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the function of arching shape


reguz

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 the arching is what makes your stringed instrument sound and function the way that it does. Without those curves (that is, with a flat top and back) your instrument wouldn't be able to stand up to the pressure of the strings.

What would you say by reading these lines?

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The main function of the arching is the stability it provides the instrument for its rather thin plates. Moreover, the arching makes it possible for the bowed instruments to go through humidity cycles through the year and with travelling A to B in climate C, like a dry airplane cabin.

The tonal aspects of the arcing is a secondary effect. But it is probably there.

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33 minutes ago, Andreas Preuss said:

False. Then you could use paper ribs.

False. Then you could use ANY string angle.

I found that if the string angle is too shallow over the bridge (approaching 180 degrees) that there isn't enough downward string force.  The strings can be pushed out of their bridge notches with heavy bowing.

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3 hours ago, reguz said:

 the arching is what makes your stringed instrument sound and function the way that it does. Without those curves (that is, with a flat top and back) your instrument wouldn't be able to stand up to the pressure of the strings.

What would you say by reading these lines?

I would say that I'm suddenly feeling very sleepy ...

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I would agree that good arching is important to the sound and that flat plates on their own would not hold up well to string pressure.  Guitars have bracing under the sound board to provide support.  Also on a guitar the strings are usually pulling up on the sound board not pressing down on it, with some exceptions. 

Obviously the strings have to be on an arched bridge to be able to bow one at a time, that wouldn't be possible on a flat bridge like a guitar. 

 

Guitar.jpg

 

If you want to see an example of bad, or at least unconventional arching check out this VSO build on youtube. 

I don't know if he is purposely making it rustic for the old sailing vessel Tally Ho or just clueless about the architecture of a real fiddle.  

 

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1 hour ago, Don Noon said:

I would say it's bait for letting you expound upon your theories... again.

Don. The sentense you were able to read are not written by me. It is copied from the internet. But as always from you, you have  nothing to contribute.

No Don, it is just for you to let us know your opinion. You seem to be unable

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1 hour ago, Anders Buen said:

The main function of the arching is the stability it provides the instrument for its rather thin plates. Moreover, the arching makes it possible for the bowed instruments to go through humidity cycles through the year and with travelling A to B in climate C, like a dry airplane cabin.

The tonal aspects of the arcing is a secondary effect. But it is probably there.

Yes, yopu could of course look at the problem from that aspect but the question remain why is it from a technical aspect? How does the arching shape start behave? What is it we like it to behave?

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1 hour ago, Marty Kasprzyk said:

I found that if the string angle is too shallow over the bridge (approaching 180 degrees) that there isn't enough downward string force.  The strings can be pushed out of their bridge notches with heavy bowing.

This is an answer related to the behavior of the string and the bowing action. It is not about arching shape. I belive you can do better.

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53 minutes ago, MikeC said:

I would agree that good arching is important to the sound and that flat plates on their own would not hold up well to string pressure.  Guitars have bracing under the sound board to provide support.  Also on a guitar the strings are usually pulling up on the sound board not pressing down on it, with some exceptions. 

Obviously the strings have to be on an arched bridge to be able to bow one at a time, that wouldn't be possible on a flat bridge like a guitar. 

 

Guitar.jpg

 

If you want to see an example of bad, or at least unconventional arching check out this VSO build on youtube. 

I don't know if he is purposely making it rustic for the old sailing vessel Tally Ho or just clueless about the architecture of a real fiddle.  

Sorry but I did not find any about arching shape.

 

 

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1 hour ago, Anders Buen said:

The main function of the arching is the stability it provides the instrument for its rather thin plates. Moreover, the arching makes it possible for the bowed instruments to go through humidity cycles through the year and with travelling A to B in climate C, like a dry airplane cabin.

The tonal aspects of the arcing is a secondary effect. But it is probably there.

I started making my top plates like the wood floors of buildings which have thin flat plywood backed by many deep floor joists.  If you drop a barbell on the floor it can produce a loud sound and its various mode frequencies can be adjusted by using different spacings, widths and heights of the floor joists and their cross bracings.

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2 hours ago, Don Noon said:

would say it's bait for letting you expound upon your theories... again.

Yup. Most of us have learned to no longer take that bait, after having already heard his theories too many times.

2 hours ago, martin swan said:

I would say that I'm suddenly feeling very sleepy ...

Me too...

56 minutes ago, reguz said:

No Don, it is just for you to let us know your opinion. You seem to be unable

Being unwilling is not the the same thing as being unable. :P

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1 hour ago, Marty Kasprzyk said:

I started making my top plates like the wood floors of buildings which have thin flat plywood backed by many deep floor joists.  If you drop a barbell on the floor it can produce a loud sound and its various mode frequencies can be adjusted by using different spacings, widths and heights of the floor joists and their cross bracings.

Yes, relevant observations there for e.g. concert hall floors, sound insulation properties of walls or ceilings made of plates on stiff studs or absorbing wall or ceiling linings of a similar construction. 

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1 hour ago, reguz said:

Yes, yopu could of course look at the problem from that aspect but the question remain why is it from a technical aspect? How does the arching shape start behave? What is it we like it to behave?

The arch is likely to come from empirical means. Some stringed musical instruments are made of natural cavities from seed containers, or the like. Some are simply hollowed out. 
By the answers here I can see that you are likely to have the "answers to all this" yourself, and do not pay attention to what I have written.

Moderately curved plates work better because they can be made thinner and the design, if it is of the right type, will resist and survive humidity cycling better than the less good designs, like too high arch and too fast changes of the curves.

Arch suppress the low frequency response and does little to the highs. Maybe a balance there is achieved in better instruments. It is perfectly possible to make a useless instrument with "right arch", but other important factors incorrect. Arching itself does not make the sound. Violin sound and instrument stability is a balancing act of lots of factors.

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I would say that an ideal arching shape is the result of a purely functional, planned geometric approach. The basis of that is its height determined by the shape of the long arch, and inflection point positions between the upper and lower bouts. Fixing those is the only practical way to preplan an arching. And, if you can't preplan it, how can you lay down any innovation which supposedly will improve the instrument's performance?

The Tally Ho video shows the formula or approach to the arching of that violin is totally uncharacteristic of traditional violin making. There is no smooth connection between the upper and lower bouts through the centre bout. There are ridges at each of the corners. Recurves around the upper and lower bouts are almost non existent. I would say it's a good example of how not to go about arching. It doesn't look right and probably isn't.

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