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Posts posted by francoisdenis

  1.  I can't speak about what's going on with the frequency of AO....

    but I noticed that rounded edges appear spontaneously as soon as you used knifes and gouges to cut the "f hole"...


             1424200576_Capture_decran_2020-01-04_a_09_35_30.thumb.png.0876296e8ea8702e1630f540fc36be1a.png     1080832806_Capture_decran_2020-01-04_a_09_36_23.thumb.png.31701ec0a14ae1b9d360128116102b60.png    1869184244_Capture_decran_2020-01-04_a_09_36_34.thumb.png.d2e81aba96cc9da8b5a72cdefc2c4cf6.png  1990633554_Capture_decran_2020-01-04_a_09_36_46.thumb.png.31a0dce6946234225c8af3afc0dc1f8c.png     895727266_Capture_decran_2020-01-04_a_09_35_43.thumb.png.87377d66d421794cba4baf9e1ba66bd9.png   43338892_Capture_decran_2020-01-04_a_09_35_14.thumb.png.de2567ca7a2c769a43c911500aebfe95.png582126215_Capture_decran_2020-01-04_a_09_36_05.thumb.png.bc64e214cb01f905f337372d6502eed9.png    1544829111_Capturedecran2020-01-04a09_37_05.thumb.png.a51ec9e53c25e8802c3e89e035f802fb.png 

  2. 4 hours ago, Christopher Jacoby said:

    Hi Francois! This was me with strings in my late teens and early twenties. Washing my hands well and eating more vegetables and fruit, and less beer and red meat seems the way. An incredible amount of acid used to come off my hands

    So many advises! Somebody ask me a picture . My client just breaks a string yesterday .6D2166F9-696F-4112-BA78-BC363B5BDE57.thumb.jpeg.9d79a6a00f8d516f5fe746edc5e4e77b.jpeg


    I was away from my laptop since a couple of days and I thanks you all for your advices. I think that the answer could be connected to the pressure and time of playing and acidity. The player damaged the fingerboard very quickly (attached picture) and I had to plan it after only few month of playing. I have some femal players which don't reaches a such result after 20 years....So; wash the hands with high PH soap and less pressure on the fingerboard are my first advise. 

    I will say later how it works ....

    PS:  I have to say that neither brand of the strings, their lenght and instrument are in cause 


  4. 11 hours ago, jezzupe said:

    The first thing I would do is check the nut,pegs,tailpeice holes/slots and bridge for sharp edges that could break the string, if thats not an issue, I would suggest his teacher observe his playing in order to make corrections in his playing. I find it very hard to believe that someone is breaking strings from playing too hard, as it's something I've tried to do and never really been able to make happen , even when playing with ridiculous pressure and speed, excluding the e maybe.

    The strings break between the nut and the bridge so the pb is not related to theses points. Right now, I have the pb with a viola player which can break C wolfram in two (often under the annular finger) only the D string (often in aluminum) seems to escape. It's a reason why I 'm thinking to a kind of chimical reaction with the sweat and seeking a way to thwart the effect. I thought that an ointment could help but it should to not make the playing more difficult. 
    It's not a commun pb but a real handicap for the player.

  5. Typically , a young man (between 17 and 20) playing several hours a day  who breaks the strings after a few days only.

    I have encountered this case several times in my career with the only response "it will pass with age".

    Does anyone have a more immediate proposal to solve this problem?

  6. 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  :)


  7. 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....

  8. 10 hours ago, Marty Kasprzyk said:

    "French curves are actually Euler spirals which produce a straight line as the limit approaches zero and the circle as a limit approaches infinity.  

    That matchs our empirical experience , perfect circles and perfect straight lines are an abstraction (all of us have had this experience trying to glue our first cello joint...) . So you have this gap between the reality and the ideal - which is an old philosophical issue.

    circle and straight line are an ideal conception of a reality which, at the end, is more the euler spiral. 

    you will find the same kind of issue with the way the Ancient dealed with integers and irrationals - 
    The beauty is a reality close to the ideal.  It is this way that Ancient Ideals were made - the perfection was only the gods domains

    David you are on the god side and Marty, on the weak humain side :)

  9. 1 hour ago, David Burgess said:

    still think the best path for a maker is to "get an eye" for things, along with "getting an ear" for various sorts of sounds. Yes, it's not easy, and can't be learned in a day from reading a a paper, or a 27-page thread. Based on my interactions with many makers, I do happen to think that this delivers better and more reliable outcomes than over-analysis. At least so far. ;)

    One may also consider (perhaps in a more constructive and realistic way) that it is not one or the other but the one and the other

  10. 13 hours ago, Delabo said:

    OK, so its more about knowing a method like yours ?

    Yes for example, but I am not the only one, the proposals of David and Kevin require only simple measures too (and some others before us, as well). As far as I am concerned, I consider myself more as a historian of the concept of measurement. I read and sometimes studied closely all that I could on the subject. 
    The violin is for me only one example among hundreds of others, the organ buffets interested me, viola da gamba etc ... and since the beginning of this discussion I studied 4 guitars and I am gathering documentation to study 4 others.

    I reacted to your post because you were saying a common untruth - If someone uses (presumably without knowing it) complex maths it's us,  much more than a fifteenth century craftsmen whose methods of measurement are not not so mysterious as that.

    Above all, I try to defend in this thread the importance of the research method to appreciate the quality of a result.

  11. 1 hour ago, Delabo said:

    Quite the opposite.

    I was asking if he was of of at least above average IQ or even more.



    I do not know the IQ of A Amati (and I admit that this subject is of no interest to me) but if you admit that he knew how to count until 12 it is more than enough to make a violin.

    We are very far from complex mathematics ....


  12. 8 minutes ago, Delabo said:

    "Incredibly complex"  - relative -   to what seems a simple task.

    It is "relatively" easy to see how a seemingly simple shape can be drawn by someone on a piece of paper.

    Various curves could be drawn using dividers - rulers - triangles etc and cut out with  scissors and used to make a violin pattern on wood.

    A person with above average intelligence who excells in maths might wish to make this simple task "incredibly complex" because they like doing maths.

    Are you suggesting Amati, Stardivarius, Guarneri were of this ilk ?



    Dear Delabo,

    You're just arguing that Amati was not able to count to 12. Because you do not need to know much more than "complex math" to design a violin 

    you did not read me well where I expressed myself badly

  13. 18 minutes ago, Joaquín Fonollosa said:

    People who seem to have nothing in common .......
    ... "The luthier Max Möckel, who worked at the end of the 19th century in St. Petersburg and Berlin, did not rest until he had investigated the true origin of the architectural and sonic beauty of the violin. His idea was to investigate whether, in the light of knowledge of the Renaissance, it might be possible to discover what role Leonardo da Vinci, Luca Pacioli and Alberto Durero had played in the instrument construction revolution, so he began to look for clues to support his hypotheses in the works of these great artists, and he came to The following conclusion:

        Is there really an Italian secret? Yes and no. If we think of this as some kind of recipe, hidden somewhere in an old trunk, then no. . . We must move to the time when the violin was invented, and to the ideas with which the old masters created their works. . . The most important minds, to name two of them, Leonardo da Vinci and his friend Luca Pacioli, had been interested shortly before, in their work of so many facets, in mathematical problems, and when they saw the triangle and the pentagon, they did not see them merely as simple geometric figures, but they saw in the pentagon, for example, the secret eye of God, a living sensitive image, with its infinite number of relationships, for all that is appropriate.

    With this hypothesis as a starting point, Möckel developed a procedure to build the violin, the viola and the cello, whose model was what Luca Pacioli called the divine proportion (in the divine proportion, the division of a line or a geometric figure is such that the smallest dimension is the largest, as the largest is the whole). Since then, he built many excellent instruments with this method. "

    Are you kidding ?

    Have you read Max Möckel ?  You have to gave up with all these the XIX° century cliché 

    time to move forward

  14. Some new of the Strad Guitar...

    The actual measurements of the Strad Rawlins guitar has been given by Pollens and, good news, the variations with respect to the dimensions of the photo are remarkably low (1.5 mm in length and 3/10 ° in width which is excellent) - We can therefore consider that the analysis that I previously posted here is well founded :)

    Moreover Pollens always seems angry with the relative measurements since the three ratios W / L (body max width / length)  are bad ....
    "Guistiniani" W / L = 2.24 "Hill" W / L = 2.2 and "Rawlins" W / L = 2.08

    the correct ratios are :

    "Guistiniani" W / L = 1.758 "Hill" W / L = 1, 74 and "Rawlins" W / L = 1,644

    Given these surprising errors in calculations Pollens's conclusions are faulty - it does not have a 5/11 ratio and the 5/9 ratio is only found on one paper template ...

  15. 23 hours ago, Delabo said:

    incredibly complex ways

    "incredibly complex ways" ....Sorry but these means nothing-  

    English is "incredibly complex" for me is it for you too?

    complexity is a relative concept as soon as it is connected to ignorance

    Seven different measurement of the foot were used at the same time by the stone carvers to built the Cathedral of Chartres

    would you says that it is an "incredibly complex way" ?

     if you answer "Yes" your thought is addressed to our nowadays commun sens - for us, it is obviously a "complex way"

    if you answer "No" your thought will be addressed to our capacity of understanding this is where the place of complexity is.

    Explaining of our ignorance can be a hard work-  

    I understand and respect the motivations of people who prefer the reassuring idea that there is nothing to understand but here, I see nothing more than a confortable opinion founded on ignorance.

    It is a very normal behaviour ,ignorance, peace of mind and certainties are good friends of all of us. 

  16. I continue to explore the side of guitars-
    I am now studying three Voboam guitars in Paris
    I have good photos and also ... measurements
    Here is an example of a match between a good definition photo and real measurements. (the camera was in a wrong axe)
    I repeat, be careful with photos


  17. 16 hours ago, HoGo said:

    For this simple experiment  better internet photos are sometimes enough, but we ned real size to make sure the width/length ratio is correct to start with (othewise we would get ellipse geometry instead of circle).

    You are right - following my experience, the quality of an analysis depends on the quality of the info

    This kind of bad pictures  (as the Strad guitar) ought to be considered cautiously wether we don"t have the original measurements 





  18. 4 hours ago, jezzupe said:

    I was wondering where that went...I had gone back to reread it and "poof, gone" 

    Is it because there was a link to  a Wiki article?

    Unfortunately only in french - I took time to resume and translate some parts...:(

    history, comparaison between ellyps and "anse de panier"  advantage and disadvantage (can we use "basket handle" in english ?)

    with some remarks about the practice  " The discontinuity of the shape can be hampered by unsightly angles that stoneworkers are not always able to correct"

    about the drawing process, I am struck that geometry remains analytic. Constructions derive from the solution of equations


    they seem to ignore the elegant solution based on the intersection of the same circle....


    like some of us here....




  19. 34 minutes ago, Marty Kasprzyk said:

    I'm sorry for not helping more.  But if you play around a little you will quickly learn all you need to know.  As with any drawing method you first have to chose your length of the instrument and bout widths. 

    This is one of the advantages of using bent ribs--you don't need a lot of detailed instructions.  People in Spain, Italy, Germany, France... don't need translations.  The wood doesn't know where it is or what century it is.

    Ok I will try and will come back to you- but your advise is carbone fiber or wood?


  20. 4 hours ago, HoGo said:

    the probability of drawing new violin shape freehand or using just bent sticks for curves (without tracing existing shape) will contain such ratios and circles with probability smaller than 5%, and if you repeat that several times (think different strad forms or other instruments) the probability will go rapidly down... that would pretty much statistically prove that circle geometry and simple ratios of radii were at the origins of these shapes.

    "Will go rapidly down..". Yes that is exactly what's happen at the end of the Cremonese golden age - As soon as they start to build their form from existing ribs garland rather than an original mold 

    the decline is very quick more and more straight lines appears before the corners which is the sign of the increasing of a natural tendency of a bent rib