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Roger Hill

An incredibly perceptive idea for strong arches............

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3 minutes ago, Marty Kasprzyk said:

I disagree.  The violin's arch is supported by the corner blocks which prevents it from stretching out sideways and collapsing --da Vinci's bridge arch is supported by the bridge abutments that do the same thing.

But only if there were no sound post which prevents that the downward force of the bridge can make the arch cave in. And on the bass side there is anyway the structural reinforcement of the bass bar.

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12 minutes ago, Violadamore said:

He's calling us swine, of course.  :lol:

Very gently criticizing, doesn't anybody see the geometry of that bridge structure as being approximately the shape of the shell of a violin plate?  No one sees the approaches to the bridge as having the same shape of the figure 8 of the top and bottom plates?  That the ridge of the violin arch from lower bout, through c bout and into the upper bout has the same shape as da Vinci shows for his bridge?  Sheesh!

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After reading the article on the MIT research project, I was a bit shocked at the unsophisticated nature of the "testing" and lack of application of known principles for scaling models of structures subjected to settling and earthquake loads. At first I thought it might be due to the editing of a reporter unfamiliar with engineering, but it was published on an MIT web site.

It looks like someone learned how to use a 3D printing program and went in search of something cool to make. Any relation to an actual stone bridge or a violin arch is strictly coincidental.

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13 minutes ago, Roger Hill said:

A biblical reference,  explanation from Wikipedia, not intended for you Marty, or for others who respond in genuine interest in what I thought would be obvious.  I must be wrong about what is obvious, my bad.

What does it mean to cast your pearls before swine?
Do not cast your pearls before swine. Do not waste good things on people who will not appreciate them. This proverb is adapted from a saying of Jesus from the Gospels, “Cast not pearls before swine.” Jesus appears to be warning his disciples to preach only before receptive audiences.

Thanks for the reference and helpful insight.

I'm also having trouble making some good wine for a wedding.

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3 minutes ago, Marty Kasprzyk said:

Thanks for the reference and helpful insight.

I'm also having trouble making some good wine for a wedding.

Can't help with making wine, but starting at about $15.00/bottle you can find plenty of stuff that I like and would enjoy in prudent quantities at any wedding I'll ever attend.  In addition, after about half a bottle, you may find it quite easy to find a violin arch in the shape of the bottle, burgundies in particular..........:D

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9 minutes ago, ctanzio said:

After reading the article on the MIT research project, I was a bit shocked at the unsophisticated nature of the "testing" and lack of application of known principles for scaling models of structures subjected to settling and earthquake loads. At first I thought it might be due to the editing of a reporter unfamiliar with engineering, but it was published on an MIT web site.

It looks like someone learned how to use a 3D printing program and went in search of something cool to make. Any relation to an actual stone bridge or a violin arch is strictly coincidental.

I read somewhere where Roman engineers had to stand underneath the stone arches they designed and had built when the supports were removed to leave the free standing arch.

Perhaps MIT students should have to do something similar.

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33 minutes ago, Roger Hill said:

Very gently criticizing, doesn't anybody see the geometry of that bridge structure as being approximately the shape of the shell of a violin plate?  No one sees the approaches to the bridge as having the same shape of the figure 8 of the top and bottom plates?  That the ridge of the violin arch from lower bout, through c bout and into the upper bout has the same shape as da Vinci shows for his bridge?  Sheesh!

I actually went through some of my photo collection and looked, but feel that the similarities are coincidental.  Some of the ones closest to Da Vinci's curve are trade fiddles.  :)

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8 minutes ago, Roger Hill said:

Can't help with making wine, but starting at about $15.00/bottle you can find plenty of stuff that I like and would enjoy in prudent quantities at any wedding I'll ever attend.  In addition, after about half a bottle, you may find it quite easy to find a violin arch in the shape of the bottle, burgundies in particular..........:D

I agree the graceful sloped inflection shape of a Burgundy bottle is most attractive and its wine's full luscious velvety taste follows this visual image. But can't afford a bottle of old Burgundy and my attempts at making pinot noir were the same as my violin making. 

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9 hours ago, Marty Kasprzyk said:

What does that mean "casting dry flies rather  than pearls...."  I know about casting dry flies.  What about pearls?  

Pearls are what you use as bait, rather than flies, if you want to catch Gold (digger) fish.

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13 hours ago, Violadamore said:

Leonardo's proposal failed to include any information on materials or methods.  The model design is a very free interpretation.  I suspect that providing the removable scaffolding required for a bridge over 900 feet long and around 150 feet high, more than half of which is over water, in 1502, would have been as big a challenge as the bridge structure itself.  I'll also note that, with the mathematics of the time, Leonardo could not have possibly performed the calculations required to get exact numbers for the project.  :)

http://news.mit.edu/2019/leonardo-da-vinci-bridge-test-1010

I thank Da Vinci was probably a great admirer of Brunelleschi's work.

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55 minutes ago, sospiri said:

I thank Da Vinci was probably a great admirer of Brunelleschi's work.

I found this on the internet regarding the building of Brunelleschi's amazing masonry dome in Florence:

 

Another of these crucial elements is the lantern, on top of which rests the bronze ball built by Verrocchio in 1472. To position the ball they used machines invented by Brunelleschi. The young Leonardo da Vinci figured among the apprentices that helped in this difficult operation.

Leonardo da Vinci drawing: winch invented by Brunelleschi

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1 hour ago, Marty Kasprzyk said:

I found this on the internet regarding the building of Brunelleschi's amazing masonry dome in Florence:

 

Another of these crucial elements is the lantern, on top of which rests the bronze ball built by Verrocchio in 1472. To position the ball they used machines invented by Brunelleschi. The young Leonardo da Vinci figured among the apprentices that helped in this difficult operation.

Allegedly

Leonardo may have done some soldering. Some websites claim that he designed the winch that hoisted the ball atop the lantern. But it was designed by Brunelleschi many years before. But he was obviously inspired by the design enough to make those drawings.

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15 hours ago, Marty Kasprzyk said:

I read somewhere where Roman engineers had to stand underneath the stone arches they designed and had built when the supports were removed to leave the free standing arch.

Perhaps MIT students should have to do something similar.

That story appears to be something that C. Michael Armstrong (a long-time IBM executive, later noted for turning post-Cold War Hughes around, and subsequently reinvigorating AT&T, by being godfather of both DirecTV mini-dishes as well as the cable modem) started throwing into motivational speeches, probably while at Hughes in the 1990's.  No earlier source for it seems to exist.  The Latin historical scholarship community rejects it as B.S.  :lol:

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4 hours ago, sospiri said:

I thank Da Vinci was probably a great admirer of Brunelleschi's work.

Yup, but while his drawings of Brunelleschi's innovations are detailed, this bridge design seems to be strictly back-of-the-envelope-or-dinner-napkin, conceptual stuff.  :)

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18 hours ago, Andreas Preuss said:

@roger hill

would be interesting to build it from wood and compare it to other central arch patterns of the top to see how it compares in reality. My rough guess is that eventually material properties play a bigger role than the shape itself.

It looks like a normal circular arch and for me the more important question is how to relate the length of the arch to its height.

However, the big difference in the structure of the violin is that the arch of the top is supported by the sound post. 

That has been done: https://en.m.wikipedia.org/wiki/Vebjørn_Sand_Da_Vinci_Project

 

It should really have been a catenary arc, which is much easier to construct than to calculate: All you need to do is trace the curve if a chain, suspended from both ends. Mr Sand decided to depart from the original drawing so much that I wonder hiw they could call it the da Vinci Project. ;)

From what I have seen violin arcs are rarely catenary and maybe even more rarely circular

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On 10/15/2019 at 7:03 PM, Roger Hill said:

Very gently criticizing, doesn't anybody see the geometry of that bridge structure as being approximately the shape of the shell of a violin plate?

I think EVERYBODY sees that bridges are arched for a reason, and so are violin plates.  Arches have been known and used for thousands of years.  It's not like Leonardo came up with something brilliant or new (in this case).   And almost all violins are not exactly what is done for bridges anyway.  Thus all the nutty tangential posts.

Actually, if you wanted to make the most efficient static structure to support the bridge and string loads, it would NOT be a nice, smooth arch... as the bridge is a point load and should be treated differently.  The arch I think is more for acoustic/vibration reasons, and possibly some aesthetics thrown in.

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On 10/16/2019 at 3:57 AM, David Burgess said:

Pearls are what you use as bait, rather than flies, if you want to catch Gold (digger) fish.

Nah' out here you just use free rent instead :lol:

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3 hours ago, Don Noon said:

I think EVERYBODY sees that bridges are arched for a reason, and so are violin plates.  Arches have been known and used for thousands of years.  It's not like Leonardo came up with something brilliant or new (in this case).   And almost all violins are not exactly what is done for bridges anyway.  Thus all the nutty tangential posts.

.............

Thankfully, they haven't been as nutty, or as numerous, as they might have been, nor as vehement.  Also, just in case others have noticed the same thing I did about a gross misinterpretation of the original drawing that obviously led to the CAD version that inspired the OP question, I feel that a violin forum is the wrong place to put the MIT people in the pillory.  As I said to Julian, let's not.  Anyone so inclined is invited to PM me, we'll have a few giggles.  :)

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On 10/16/2019 at 4:16 PM, Felefar said:

That has been done: https://en.m.wikipedia.org/wiki/Vebjørn_Sand_Da_Vinci_Project

 

It should really have been a catenary arc, which is much easier to construct than to calculate: All you need to do is trace the curve if a chain, suspended from both ends. Mr Sand decided to depart from the original drawing so much that I wonder hiw they could call it the da Vinci Project. ;)

From what I have seen violin arcs are rarely catenary and maybe even more rarely circular

 

11 hours ago, Don Noon said:

I think EVERYBODY sees that bridges are arched for a reason, and so are violin plates.  Arches have been known and used for thousands of years.  It's not like Leonardo came up with something brilliant or new (in this case).   And almost all violins are not exactly what is done for bridges anyway.  Thus all the nutty tangential posts.

Actually, if you wanted to make the most efficient static structure to support the bridge and string loads, it would NOT be a nice, smooth arch... as the bridge is a point load and should be treated differently.  The arch I think is more for acoustic/vibration reasons, and possibly some aesthetics thrown in.

Is a strait slope speaker cone the ideal shape?

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11 hours ago, Marty Kasprzyk said:

Is a strait slope speaker cone the ideal shape?

Yes, if you get rid of the flexible surround.  Again, we're talking about only static support of a point load, where straight lines are most efficient by carrying all load in compression or tension in the material, eliminating bending (which is very inefficient).  Arches are for distributed loads.

Once you demand that the vibration behavior of the plate produce a pleasing sound and work well for the player, the whole thing becomes a compromise and impossible to resolve by any theory.

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Here's the perfect violin structure (in concept) if you want to only think about static loads.  The lower one is modified to put in a neck and end blocks so you could play it and have something for a chinrest to clamp onto.  You'd need two soundposts... one under each bridge foot.  I'll bet it would sound like crap.

1471413232_PerfectViolinStructure.jpg.e34db70698e5967e16f5242c509b120e.jpg

 

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1 hour ago, Don Noon said:

Here's the perfect violin structure (in concept) if you want to only think about static loads.  The lower one is modified to put in a neck and end blocks so you could play it and have something for a chinrest to clamp onto.  You'd need two soundposts... one under each bridge foot.  I'll bet it would sound like crap.

1471413232_PerfectViolinStructure.jpg.e34db70698e5967e16f5242c509b120e.jpg

 

Ya but you could probably win Le'mans with it.

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Hi Don,

I agree that this would minimize static loads and would produce the least amount of deformation and probably not produce much sound output.

Do you think makers hundreds of years ago were using curved arched plates to get the most deformation rather than the least?

 

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