reguz

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  1. reguz

    Why arching shape?

    John answering on the two latest sentenses. I have been testing on an violin made 40 years ago and never touched how stress affect the responce on the accoustic outcome. I did this regarding the function of the frame work. arching shape that become stress by the compression forces on the longitudinal curve on the bout shape changes by reducing the varnisch. In the beginning of this polidhing process I was not able observing quality differences. However the player (I do not play) Staffan Borseman the former concert master of the Denish Radio orchestra Chttps://www.thestrad.com/violinist-and-stringed-instrument-expert-staffan-borseman-has-died-aged-60/5940.article), could hear clear difference by each polishing moment. We worked together seven years. Finally I also could hear the diference. We together made the conclusion that reducing varnisch changes the stress on the bout outside and minor on the inside. Also the location I polished had great influence on the acoustic result. I did this process over and over again. Some times it became real bad, which also shoe that stress is involved. Yes al this is an interresting phusical question. I believe I learned over a period of five years to understand what the quality of my geometric arching influences. Looking at the holograpic pictutre opf the back by slight increasing the d string, very little, we get a map that show where the structure bulge outward. The balck lines are principlaly a hinge. + on one side and - on the other. So what we see is inflection point along the line. On the location of the STL they become strtight and tells us that at that point we have resistant, the frame work. Unfortunatally I'm not enough educated being able to discuss Gaussian curvature inluence on arching shape. This is a total open field in my knowledge.
  2. No Wood, I never heart of him but certainly will look at the internet!! I'm open for any kind of discussion!!
  3. reguz

    Why arching shape?

    Do, You seem to bee of opinion that it does no matter haw the transtion from one curce shape to the next, the next, the next has any influence on the behaior of stress producing condition and with that influence on how the plate may vibrate not paying any atterntion to how to graduate the plate thickness in relation to the arching shape and the wood fiber condition. I state on good ground that the arching shape you find on my interternet is optimal in the transition from the next to the next to the next cross section. Yes stop now because I see you have difficulty understanding
  4. Yes David your observations are right. The technical term you should use for pressure on two ends produce "Buckling" that are forces normally on a column in a building. Since the shape of the longitudinal arc shape hold a curve we know for sure in what direction it will deflect (buckle) this is as you say on the bout shapes. On the "island" the bridge feet stay in front of the sound post. The bridge will produce e downward bending of the structure between the sound post and the cross structure between the upper F-hole eyes. That also is the local structure the STLs end on the top of the arching shape, thus a firmly stable structure. Beside that it’s the location of the less wide cross section in the C-bout. All these work together making the firmly stable structure. Putting in the sound post and string up produces forces on the violin structure I earlier showed with a vector diagram. Compression forces arises on the sound post. Depending on the angle of the string over the bridge a specific compression becomes produced. The total system in in a state of equilibrium, it do not move at any direction. However a lot of energy is transformed into the violin body. When the structure hold a specific stiffness the transformed string load is spread out over the bout shapes thus getting bulging stress condition like blowing a balloon. When that happens the structure becomes sensitive for any change in the applied stress system, thus changing string load by the playing action. No about what you say about the highest point on the tremble side. When you pull the strings you pull the complete back plate upward with the sound post as the supporting withstanding structure. However, structure surrounding the sound post location are not supported and thus move upward, are part of the bending process that is going on. If the sound post was placed on the center line the surrounding structure would deflect symmetrical measured from the sound post. We have a different location and thus the surrounding structure do not deflect symmetrical as we graduate the thickness of the plate. We can prevent by making the location on the other side of the center line stiffer. This means make it thicker. When you stay on a board out of the center like the sound post and start pulling you will find the the length curves not are symmetrical. You need an extra support = extra sound post to be able making them curve to become equal. Please take a close look at the vector diagram I have showed before. Equilibrium state arises when the sum of the upward force under the bridge by compression on the end blocks together with the upward forces on the end blocks make the zero state. In between the buckling and bending bout shapes. Hope this will give you a better understanding Yes David your observations are right. The technical term you should use for pressure on two ends produce "Buckling" that are forces normally on a column in a building. Since the shape of the longitudinal arc shape hold a curve we know for sure in what direction it will deflect (buckle) this is as you say on the bout shapes. On the "island" the bridge feet stay in front of the sound post. The bridge will produce e downward bending of the structure between the sound post and the cross structure between the upper F-hole eyes. That also is the local structure the STLs end on the top of the arching shape, thus a firmly stable structure. Beside that it’s the location of the less wide cross section in the C-bout. All these work together making the firmly stable structure. Putting in the sound post and string up produces forces on the violin structure I earlier showed with a vector diagram. Compression forces arises on the sound post. Depending on the angle of the string over the bridge a specific compression becomes produced. The total system in in a state of equilibrium, it do not move at any direction. However a lot of energy is transformed into the violin body. When the structure hold a specific stiffness the transformed string load is spread out over the bout shapes thus getting bulging stress condition like blowing a balloon. When that happens the structure becomes sensitive for any change in the applied stress system, thus changing string load by the playing action. No about what you say about the highest point on the tremble side. When you pull the strings you pull the complete back plate upward with the sound post as the supporting withstanding structure. However, structure surrounding the sound post location are not supported and thus move upward, are part of the bending process that is going on. If the sound post was placed on the center line the surrounding structure would deflect symmetrical measured from the sound post. We have a different location and thus the surrounding structure do not deflect symmetrical as we graduate the thickness of the plate. We can prevent by making the location on the other side of the center line stiffer. This means make it thicker. When you stay on a board out of the center like the sound post and start pulling you will find the the length curves not are symmetrical. You need an extra support = extra sound post to be able making them curve to become equal. Please take a close look at the vector diagram I have showed before. Equilibrium state arises when the sum of the upward force under the bridge by compression on the end blocks together with the upward forces on the end blocks make the zero state. In between the buckling and bending bout shapes. Hope this will give you a better understanding
  5. Yes, repeating the shape of the arching is nesasarry in order to find out
  6. reguz

    Why arching shape?

    All right Bill I will let you know my opinion whay we need archong shape. When string load start deflecting the instrument the belly become buckled and stress conditions arise on many different curve shape. A string at pitch produces a specific frequencyu. A bend curve shape also can vibrate with a specific frequency. When we have many curve shapes we can assume we mustr accept that they can vibrate at meny differnt frequency. A flat plate donnot hold this quelity. So my opinion is tha arching shape provide special quality a flat structure does not have.
  7. David. You say the back is going down by the action of the sound post. My opinion is tha the end block pull upp teh arching and a moment of force over the soundpost become produced. If the thickness= stiffness under the sound post is not strong enough that location will bend more than the arc shape on the bout. In fact on some violins you can observe a local bulging. Thus thsi is not what you believe its the other way around.
  8. reguz

    Why arching shape?

    Yes Jezzupe, the load of the piano will produce a moment of force in downward direction and when the plywood is not thick enough it will crack. On the violin we have a load almost on the sound post and and still there is no movemet downward to measure. What forces do produre equilibrium Jezzeppe? On the floor with the piano the walls are supporting remain on the same level. On the violin the sound post remain on the same level. Try to undrstand that. No force is cominhg out under the sound post producing a downward force. You may explain the contrarry if you can!!!
  9. Dear Mad, I'm but once again I must give the same answer as I have given so many times before and still is not understood. What I say is the arching shape does not collapse by the load on the bridge. The reason the bridge is so close the sound post the only structure on the violin that do not move by increasing string load. The sound post is principally the center of ratationof all surraunding structure. Once again test what I write Stay on a scale (in your bathroom) with a plöank under your feet (say 3m) and fit a rope on the plank ends. Take the rope in your hand astart pulling while you at the sam,e time observe what happens on the scale. NOTHING. What happens is that the plank on both side start bending due to the moment of force. Equal condition on the violin but there we have different lenght that produce the moment of force and also different structure and stiffness. We cannot expext that the stress conditions that arise on thelower and upper bout are equel. This means that they cannot react equal when a string is played. Ajustment is needed and you can do this by moving the sound post along the lenght axis. You try to find out the best position but still there is more to do. If your plate are to this you like to have less outward bulding (=stress condition). This you adjust by moving the sound post sideward. The basic figure the isoscale trapeziod with the two basis, sound post and end block, do not schange but thelegs will change. Since the curve on the leg of the trape... alway remain with its lenght the chordline underneath must do and that make the curve less or more wich produce different stress on the bout shape. The curve simply move up or down. This will change sound quality since the produced sound depend on stress as it is with the stress on the string by moving your finger. What prevent collapsing is the STL fram-work. That structure do not deflect but the outside STL must have ainside STL underneath other vise the center line in order to be straight must allow deflection. That we must prevent otherwise we can not trust the frame work to do its work. This is what my research has learned me. Hope you can follow my explanation. Ther is a research project going on checking the quality of the STL framework using FEA.
  10. Yes David, but it is far more difficult making multiple marching shape and thsu it is difficult to know and produce multiple result. My research is making a number of instruemnets with the same structure as it comes to the geometry and I graduate the thickness different due to the different wood quality. I make three equal instruments, just now, and give them all the same mode 2 and 5 and finally (not yet) I get the acoustic result. Howvever I also must adjust the dynamic condition and that I do by polishing the varnish or scraping the wood surface.
  11. How many did you made yourself. This eem to bee of great importans to you fro some reason. I'm not a professional violin maker but I can say you cannot learn any by looking at a picture. That's the reason why I have choosen not publishing pictures. But take a look on my Facebook. I hope that satisfy your demand. I see nothing extra for you or any other to learn by that.
  12. Do the number of made instruments say anything special for you? If you like to see some of the instruments I made you may visit me on Facebook. Ther are some pictures.
  13. I hope you understand the instruments weight does not inctrease or move in any direction by string load. So what happens? Where are forces go and affect the structure? You seem to have an answer on that sop please explain for us.
  14. Wood Butcher, from what wisom did you make your anounment, Zuger did probably made only one prototype instrument?
  15. First we sart by making a specific arching shape with sevaral qualities. I do not look at all what sound may come out. After that I searched for how does that structure become stress. Which part ie bendin7buckling more than other. How is the volume of that structure affected. Parameters such as specific wood quality are not considered at that time since we have may different wood qualities and it is not possible to make any good understanding that far. The shape of the arching has large impact on hoe long time creep will and can affect the structure. When I found that there is a frame work that hold far higher rigidity the crved arch shapes I understoofd the importans and by theoretical thinking I could see tha there was a function no one ever (as far as I found) has written about. I made a investigation with holografic tools and could show the exsistent function. Thats all research work not claiming anything. The structure I made hold these quality.