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Long Arch Drawing


Dennis J
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9 hours ago, reguz said:

VSA Stoppani.docx 134.42 kB · 11 downloads For a long time, I have tried to make it for you understandable how string load act on the instrument. You all know my point of view that it is the end blocks that move in relation to the soundpost. I have also discussed this with C Gough and G Stopping. Today my eyes came on the video from the Acoustic seminar with G Stopping. I ask you all to take a good look on what the video images show. The end blocks are in fixed position while the bridge/sound post and almost all structure on the instrument move relocate in relation to the end blocks. After you once again study what the vector diagram shows now look at this video, I hope you understand that Stopping is completely wrong when he shows something that is impossible producing on any violin. Still, this is what the VSA and their many violin makers are learned understanding.

One's frame of reference is irrelevant in the explanation of a physical phenomenon. Any correct analysis including vector analysis will come to the same answer regardless of the frame of reference if done properly. Do the blocks move or does the sound post move? Both are true and the language depends on the frame of reference and the coordinate system coming from that frame of reference. To say that one frame of reference is the only correct one any everyone else is wrong is incorrect and anyone who has had any engineering training knows that. One usually chooses a reference point and frame of reference that simplifies the analysis and makes the math easier to work with. 

Edited by Greg Sigworth
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1 hour ago, Greg Sigworth said:

One's frame of reference is irrelevant in the explanation of a physical phenomenon. Any correct analysis including vector analysis will come to the same answer regardless of the frame of reference if done properly. Do the blocks move or does the sound post move? Both are true and the language depends on the frame of reference and the coordinate system coming from that frame of reference. To say that one frame of reference is the only correct one any everyone else is wrong is incorrect and anyone who has had any engineering training knows that. One usually chooses a reference point and frame of reference that simplifies the analysis and makes the math easier to work with. 

Am I watching a sun set or an earth rise?

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7 hours ago, reguz said:

Dear Dr. Mark it is vey sad. I suffer from dyslexia and use a spelling program that transform some times words. It also happened with Hugo. I appoligy.

No need, thank you.

 

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Dear Greg You seem to forget that there are corces acting on the instrumnent. No forces and you cann take any point you like as a referens point describing is structure but you cannot when forces act and you muste describe the equilibrium state related to acting force. If you have another solution as I have shown so please do that.

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10 hours ago, Marty Kasprzyk said:

Am I watching a sun set or an earth rise?

You're observing dual rotational motion from a fixed point of observation that can change reference points....man

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2 hours ago, jezzupe said:

You're observing dual rotational motion from a fixed point of observation that can change reference points....man

Dear jezzupe, We are talking abouit the function of the violin not moving somewere in space. I'm talking about how the violion structure deflect by strung load. String load act on the end blocks and have a downward resultant forde on the bridge. Not making conditions to complex I show the bridge/sound post in line and the vectors show how equilibrium arises. Question do you understand the vector diagram?

David Burgess say; Show you one what? I won't be removing my pants until later tonight, if at all.. He say I'm wrong but cannot come wit any proof. 

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On 4/30/2022 at 2:52 AM, Michael Darnton said:

For me, the starting point is the humility to admit that the Cremonese makers actually knew something

I wouldn’t say ‘that they knew something’. They systematically worked in one direction of an imagined tonal goal just empirically without knowing. In a certain way this is by far better than ‘knowing’, because it is born and governed by experience. And it certainly doesn’t diminish their achievements.

 

On 4/30/2022 at 2:52 AM, Michael Darnton said:

If one persists in imagining that they weren't that good and modern is better, or that you can be smarter than they were without even knowing what they did,  well, that's a dead end.

It is surely a mistake to ignore or deny achievements of other makers with the goal to make your own stuff look better. However, I am not convinced any more that the Cremonese construction system as a whole is the only answer to build instruments which raise the adrenaline level of high class performers. 
 

Concerning the long arch shape of the back, not only Cremonese makers used a circle. I made a copy of Leopold Widhalm decades ago which had a almost perfect circle shape for the long arch. (Much closer than your pictured example) I am sure you can track this pattern on many other non-Cremonese instruments as well. (though I have no direct proof for it at hand.)
On your picture i find it rather interesting THAT the arching shows a LOCAL deformation. Warping in local areas which are not in spots were direct forces attack the structure are not likely to develop even over a very long time span. When flames of the wood cause a ‘deformation’ you can observe it as a wavy pattern all over the back and never in a narrow zone. Therefore I suspect rather that the wood was intentionally wetted in the construction process and at a point when it wasn’t possible any more to correct it by taking away material. (Or makers weren’t really worried about such ‘imperfections’) 

Just my personal ideas about using patterns is that patterns are useful guides but never in the sense that they must be obeyed in chalk fitted precision. I would leave it to everyone’s personal speculation how precise makers in Cremona followed their theoretic ideas. 

 

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On 5/1/2022 at 12:37 AM, Peter K-G said:

I like this illustration, because you can imagen how it looks like

May I ask what this demonstrates? If this is the stress under tension I would expect anything but a symmetric pattern. 

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One method of seeing the location of high stresses in a part is to varnish the part with a brittle coating (Stresscoat and others, US patent US3801340A is an example) which would crack and craze at the high stressed areas.  Sometimes those areas would be made thicker to reduce the stress while the untracked low stress areas were made thinner to reduce the part's weight.  This might help to improve violin designs.

Sometimes these coatings were made from zinc and or calcium roseate which are apparently quite brittle and they a mixed with small amounts of plasticizers to adjust the amount of deformation they had before they cracked.

I'm guessing that the original violin varnishes used natural rosins that were too brittle in their pure state and that various oils were added in larger amounts to prevent any cracking.

 

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5 hours ago, reguz said:

Dear jezzupe, We are talking abouit the function of the violin not moving somewere in space.

If violins were moving around in space, would that be a problem?  Violas, maybe. Might unbalanced violin forces be a possible inter-stellar propulsion system? :lol:

 

5 hours ago, reguz said:

String load act on the end blocks and have a downward resultant forde on the bridge.

String loads act on all parts of the violin, except possibly parts of the scroll beyond the A peg. Even these will change position, relative to other parts of the violin.

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13 minutes ago, David Burgess said:

If violins were moving around in space, would that be a problem?  Violas, maybe. Might unbalanced violin forces be a possible inter-stellar propulsion system? :lol:

 

String loads act on all parts of the violin, except possibly parts of the scroll beyond the A peg. Even these will change position, relative to other parts of the violin.

With "act on" means the location where the action of the load start its action. When this happens the instrument start deflecting and just as you correctly say this will change position, relative to other parts of the violin, thus static deflection. 

String load act on the end blocks and produce action on the bridge. Primary we thus have 3 points on which we find action. TWO inward/upward at the end blocks and ONE downward on the bridge. These are the forces shown as the main vector forces shown on the vector diagram that only show forces acting on the violin body. But of cource the neck etc also are affected.

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6 hours ago, reguz said:

David Burgess say; Show you one what? I won't be removing my pants until later tonight, if at all.. He say I'm wrong but cannot come wit any proof. 

What you are most wrong about is that only your perspective or frame of reference is the "right" one. You have been offered different perspectives multiple times, but stubbornly refuse to accept them, or apparently, even read or make any attempt to understand them.

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21 minutes ago, reguz said:

String load act on the end blocks and produce action on the bridge. Primary we thus have 3 points on which we find action. TWO inward/upward at the end blocks and ONE downward on the bridge.

With that, you are starting to show some signs of at least beginning to "get it". :)

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5 hours ago, Marty Kasprzyk said:

Sometimes those areas would be made thicker to reduce the stress while the untracked low stress areas were made thinner to reduce the part's weight.  This might help to improve violin designs.

 

Biggest stress area is at the top block through the leverage of the neck. (You can literally see it when you string up an instrument without the back plate) Though the experiment of an absolute stiffening reinforcement in this area brought a slight improvement for the sound of the new concept violin, it wasn’t the best ‘trick’ of the construction. But overall it was one of the tricks to reduce the overall weight beyond a threshold of minimum weight in the classic construction (Somewhere around 360-370g)
 

However it seems that an extremely stiff rib construction different from the classic construction is a good starting point for many things which follow. I see the main advantage in that the top plate can be made thinner than with conventional ribs. 

In reference to the main topic of this thread I believe now that the long arch of the top plays in fact a major role for how a violin sounds in the end. But I have slight doubts that a precalculated long arch pattern is the best solution to get the maximum out of it. With ‘maximum’ I mean a measurable sound level of high frequencies between 2khz and 4khz. Those are the frequencies which have most impact on the general sound color of a violin and also seem to be a necessary ingredient for sound projection.  

Note: extremely thin ribs are definitely THE recipe to kill the sound of a violin. For violas this seems to be different. 

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What

On 5/1/2022 at 4:55 PM, Greg Sigworth said:

One's frame of reference is irrelevant in the explanation of a physical phenomenon. Any correct analysis including vector analysis will come to the same answer regardless of the frame of reference if done properly.

he

16 hours ago, reguz said:

Dear Greg You seem to forget that there are corces acting on the instrumnent. No forces and you cann take any point you like as a referens point describing is structure but you cannot when forces act and you muste describe the equilibrium state related to acting force.

says.

No, Greg is absolutely correct.  It's a fundamental principle underpinning all of physics since Newton, and verified by centuries of experiment that won't be changed by your or my opinions.  In your pictures for Greg you've chosen a stationary frame in which you display your images.  If you describe the motion in this frame, or whether you attach the origin of your reference frame to a block, or to the soundpost, or to Rudolph the Red Nosed Reindeer's liver,  whether your chosen frame is Euclidean or twisted like a corkscrew the violin is going to move the same way in response to the forces acting on it.  The equations of motion, written in the chosen frame of reference, will correctly describe the violin's motion.  I don't mean to dissuade you from questioning anything you like, in fact I encourage it, but some basic text such as Haliday and Resnick would probably serve you better.  Even this post doesn't really belong here, but I'm a bit of a curmudgeon about my own field.

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25 minutes ago, Dr. Mark said:

What

he

says.

No, Greg is absolutely correct.  It's a fundamental principle underpinning all of physics since Newton, and verified by centuries of experiment that won't be changed by your or my opinions.  In your pictures for Greg you've chosen a stationary frame in which you display your images.  If you describe the motion in this frame, or whether you attach the origin of your reference frame to a block, or to the soundpost, or to Rudolph the Red Nosed Reindeer's liver,  whether your chosen frame is Euclidean or twisted like a corkscrew the violin is going to move the same way in response to the forces acting on it.  The equations of motion, written in the chosen frame of reference, will correctly describe the violin's motion.  I don't mean to dissuade you from questioning anything you like, in fact I encourage it, but some basic text such as Haliday and Resnick would probably serve you better.  Even this post doesn't really belong here, but I'm a bit of a curmudgeon about my own field.

My then new Haliday and Resnick physics textbooks were copyrighted in 1960.  

Sort of sobering.

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The idea of strengthening the mid section of the violin body makes a lot of sense to me. Apart from thicker C-bout ribs edge thickness should be increased between the corners.

DSC_0002 2.jpg

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All ya gotsta do is straddle a cello like Slim Pickens did in Strangelove and then just take yer two hands and start tightening and loosening pegs and that'l start them blocks a flappin' and den you can fly across this here universe...It's a work in progress. :rolleyes:

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1 hour ago, Dennis J said:

The idea of strengthening the mid section of the violin body makes a lot of sense to me. Apart from thicker C-bout ribs edge thickness should be increased between the corners.

DSC_0002 2.jpg

Well while we're at it why don't we tune down a 1/2 step back to 432/5 like it was most likely for the first 200 years or so of it's life? I have still yet to hear a good explanation as to why it was changed to 440 and how that could possibly be good for an instrument made of 2 thin wooden shells, particularly after 2 or 3 hundred years. I mean hey lets just tune up another 8 cents to 448, that should be good for thin wooden shells.

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1 hour ago, Dennis J said:

The idea of strengthening the mid section of the violin body makes a lot of sense to me. Apart from thicker C-bout ribs edge thickness should be increased between the corners.

DSC_0002 2.jpg

Why do you think/assune that an idea that just occurs to you as reasonable seeming is automatically going to be better than results of generations Cremona families actually testing out to find what truly does work better?

The Cremonese did not end up accepting an idea of generally stronger through the center.  Instep, the settle on strength in sides and corners and near the edges through the cBout area.  And generally, the plate cBout areas present a contrast to this, especially the tops.

The violin we received from peak Cremona is informed not speculative ideas, but by generations of continous testing of small differences, seeing which ones looked or sounded better, or both, across dozens of hands and actually thousands of instruments.  

That is a very powerful discovery mechanism, and it ran for almost 200 years to get to the Cremona peak.

 

The results from organic community development of the violin gave us an instrument that works very very well already, and where almost every detail effectives the whole in multiple complex ways.

Since that time, we've had many individuals come up with bright ideas to improve violins in one way or another, but 'ideas' tend to be one dimensional compared to the development that was already achieved.  

Other than making less expensive and less good violins, such innovation with ideas has failed to improve on what Cremona achieved wholistically through massive and long continued trail and error.

 

So Dennis has invented an arching scheme that seems beautiful and sensible to him.  No one really cares.   Because we know the Cremonese already had their own very succesful schemes of arching, that were tested for 2 centuries in their development, and tested in very successful use for another 3 centuries since then.

What do we care about any 1 year old or even 50 year old scheme of arching that by comparison as barely been tested at all, and by comparison has barely succeeded at all??

 

You make any part thicker, or stronger, or thinner, or weaker, or lighter, or heavier; the consequences are going to be broader and more complicated than the one thing that motivated your change.

Reguz, we don't care that 'you know' and 'have proved' that the soundpost is stationary.   Nor that you've observed STLs.    

 

The violin is not so much about ideas and innovative approaches.   It's a very traditional art object/tool, used in a very traditional musical art.  The most traditional versions of the violin remain the most favored, and the most valued.

 

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I've been thinking about violin structure on and off for about 12 years. I've spent a lot of time formulating what I think and I'm quite confident about where I'm at now.

Of all the posting I've done I can't recall anyone pointing out where my arching or arching method is wrong or even differs from Cremona work. Just vague comments about it's not how they did it. And nobody knows that.

An arch is an arch, it's just a matter of how well you can handle its creation.

Making plate edges thicker in the C-bouts is not just something I've thought about on the spur of the moment, it's a feature of some instruments. If nothing else it enhances the look of an instrument.

I don't see anything about what I've posted as inconsistent with traditional violin making.

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