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10 minutes ago, MikeC said:

Hi Andreas thanks for your comments.  I have a couple questions.   When you say the difference to the original Cremona system is that he works from the outside to the inside.   What is the alternative?  What is the 'original Cremona system'?

You say DG did it differently do you have any idea of his method? 

my outline is a little bit distorted that's why I had to scrap my first drawing and start over.  Marking the center line more carefully but still the center points for the F holes are off slightly one side vs the other side.  I may have to cheat a little bit Strad style.  :)  

I got in a dispute about this with David Beard. Who interprets the design of all Cremonese instruments on a geometrical way with limited choices for alterations. 
 

Ok, the simplified explanation is that you can draw a circle through the center of the lobes in what I call the Amati system. The center of this circle equals 5/8 of the body length. (Initially I thought it is the golden section, and here I agree with David Beard that proportions were only built from whole numbers) 

This f hole circle radius is 5/8 of a circle you can draw through the purfling corners. 
 

There seem to be some imprecisions coming from the fact that if you take the whole length in the flat and transfer the proportional length on the arching that it will shift upwards or downwards on a photograph.

On strads starting from around 1700 I couldn’t find this any more. Though in a mathematical sense it seems evident that you can always can precisely connect the center of the lobes with a circle line, in baroque construction with an asymmetric outline this is not always the case. On strads, despite his work precision, this is less precise than del gesu before 1740 (When he still worked nicely)

i don’t know if I have time to dig out my material on this this week. 

 

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35 minutes ago, MikeC said:

When you say the difference to the original Cremona system is that he works from the outside to the inside.   What is the alternative?  What is the 'original Cremona system'?

I think this is one of the few things where Roger Hargrave is wrong. The drawing by Stradivari is in my view not the universal rule for the f hole placement in Cremona. 
 

i see I strads work after 1700 the attempt to streamline all working procedures in every possible aspect of making instruments on an ‘assembly line’. This means for time consuming adjustments to find a better and more practical way. If you try to make a mirror image outline with the baroque construction method it is possible but in a certain way a PITA. 
Therefore it is much easier to look on proportions on one half and reconstruct the placement of the f holes from those measurements on the other side. Therefore you MUST work from the outline to the inside. Therefore the drawing shows only one half. (From the top of my head always the treble side which is the one which doesn’t follow the overall proportions. I find it interesting too that Stradivaris drawing DOES NOT show on the drawing anything in respect to overall proportions. 
 

I think Strad cut f holes with a fly wheel driven saw, he made assembled purflings in really huge bulks, he cut the heads IMO with a jig (though this is debatable) and certainly works simultaneously on 3 maybe 4 instruments. (Though according to bob Bein dG worked simultaneously on 3 instruments as well.) 

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I think that violins made on the same form would be close enough in size and shape that they could use the same F hole positioning.  So Strad could make one drawing and just use dividers or compass settings from that to do both sides.   Maybe use a different drawing for each form.  

In this image I'm sure most of us are familiar with I noticed something in the dots that are hard to see since this isn't a good quality image.  If you enlarge it and look carefully there is a mirror image of the side.   I'm not sure what the significance of that is but it's there.   I darkened the dots to make them more visible. 

 

 

Strad F hole geometry.png

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I'm not satisfied with positioning yet either.   Using the placement geometry I seem to get some asymmetry so I cut out my drawing and folded it half thinking my plate was asymmetrical but it's pretty darned close to perfect symmetry so my drawing must be off some even though I was careful in drawing it.   I think I will have to move the F's around some to make them work well.   I need to print out an F template or trace from the Titian poster.  

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6 hours ago, MikeC said:

I found a much better photo of the drawing posted earlier.   It seems to have some circles with compass points near the right hand edge that look about the same size as the upper eye of the F hole. 

 

Strad F hole drawing 1.jpg

The shadow drawing you see, couldn’t this be a drawing on the other side of the paper?

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10 hours ago, Andreas Preuss said:

The shadow drawing you see, couldn’t this be a drawing on the other side of the paper?

It could be perhaps but I don't know how thick the paper is or how deep the ink penetrates.  So that's a possibility.  

I wonder why many of Strad's drawings and other drawings from that time are made with dots or short dash instead of a solid continuous line.  

 

 

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4 hours ago, MikeC said:

It could be perhaps but I don't know how thick the paper is or how deep the ink penetrates.  So that's a possibility.  

I wonder why many of Strad's drawings and other drawings from that time are made with dots or short dash instead of a solid continuous line.  

 

 

I would construct it like this:

Since the dots and the silver pen line align very well they must have come From a pattern. I assume that Strad wouldn’t make a pattern from scratch but just take an existing rib garland for this. It is clear too that you won’t do it with ink because it would stain the rib garland. 
 

working from the points and the silver pen line  you can connect them with straight  ink lines between the dots but it looks nicer if they are not connected. The silver line alone would be too weak. 
 

Logic?

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10 hours ago, Andreas Preuss said:

I would construct it like this:

Since the dots and the silver pen line align very well they must have come From a pattern. I assume that Strad wouldn’t make a pattern from scratch but just take an existing rib garland for this. It is clear too that you won’t do it with ink because it would stain the rib garland. 
 

working from the points and the silver pen line  you can connect them with straight  ink lines between the dots but it looks nicer if they are not connected. The silver line alone would be too weak. 
 

Logic?

Sounds like a reasonable explanation to me. 

Also I think you are right about the back side of the drawing.  Notes I found say that it is for the B form cello and revers side for the small B form.    Pin pricks for transferring the form to an instrument.   

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