sospiri

Rib Taper hypothesis #43,759

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15 hours ago, uncle duke said:

I use three screws one placed 100mm from the neck edge, 173mm at the middle area and 250mm for the back half.  By the time I'm through carving they are coming loose.  It's just a method I thought would work before I found Maestronet.  I carved exterior arching for 28 -30 plates so far, seems o.k. to me. 

With the D.G. plates - are there any signs of more than one pin location like around the 95 -100mm area and 245 - 270 mm area on the glue line measuring from neck towards the end?  That would be between the upper bout widest and upper corners and well behind the bridge area for the other.

I should mention that I trace around the inner form with ribs glued onto the flat board so that placement is consistent everytime for the plates or in other words the screws are always in the same location no matter the build.   It just seemed a simple thing to do.

I am not aware of Del Gesù or Amati with traces of other pins than the central one.

I would be worried about holding the plate with three screws on the central joint. Probably nothing happens, but concentrating the force there could potentially cause a dangerous leverage effect.

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11 hours ago, sospiri said:

So you think you can give me trumpet lessons?

Maybe, if you've never played trumpet before. But I should warn you that I haven't played trumpet since my late teens. :D

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1 hour ago, Davide Sora said:

Not that I'm aware of.

It makes me wonder why did Amati and DelG have the pin hole but not Strad.  Also I seem to remember reading somewhere that Stainer had multiple holes,  five or six maybe.  This makes me think it may have been a way to measure the thickness along the length of the instrument.   But there are historical instruments that have a sound post with a metal pin fitted at that location into a hole in the back so maybe Amati and DelG used a centrally located sound post with the ventral pin hole as it's location.  Strad always the modern innovator moved it to the bridge foot and eliminated the metal pin and hole.  

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1 hour ago, Davide Sora said:

I am not aware of Del Gesù or Amati with traces of other pins than the central one.

I would be worried about holding the plate with three screws on the central joint. Probably nothing happens, but concentrating the force there could potentially cause a dangerous leverage effect.

I would worry about that also.  If I were going to screw the plate to a board I would put the screws offset from the center line and would not have them penetrate the plate very far.  

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1 hour ago, David Burgess said:

Maybe, if you've never played trumpet before. But I should warn you that I haven't played trumpet since my late teens. :D

I taught myself to play many years ago. I was just joshin with you and Michael, because I learned enough music theory to know it's better just to play than to theorize.

Same thing with outlines and arching, I don't wanna overthink it, just do it. I don't care if it's wrong, what better way to learn? 

 

 

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42 minutes ago, MikeC said:

It makes me wonder why did Amati and DelG have the pin hole but not Strad.  Also I seem to remember reading somewhere that Stainer had multiple holes,  five or six maybe.  This makes me think it may have been a way to measure the thickness along the length of the instrument.   But there are historical instruments that have a sound post with a metal pin fitted at that location into a hole in the back so maybe Amati and DelG used a centrally located sound post with the ventral pin hole as it's location.  Strad always the modern innovator moved it to the bridge foot and eliminated the metal pin and hole.  

So there were metal pins in some instruments?

 

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28 minutes ago, MikeC said:

It makes me wonder why did Amati and DelG have the pin hole but not Strad.  Also I seem to remember reading somewhere that Stainer had multiple holes,  five or six maybe.  This makes me think it may have been a way to measure the thickness along the length of the instrument.   But there are historical instruments that have a sound post with a metal pin fitted at that location into a hole in the back so maybe Amati and DelG used a centrally located sound post with the ventral pin hole as it's location.  Strad always the modern innovator moved it to the bridge foot and eliminated the metal pin and hole.  

Good question, but not knowing what the pin's function was, it's hard to guess why Stradivari didn't use it. Maybe he used a different system or he just did a cleaner job and was careful not to drill too deep a hole if that was the case. I drill a hole as a reference for the center of the back thickness, but I never leave a trace in the finished work.

I don't know anything about Steiner's holes, but they could be traces of the thicknessing punch if they are found in random positions, as is sometimes also found in Stradivari.

I don't know anything about the metal pin you are talking about, sorry, or who was the first to put the soundpost in the current position near the foot of the bridge, but tendentially I would think that it was not Stradivarius but someone well before him

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20 hours ago, uncle duke said:

Always leery of going through I am careful.  My dimensions for the board is 29" long x 13.5 " wide though for easier working I need to lose three inches in the width to 10" wide.  1/2" thick mdf is all it is.  

The 29" width works well for clamp room and forearm resting while carving, gouging and chiseling.

Just to cover my owns self in case someone chooses to try this in the future - I used 11/16 thick mdf instead of 1/2.  Counter sink the screws from underneath.

Now, if I just lengthen this flat board to 90" x 20" I could work on multiple plates at one time without having to move around very much.  Hmm, that should chaff the competition around my neck of the woods some.

Ain't happening - I don't have the room.

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2 hours ago, MikeC said:

Referring to this article it appears that in some early instruments there was a centrally located soundpost with a small metal pin fitted into a hole in the back plate.  

http://www.christianrault.com/en/releases/how-when-and-where-the-specific-technological-features-of-the-violin-family-appeared

 

central soundpost.PNG

Thanks for posting, the theory is interesting and could even be plausible, but I am more of the opinion that the pin was a reference tied to thicknessing of the back. A doubt that could be raised is why the soundpost positioning hole was only on the back and not also on the top, and why it goes so deep through the thickness, with an evident risk of cracks that even a medieval craftsman would have been well aware of. Putting a column of reinforcement that has to withstand pressure and also ending in a pointed cone running through the thickness would have been complete nonsense, in my opinion, and we would certainly have evidence of cracks at the pin in many violins if this had been the case.

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17 hours ago, Davide Sora said:

Thanks for posting, the theory is interesting

Theories are not always opposable.

I mean that we must  consider that a theory can complet an other one.

but actually, in this exemple it is not a theory it is a fact : on this untouched instrument of Frieberg the sound post is set on the axe

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23 minutes ago, francoisdenis said:

Theories are not always opposable.

I mean that we must  consider that a theory can complet an other one.

but actually, in this exemple it is not a theory it is a fact : on this untouched instrument of Frieberg the sound post is set on the axe

Yes, this is a fact, the theory is that the central pin has to do with this fact, which is certainly not demonstrable and therefore remains a theory.

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52 minutes ago, Davide Sora said:

Yes, this is a fact, the theory is that the central pin has to do with this fact, which is certainly not demonstrable and therefore remains a theory.

It is demonstrable as a hypothesis if it is demonsrable as a fact that it is an original feature.

But the Luthier who put it there may have believed his own hypothesis that the central pin and sound post as an original Amati feature was factual and not hypothetical.

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I don't think it mentions a date for the instruent in the cathedral but it say 'almost contemporary with Andrea Amati'.  Interesing also that rather than a base bar it seems to have two bars in an X pattern sort of like a guitar.  From the front view the post appears to be slightly off center towards the base side.  

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20 hours ago, MikeC said:

I don't think it mentions a date 

untouched since 1594

 

20 hours ago, MikeC said:

Interesing also that rather than a base bar it seems to have two bars in an X pattern

Theses "bars" doesn't exist on the original Xray shot

 

23 hours ago, Davide Sora said:

Yes, this is a fact, the theory is that the central pin has to do with this fact, which is certainly not demonstrable and therefore remains a theory.

Yes , it's true that the fact doesn't apply to cremonese instruments.  

about the central pin I record 3 ideas ("theory" is may be an ambitious word for such a detail)

-a central sound post

-a remind of thickness process (need to be describe)

-a remind of a clamping system

any other ideas?


PS: we have some allemanique instruments with 2 or 3 pins in the back

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2 hours ago, francoisdenis said:

untouched since 1594

Theses "bars" doesn't exist on the original Xray shot


PS: we have some allemanique instruments with 2 or 3 pins in the back

Thank you,   yes when I enlarge the image I see the cross lines are a false artifact from the xray.  One line goes across the treble F hole.  

 

This is where I read about Stainer having multiple pin holes.   Sorry this has strayed away from the original rib height discussion.   

 

 

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On 11/20/2020 at 9:57 AM, francoisdenis said:

about the central pin I record 3 ideas ("theory" is may be an ambitious word for such a detail)

-a central sound post

-a remind of thickness process (need to be describe)

-a remind of a clamping system

Making a hole in the point where you want to leave the maximum thickness is useful to be able to position it accurately when the board is flat (before starting to dig the inside, for example at the intersection of the two diagonal lines that connect the tips of the ribs) and not having to continuously reposition it by making other measurements during working, that would erase it at each gouge stroke. Even using it as a center for a compass to trace any curves to be used for measuring the thickness in specific areas would significantly deepen it, leaving it visible even when in the finished work.

I know, it is a somewhat weak and difficult to prove justification, but in light of my work practice it makes some sense to me, and I don't have a better one.

What I cannot understand following my hypothesis, is how it was possible to leave a hole so deep, which sometimes almost completely crosses the thickness, sometimes so much to be visible on the outside. Perhaps it could be an error in assessing the initial depth of the drilling, or the proverbial inaccuracy of the Del Gesù.:P

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36 minutes ago, Laurentius said:

Roger Hargrave goes into great detail on this little pin in his excellent article concerning the Cremonese methods of construction.

The thinking is this pin was put in to fill a hole made for one leg of a large compass or dividers to fit into, the other leg scribing the thicknessing pattern for the back.   He notes that as the Cremonese method of thicknessing went from the thickest part of the back being in the center  to moving it up so the thickest part was above the center, such as you see in the Sacconi book,  the location of the pin in Guarneri family instruments moved upwards also, further evidence that it had something to do with thicknessing.  He also notes he has seen a viola made by Deconet with a hole (or pin) in the thickest part of the back, the scribe lines from the compass are still visible, and Deconet was most likely a student of the Guarneri's, and so would have learned the method from them.   

Why would there be no pin in the top?  I am conjecturing that since the rough thicknessing was simple, basically starting out with a one thickness measurement,  no hole and compass was thought necessary.  

There is a picture of a paper or cardboard marking template that would do the same thing in the Hill book on Stradivarius.  We all made one in school. It seem Strad had figured out a way to mark the pattern for thicknessing the back without a hole or a compass.

This is what I was saying too, but why leave such a deep hole? I use the compass system that Hargrave describes, but it has never happened to me to leave a visible hole, and I don't think the Amatis were so careless in their work. Thus the question remains open.

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3 hours ago, Laurentius said:

Why would there be no pin in the top?  I am conjecturing that since the rough thicknessing was simple, basically starting out with a one thickness measurement,  no hole and compass was thought necessary. 

I think the Amati family thicknessed the tops the same as the backs 

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3 hours ago, Davide Sora said:

This is what I was saying too, but why leave such a deep hole? I use the compass system that Hargrave describes, but it has never happened to me to leave a visible hole, and I don't think the Amatis were so careless in their work. Thus the question remains open.

Well, the conical hole almost always goes through the back plate as it does on the 'Cannon' that is more than 6 mm of maple. The Giuseppe 'filius Andreae' Guarneri in the MdV of 1689 has the dorsal pin filled with wood but it too passes through to the outside and that is over 5 mm thick.

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1 minute ago, Bruce Carlson said:

Well, the conical hole almost always goes through the back plate as it does on the 'Cannon' that is more than 6 mm of maple. The Giuseppe 'filius Andreae' Guarneri in the MdV of 1689 has the dorsal pin filled with wood but it too passes through to the outside and that is over 5 mm thick.

Apart from the Amati, Guarneri, and Deconet, who else used these? I have heard that they show up in post-1730ish Carlo Bergonzis (some say they were added, some say original) and possibly Camillo Camilli - are there any others?

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Just now, Three13 said:

Apart from the Amati, Guarneri, and Deconet, who else used these? I have heard that they show up in post-1730ish Carlo Bergonzis (some say they were added, some say original) and possibly Camillo Camilli - are there any others?

Amati family except late Hieronymus II. All the Guarneri family. Camillo Camilli [from Peter Guarneri of Mantova) (but for Camilli not so deep. Some of the early Bolognese makers (Tononi, Guidantus, Don Niccolò Amati [not always]-) and other I can't think of at this time of day. Bergonzi is likely a later addition.

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On 11/21/2020 at 9:14 AM, Davide Sora said:

This is what I was saying too, but why leave such a deep hole? I use the compass system that Hargrave describes, but it has never happened to me to leave a visible hole, and I don't think the Amatis were so careless in their work. Thus the question remains open.

   ;)

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