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Plate Weight


Shunyata
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13 minutes ago, David Beard said:

Another twist in trying to find meaning in plate weight is that total plate combines edge, channel, and central arched areas.

But the roles of these areas and the significance of their weights in the final instrument are significantly separate.

Exactly

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On 7/2/2021 at 5:42 AM, Shunyata said:

F holes are not cut yet.

Using a phone spectrometer app...

M1 95hz

M2 130hz

M5 275hz

M2 looks quite low, but M5 looks exceptionally low for this stage.  Sometimes there are two resonant peaks in the area, one being lower in frequency than the "real" M5.  You might want to double-check.  I also want to have my F's cut early, to do proper wing fluting and get taptones more representative of the final thing.

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4 hours ago, Anders Buen said:

You sound very bombastic. Almost religious to the book of Patrick Kreit. A lot of things happen when a plate changes MC. One of them is that the shape may change, that influences the tap tones, in addition to the effect from the wood properties. A plate as a humidity meter is not very practical. Another method could be to measure dimensions at a high accuracy, although the shape shift may make that difficult too.

In the narrow space of that it is bull's eye.

I am testing the limits outside that framework...

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On 7/2/2021 at 4:08 PM, Anders Buen said:

Easier with the weight, as the moisture content (MC) comes straight off the weight variation if the dry weight is known. The wood both goes softer and becomes heavier with higher MC so it would probably be possible to monitor the humidity by the tap tones as well. 

 

7 hours ago, Anders Buen said:

You sound very bombastic. Almost religious to the book of Patrick Kreit. A lot of things happen when a plate changes MC. One of them is that the shape may change, that influences the tap tones, in addition to the effect from the wood properties. A plate as a humidity meter is not very practical. Another method could be to measure dimensions at a high accuracy, although the shape shift may make that difficult too.

 

7 hours ago, Anders Buen said:

The MC and RH curve is not linear.

 

3 hours ago, Peter K-G said:

I know, but within a limitid space it is

Anders,

My NO, was not specific pointed to your post.

It's just that I really do data measurements, over a long period of time and the data speakes for it self.

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Isn't it logical that wood density and stiffness are related to each other?

Isn’t also logical that arching shape and stiffness are related to each other?

Isn’t it logical that we must understand the complexity of both together?

Why than is this not discussed?

For me arching shape has big impact especial when the instrument comes under string load.

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16 minutes ago, reguz said:

Why than is this not discussed?

It has been... ad nauseum.

I think this thread is more about practical recommendations for a specific plate... and not an opening to regurgitate pet theories.

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Don, you were right about the frequencies.  I spent more time figuring out how to get use the phone app effectively.

Weight is currently 70g.

M1 116

M2 248

M5 419 (I think... the amplitude is low so I need to play around with the integration settings to get a clearer read.)

2.1mm in upper lung, 2.3 near edge.

2.2 in lower lung, 2.4 near edge

2.3 in center, 2.5 at post, walls 2.9.

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Presumably the F's are still uncut at this point.  It's relatively thin right now, and I don't think there's much to be gained (or lost) by going thinner.  I'd probably stop about here, lose a few grams cutting the F's and final edgework/cleanup.

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To all responders... this entire discussion and encouragement has been very helpful.  (...except for the unkind suggestion that I throw my work in the fire)  Without your enthusiastic support i would not have persevered at getting this plate to such a better place!

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13 hours ago, Shunyata said:

Don, you were right about the frequencies.  I spent more time figuring out how to get use the phone app effectively.

Weight is currently 70g.

M1 116

M2 248

M5 419 (I think... the amplitude is low so I need to play around with the integration settings to get a clearer read.)

2.1mm in upper lung, 2.3 near edge.

2.2 in lower lung, 2.4 near edge

2.3 in center, 2.5 at post, walls 2.9.

95 sounds correct

116 could be right without f's but as thin as it is I doubt it.

but 248 is mode 3

419 is mode 6 if there is minimum amplitude.

 

Now this is starting to look like the stiffest piece of spruce ever recorded.

Better call Guinness.

Are you holding by hand and tapping,, using a speaker or what?

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14 hours ago, reguz said:

Isn't it logical that wood density and stiffness are related to each other?

Isn’t also logical that arching shape and stiffness are related to each other?

Isn’t it logical that we must understand the complexity of both together?

Why than is this not discussed?

For me arching shape has big impact especial when the instrument comes under string load.

Yes all of this is logical, perfectly logical.

Actually it is discussed all the time.

How violins change as they get older and the stresses settle in and equalize and the violins will improve with time.

And the conversation goes as far as to speculate,, how to build them so they will be closer to that goal right up front.

But no one dares to relate it to what you are talking about, somehow there is just no connection made.

It actually makes me laugh out loud, gives me a real chuckle.

Oh well,,,,,,

I have built STL violins for a long time, not all of them. I do lots of drastically different things,, it's just part of the fun and the challenge. Different arching gives different tonal results. There are other ways to equalize the stress throughout the plate.

But every STL violin I have made has been superb, I just finished one and it doesn't disappoint, it's fantastic, I wouldn't change a thing.

I will say that STL's work good on the top, but they are not as necessary for the back, it is a different dynamic going on.

Actually they are not necessary for the top either, lots of great fiddles don't have them,, but they do give results.

When I teach violin making I teach people to use them as they have a better chance of success, because the STL design covers a lot of beginner mistakes and the results are  good.

You also should realize that the STL design is not strictly limited in every detail to the way that you see it. There is some leeway in the application. However the last violin I made, is pretty much consturcted in your view of it,,  but on the top only,, it is very very,, good.

When people aren't interested in what I try to show them,, I keep it to myself.

I don't have that many pearls and there are lots of pigs out there.:D

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Hi Evan Smith. It's kind of you replaying on a subject that is a problem for all makers. How do we shape the arching and what thicknesses should we give the plates. I my selves decided to make a study finding out if there are secrets hidden based on simple geometry on arching shape and I found much more I did not expect to find. I have made all my instruments since then and they all have good sound. The prof. Erik Jansson at KTH Stockholm learned me checking the quality of an instrument by playing the open G-string. Producing and analyzing the sound spectra we actually can see the spectra that tell us about the function of arching shape. I have helped quite many makers and they all make their very best instrument. It's nice to read that also you have good result. What is important with STL condition is that also the inside structure must hold STLs att the same location the outside. It is very possible that the great makers in their workshop let their workers make the the arching shape with the help of templates. Well finished he checked the result of STL and made necessary adjustment and the workers could continue with the inside. In Cremona at a workshop I held one of the makers worked like this but did not know anything about STLs. They came about perfect. He is one of the may good makers in Cremona with gold medal result. I only tell what I have found out and make no claims. Many makers have very good results but no one can tell you why. They simply do not know anything about the quality of their arching expressed by a precise geometric map. So there are many ways of succeeding. I wish you all the best in your making.

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  • 1 month later...

I wanted to thank everyone for your kind guidance as I worked the plates for my latest violin.  You encouraged me to go far lighter than I have in the past.  And now that I have completed that violin, it is definitely the most mature sounding violin I have produced yet.  And its ability to produce soft sounds and harmonics is amazing.

Thank you all again.  I have learned so much from you all.

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8 hours ago, Shunyata said:

I wanted to thank everyone for your kind guidance as I worked the plates for my latest violin.  You encouraged me to go far lighter than I have in the past.  And now that I have completed that violin, it is definitely the most mature sounding violin I have produced yet.  And its ability to produce soft sounds and harmonics is amazing.

Thank you all again.  I have learned so much from you all.

Would there a sound sample be available? 
if you would provide as well technical data like final weight of the top (with and without bass bar) as well as string angle and bridge height bridge weight this would  certainly contribute to the education of every one.

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52 minutes ago, Andreas Preuss said:

Would there a sound sample be available? 
if you would provide as well technical data like final weight of the top (with and without bass bar) as well as string angle and bridge height bridge weight this would  certainly contribute to the education of every one.

How does one usually make a sound sample.  I dont have any recording equipment, just a phone.

Final weight without bass bar 68g

Didn't weigh after bass bar, but I follow Johnson and Courtnall bass bar measurements pretty precisely.

String break angle 158 deg measured on A string.

Bridge height 31.5mm

Didn't weigh bridge. The thickness at the feet was about .1mm less than Johnson and Courtnall measurements, but the rest of the dimensions were spot on.

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