting of the buckling belly became affected. I had to do all over removing varnish on the belly bout shape and could get back the best result before scarping in the neck heal. This taught me a lot. So, choosing neck wood and how the wood is grown in horizontal layers is important. If they are not the possible result can be as figure 27 shows. One side become pulling the back more the other. This is still not totally understood by me. I have seen that some maker mounted a dowel inside the neck heal but I believe this was on a Cello. The other problems arise, cracking which show the movement of force acting on the neck heal.

[reguz]

Peter. I earlier gave another possible explanation. If the wood thickness in the center bout on the back is less thick the location of the sound post than by the moment of force on the end block the thinner wood in the center bout will become forced upward and the chord lien in length direction become longer which may result in lengthening s shown on figure 27. Also dis we discussed.

[martin swan]

There seems to be a long-standing amateur fascination with scraping away wood in order to observe sound modifications.

I never heard of such people experimenting with adding mass or stiffness. I assume this is because it’s much harder to do … 

[David Burgess]

1 hour ago, martin swan said:

There seems to be a long-standing amateur fascination with scraping away wood in order to observe sound modifications.

I never heard of such people experimenting with adding mass or stiffness. I assume this is because it’s much harder to do … 

"I cut and cut, and it's still too small."

[LCF]

On 12/19/2023 at 12:19 AM, Dave Slight said:

I think if you alternated the text colour, with red for one paragraph, and green for the next, it would have felt a lot more Christmassy.

I know, I promised, but this is more of a supportive administrative comment. Red, green, and white as the snow, as white as holly berries, as white as noise.  A white font on a white background would be very cheery. 

Like this:

[Anders Buen]

13 hours ago, martin swan said:

There seems to be a long-standing amateur fascination with scraping away wood in order to observe sound modifications.

I never heard of such people experimenting with adding mass or stiffness. I assume this is because it’s much harder to do … 

There are patches in the back plates of many instruments after grandpa. The end regions of the top also can have rather thick patches.

Edited December 20, 2023 by Anders Buen
Info on tops

[Anders Buen]

18 hours ago, reguz said:

To make may my opinion clear. What you see on the the figure 25 is what I believe happen by string load in static condition. I have studied this carefully and asked my selves how could it be that N Harris found what is shown on figure 27? That's why I show the figure!! I discussed this with Harris and we never came to a confirmed solution. It could be that it is just what his violin did. If string load act mainly upward we can say we have a rotation in relation to the sound post. This is what the figure shows. In that case there only arises a vertical movement that bend the back and buckles the belly.

When I tested varnish removing on both belly and back in order to find out sound improvement I also did probably some stupid. I removed wood in the neck heal. Only very little. The complete sound result became different and very back. What happens? Yes, the neck rotates on the neck heal and do not act longer as is is shown the perfect what happens in figure 25. The deflecting of the buckling belly became affected. I had to do all over removing varnish on the belly bout shape and could get back the best result before scarping in the neck heal. This taught me a lot. So, choosing neck wood and how the wood is grown in horizontal layers is important. If they are not the possible result can be as figure 27 shows. One side become pulling the back more the other. This is still not totally understood by me. I have seen that some maker mounted a dowel inside the neck heal but I believe this was on a Cello. The other problems arise, cracking which show the movement of force acting on the neck heal.

Static thinking and analysis will only be valid for the region below any resonance in the system. You cannot deduce dynamic behavior in the resonance regions of the violin by static reasoning. You got to use dynamics! 

[reguz]

What you say is You do not need to know the shape of the structure and its internal stiffness conditions. Is it this you say?

[Anders Buen]

1 hour ago, reguz said:

What you say is You do not need to know the shape of the structure and its internal stiffness conditions. Is it this you say?

You cant deduce the dynamic response, far above the "DC level", for a vibrating body by assuming it from its static shape and static forces. If you want to see the dynamics, you have to do the dynamics.