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Stradivari tools, again


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55 minutes ago, Kimmo89 said:

But the hole in the middle and carved slot for bolt head would tell there is much missing from this cradle.

I suspect it has been rotatable, and the notch could be only for smaller clamps to hold plates not to move upwards.

Would be great to see the other side of the cradle, then it would tell all, if there is rotating scratches.

I agree completely.  I am not aware of such a photo.  

I did not cut the rectangular hole for the bench screw that is seen in the original.  The basal notch on the original is above, not below the bench screw hole.  In the museum photo, the corner block template points directly at the notch of the cradle.  The wood around the notch is heavily worn.

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1 minute ago, francoisdenis said:

Could you explain a bit more your idea?


I lost interest in modeling after the forum reacted to my explanation.

Try linking the width of a forma at its narrowest point to a circle with a radius the same as the forma C-bout diameter. Early forms like Amati and early Strad are best to start with.  Guarneri del Gesù is tricky.

Then we need Vitruvius...

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18 minutes ago, francoisdenis said:

I agree that it's a efficient (and rather obvious) way to proceed.

...and what about Viturvius?

It begins, of course, with his man, squaring the circle (no, not the da Vinci cheat).  He uses a similar idea for scaling the based of columns.  One progression shows a hex enclosed by a circle, enclosed by a... Which I called Addie's web, when extended several iterations, and based on a radius equal to the c-bout diameter.  Interestingly, you can construct this the traditional way, or on the computer  by scaling each iteration by the sine of 60 degrees or its inverse.



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The points of measurement of the forma, in order of scale are:

C bout

narrowest point, upper bout

" ", lower bout

widest point, Upper bout

" ", lower bout.

Each of these will correspond to one of the arching circles on Addie's Web, constructed using the c-bout forma measure as a starting point.  Del Gesù's lower bouts are out of sequence.

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16 minutes ago, Addie said:

sine of 60 degrees 

I guess you  are speaking of an hexagone there

5 minutes ago, Addie said:

Each of these will correspond to one of the arching circles

Each of these what? Where do you take exactly the measurements of the various radius. It's not clear for me

Could you provide us a drawing, you are good for that, no?

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2 hours ago, francoisdenis said:

Could you explain a bit more your idea?

There is a simple geometric way of producing the cross arches once the long arch is established.   I may post the method in my build thread but want to test it on more than one violin first to see if it works as a general rule. 

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I'm at my computer now.  Here are my data, and randomly selected images.  I wish to retain copyright where applicable .


The system works for everything except the Guarneri del Gesù "Cessole," which has radii out of sequence.
My numbers are in the following order: curves: Center bout, above upper corners, below lower corners, widest part of upper bout, widest part of lower bout. 1=center bout width of mold, where W=r. Curves are multiplied by 0.866 or its inverse. Negative numbers represent high arch.

For Maggini, I get:
Top: 1, 5, 6, 9, 12.
Back: 1, 3, 5, 8, 10

Stradivari Messiah:
Top: 1, 4, 6, 9, 11.
Back: 1, 3, 7, 10, 11.

Stradivari Viotti 1709.
Top: 1, 3, 5, 7, 11.
Back: 1, 3, 4, 7, 11.

Stradivari Titian 1715.
Top: -1, 1, 4, 6, 9.
Back: -1, 3, 6, 8, 12.

Peter Guarneri of Mantua, 1704
Top: -2, 2, 4, 7, 10.
Back: -2, 3, 5, 9, 12.

Guarneri Filius Andrea
Top: -3, 1, 6, 9 *.
Back -3, 1, 2, 6, 10

N. Amati:
Top: -3, *, 2, *, 8.
Back: -3, 1, 4, 5, 11

Guarneri del Gesù Cessole
Front: 1, 8, 4, 4, 11.
Back: 1, 5, 5, 8, 9.

Bergonzi 1736:
Top: -1, 4, 5, 9, 11.
Back: -1, 3, 5, 7, 11.


Ole Bull back.jpg

Archimidean Arching.jpg

Serlio 1.jpg

Stradivari Flower Rectangle.jpg

Thomae Finkii-1.jpg

Geometria Speculatiua-4.jpg

Real Addie's Web.jpg

Kruze on Addie's Web-2.jpg

Back Arching.jpg

Stradivari arching.jpg

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3 hours ago, MikeC said:

where is the notch located in the original ?   I can't see it in the photo.

It goes just over the middle hole in bottom of the arch.


I also see light seen through the upper hole, might be hole drilled in from the top end, and also, looks like there is possibly hole in the lower end too. Hard to say when all pictures are full of shadows.

If you imagine gluing the crack back together, the hole at top end would look pretty much round. Maybe the crack happened when tightening clamps there 2000 times.


Edit: And I mean holes bored from ends towards the middle hole. In the same direction as the crack.





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OK , I understand that you have a serie of  commensurable radii  based on the minimum width  of the middle bout.

It's averated that the use of commensurable measurement for radiis were  very commun.

Your connexion with the Vituvian figure remains a bit fuzzy for me.
The hexagone is connected with the rotation of the equilateral triangle
The Vituvian figure is "on the other side", in relation with the rotation of the square.
To connect the two  we have to do reference to the hiden symbolic contents of the vitruvian figure. May be another topic....

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