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Curtate Cycloids. Again


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1 hour ago, Michael_Molnar said:

A curtate cycloid will fit some arches on some instruments. I think this is a futile attempt at force-fitting a design where it does not belong.

 

I saw Darnton slap a cycloid template on the back of a Strad and it fit pretty well.  However, after looking at a few Strads, I don't see that the tops are anywhere near a smooth mathematical curve, even allowing for distortion.  That's not to say that a cycloid-generated top shape would sound bad, it just wouldn't look like a Strad, and if top arching matters, then the chances of it sounding like a Strad may be reduced (although starting from zero, it might not be a noticeable reduction).

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1 hour ago, uncle duke said:

The only "old master" that I know of that checked arching with a hanging chain or thread is Ken.;)

 

With some luck Frank you may be able to make a set of arching templates for a violin before the holiday is through.

Here are some numbers you'll need for starters.

1.  31.5 or 32 for the c bout.

2.  2x the aforementioned 31.5 -32 for the lower bout.

3.  And 1.6, or if you follow Addie, 1.5 for the upper bout. 

Most templates sets use five templates for each plate.  Number 1 above would be template three, number 2 above would be template 5 and number three above would be template #1.

If I'm not mistaken you'll need to construct circles out of thin cardboard or plastic using the above numbers I put up above.  Those are in millimeters.  I can't find the discs I made or I would tell you more.  If I find one I'll be back with more info. or someone else can come help out too.  

The idea here is to get you started on your violin, get through with that and get you to the cello making that you want to do. 

Thank you very much for all the information. I have the Strad poster for the Messiah and plan on basing my #1 on that. I am "debating" with myself to make a "copy" or to make a "loosely based on". The based on sounds safer, then I can claim any differences are intentional :)

 

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If you spend some time looking at the various CAT scans of the violins of the old masters, the most notable consistency is that the transverse arch approaches the rib at right angles.  Darnton may have discovered the importance of this as the curtate cycloid enforces this automatically.

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4 hours ago, Roger Hill said:

...the transverse arch approaches the rib at right angles.  Darnton may have discovered the importance of this as the curtate cycloid enforces this automatically.

No, it doesn't.  It depends on the operator to specify what segment of cycloid to use.

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Yes.  You can find some instruments where some of the arching fits a CC quite well.  But as Don suggests, the family of classical archings does not generally fit CCs, only a limited subset of classical arching fits to a fair degree.   CCs are too specific to encompass the classical arching generally.

Now, that doesn't mean arching with CCs is bad.   But it does clearly mean that classical makers weren't using CCs to carve their arching.

 

Roger, what do you mean by approaching at right angles?  I'm not seeing what you mean.

 

 

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16 hours ago, David Beard said:

"Roger, what do you mean by approaching at right angles?  I'm not seeing what you mean."

 

First a definition:  the structural shape of the arch is the curve that is the centerline between the top and bottom of the plate in a transverse direction across the plate.  I call this the "arch shape" for short.  Now, go here  http://waddleviolins.com/index.php?contentID=120  and examine the arch shapes in the transverse sections shown for some notable violins and violas.  If you follow the arch shape line from any interior point along the line, you will at some point come to the edge, i.e. the point at which the top plate is glued to the lining.  This is the end of the arch.  as you approach the end of the arch,the angle between the rib and the arch shape line (extended) is very close to a right angle.

If you look at the various ct scan pictures available, you see this over and over.  The Strad 3D study that Sam Zygmuntowicz published has particulary good pictures of this. I am not suggesting that all the Cremonese arch shapes are curtate cycloids, they clearly are not.  What I am suggesting is that the old masters made an effort to have their arch shapes approach the ribs/linings at right angles to the rib.  If this is done, it leads very naturally to facilitation of breathing modes in which both the top and bottom plate edges force the rib tops and bottoms to move in the same direction, in and out, at the same time.  This is another way of saying the the top and bottom plates are not trying to twist the ribs in these modes.

Now, Michael Darnton discovered that he built better sounding violins when he started using curtate cycloid arch shapes.  My suggestion is that this is likely due to the enforcement of the right angle between arch shape and rib that quite naturally results if you use a curtate cycloid arch shape with the minimum of the CC close to the purfling line.  See  what  I mean?

 

16 hours ago, David Beard said:

 

 

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I wondered  what you  meant  too Roger.

I think this is  such an important feature, and seldom mentioned.  The other Roger pointed it out a while ago too, but it's not something I ever  learned in school. In order to achieve it the edges must be light, or the fluting sunk deep! I used to wonder had the under edge been planed away  over years when I  saw it in old  violins.

I asked in an old thread what Michael  Darnton saw in Cremonese violins, that defined the arching as Cremonese, that people  were missing. I wonder was this it.

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I've never heard it defined this way, so are we talking about the bottom of the channel?

At that point the arch,,, or the end of,,, is at 90o to the ribs. To accomplish it I often get deep with the fluting, sometimes a bit out of control,,as I am goal oriented, and the mess I leave on the way,,, just is. Though I have made a successful attempt to reverse that tendency,,It can be an enjoyable venture. I'm a digger.

I don't understand the big deal with curtate cycloids,,,they are just circles blended to the edges. Make an arch out of a circle, blend it into the channel and to the edge, and there it is, when it looks nice and natural it is most likely close to a cycloid. I've cut out a whole mess of circle templates and they fit all over the arching templets from the great and almighty Strad posters of the past, lengthwise and across. The trick is knowing when to straighten them out. Some arching in the upper and lower bouts are a small circle in the center and a lot of straight lines to the edges, quite flexible and certainly not a curtate cycloid, others are a circle all the way across. A bit stiffer on some fronts,, not a big deal really,, make a dozen or so and see what works . A general trend seems to be, the top arch runs closer to the edge, and the back plate arching has a bit more re curve around the edges.

I don't think the makers of old over thought it like I tend to do, I tend to make things much more complicated than they really are.

 

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5 minutes ago, FrankNichols said:

We should found a club, Over Thinking Anonymous". :)

I think that with minimal thinking you end up thinking that more thinking will make things better.  But at some point you need to make stuff and see how it really works.

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On 5/23/2017 at 11:26 AM, Peter K-G said:

This one is really close to CC all over 

59246f9c79e53_2014-11-0112_21_11.thumb.jpg.517d6461f955a0ddc30b8d8ac05a993c.jpg

5924708fd2ea2_2014-11-0112_18_28.thumb.jpg.edac7c50886855f69eff6b6154d732a6.jpg

59247092b8ae5_2014-11-0112_35_51.thumb.jpg.6e7a4e0717d7b0e183626b0e812c0942.jpg

I have seen a tendency for new makers to leave too much arch in the upper and lower bouts through the corners, peters photo give a good example of getting this area cleared out,, it leaves it flexible here, which is good,,, I've done a bunch this way, but it is not the only way. If curtate cycloids are used across the corners to see just what they look like here, and the rest of the arch is blended to match I think it is a good exercise to learn about extremes,,, as to remove this much wood for some makers would be like bungee jumping for the first time,,,,and for me will not be a first time! (bungee jumping that is!)

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8 minutes ago, Don Noon said:

I think that with minimal thinking you end up thinking that more thinking will make things better.  But at some point you need to make stuff and see how it really works.

That is the only thing that will produce any real understanding and knowledge, after the observation must come the experience.

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40 minutes ago, Don Noon said:

I think that with minimal thinking you end up thinking that more thinking will make things better.  But at some point you need to make stuff and see how it really works.

Well, the problem here is that A LOT of people made stuff and it didn't really work. More thinking might be in order. More so when one notices that Strads don't happen by accident - there should be some sparkle of Strads here and there, randomly. There isn't. Lots of good violins out there but very few capable of carrying BIG CONCERT with Berliner Ph. I believe this is something worth thinking about.

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1 minute ago, carl stross said:

Well, the problem here is that A LOT of people made stuff and it didn't really work. More thinking might be in order. More so when one notices that Strads don't happen by accident - there should be some sparkle of Strads here and there, randomly. There isn't. Lots of good violins out there but very few capable of carrying BIG CONCERT with Berliner Ph. I believe this is something worth thinking about.

Hmm, but isn't that what the recent study showed that in reality, new violins performed as well as the Strads when people didn't know which they were listening too?

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7 minutes ago, FrankNichols said:

Hmm, but isn't that what the recent study showed that in reality, new violins performed as well as the Strads when people didn't know which they were listening too?

No. The recent "study" showed that some non-descript group of people found that some carefully selected unknown modern violins performed ( within their ability to tell ) the same as some available unknown Strads. That's again, less than nothing. And some is not like 50 , it's like ... 3 or 4. The good Strads are NOT available for phony tests.

There are a lot of new violins better than some Strads - everybody knows this.

The previous study which was the subject of some heated debate on MN had major flaws. One, worked like this : you  test a drug on 10 patients. After 3 days they get better. 5 days better still. You disconnect the drug and...they die. You conclude the drug wasn't effective. When asked, you excuse yourself with " I did not have more time". 

Utter rubbish.

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Perhaps some who has not looked into it is not aware of that an arch based on curtate cycloids can vary considerably. For example by varying the shape of the long arch and the channel distance from the edge. 

Here are four tops made with cc:s. The two on the right have a lot fuller arching shapes.

IMG_20160821_143709.jpg

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1 hour ago, carl stross said:

Well, the problem here is that A LOT of people made stuff and it didn't really work. More thinking might be in order. More so when one notices that Strads don't happen by accident - there should be some sparkle of Strads here and there, randomly. There isn't.

Through what sort of process did you come to that conclusion?

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1 hour ago, carl stross said:

No. The recent "study" showed that some non-descript group of people found that some carefully selected unknown modern violins performed ( within their ability to tell ) the same as some available unknown Strads. That's again, less than nothing. And some is not like 50 , it's like ... 3 or 4. The good Strads are NOT available for phony tests.

How do you know which Stads were used?

I'm somewhat of an "industry insider", and even I don't know which Strads or moderns were used. Except that I know of one Strad used in one test, and also know that I did not personally submit any of my own instruments. (I think they want antiqued moderns, because the "welding goggles" used don't occlude all visual cues).

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5 minutes ago, David Burgess said:

How do you know which Stads were used?

I'm somewhat of an "industry insider", and even I don't know which Strads or moderns were used. Except that I know of one Strad used in one test, and also know that I did not personally submit any of my own instruments. (I think they want antiqued moderns, because the "welding goggles" used don't occlude all visual cues).

That's the problem - I don't know ! :)  Maybe they weren't Strads at all. Maybe they were "attributed" or "from the workshop". Maybe they knew Strad. Vaguely. Who knows ? When it comes to Fritz, anything is possible. I know for sure the "news" were specially selected and adjusted to an inch of their life. The "news" were not picked at random from the general population of "news". That would've been a disaster. Fritz didn't ask ME to submit one of my Chinese planks, masterfully tweaked by myself. :)  Why not ?

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