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Joaquín Fonollosa

Geometría fabrorum

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Has anybody had a chance to see the new book:

"Antonio Stradivari.Le chitarre- The guitars" by Gianpaolo Gregori, English translation by Cecilia Gregori

il mio libro self publishing, 2019

ISBN 978892358171

It has on its cover the outlines of five Stradivari guitars. The book might give us some insight into how these shapes were generated.

A. Strad. Le chitarre.jpg

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On 10/18/2019 at 6:04 PM, Marty Kasprzyk said:

Has anybody had a chance to see the new book:

"Antonio Stradivari.Le chitarre- The guitars" by Gianpaolo Gregori, English translation by Cecilia Gregori

il mio libro self publishing, 2019

ISBN 978892358171

It has on its cover the outlines of five Stradivari guitars. The book might give us some insight into how these shapes were generated.

A. Strad. Le chitarre.jpg

Interesting, I didn't know this book yet....

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Cool thread. I'm trying to work through the Denis method from his "Two Violins" paper, which is free online. I'm having trouble following the geometry. I'm fine until this step of finding q and qq. There is no way the upper bouts are 8 units. Something seems to be missing. Can someone who has done this help me out?  My husband is installing an organ several states away and he won't help me, he's not in violin mode or something. 

 

https://www.scribd.com/document/189540850/TwoForms-Denis

 

I would take photos of what I have done...but...uh...the uploader isn't working.  Haha, it's true though. I tried.  I'm stuck on part 3 of step 6.

 

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12 hours ago, not telling said:

There is no way the upper bouts are 8 units.

Yes, you divide it in 8 units . Speaking of "relative measurements "unit"  is a kind of equivalent of  "the part of a ratio" 

You have a "unit" each time you use a ratio which can be  the same...or not

(Actually in this case you set all the measurement of the width using twice the section 3-5)

and you do that using the Thales theorem  :)

1160177652_Capturedecran2019-10-21a16_14_24.thumb.png.4a9af4b6248be515ba24b71290fec329.png

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6 hours ago, francoisdenis said:

Yes, you divide it in 8 units . Speaking of "relative measurements "unit"  is a kind of equivalent of  "the part of a ratio" 

You have a "unit" each time you use a ratio which can be  the same...or not

(Actually in this case you set all the measurement of the width using twice the section 3-5)

and you do that using the Thales theorem  :)

1160177652_Capturedecran2019-10-21a16_14_24.thumb.png.4a9af4b6248be515ba24b71290fec329.png

Oh! There's the 8. That's doable, but I wouldn't have come up with that from the article alone.  Obviously I need your book. Thanks.

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Regarding the guitar anaylsis proposed by Francois Denis...
 

Please have a look at an alternative analysis. I've attached it as a word file as the entirety of text,  tables and pictures didn't copy and paste very well. 

Thank you to all who've shared their knowledge and ideas in this fascinating thread. I'd be interested in getting feedback from people who know more history, maths and computer graphics than I do.
 

many thanks
Elinore

Analysis_of_Strad_Rawlins_Guitar.docx

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Again, it's dangerously misleading to work only with a few extracted point to point measure.

30 point to point measures, or even hundreds of such measures are greatly insufficient compared to the literally infinite number of such measures contained in a full shape.

This is working too much in the dark.

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