finnfinnviolin

Determine arching height

Recommended Posts

I would like to raise the topic of how to determine arching height, we know that most strads are in the 15-16 mm range with the back being around .5 or so lower, and Del gesus being slightly lower but with similar range between the front and the back. 

 

We also know that that the top arch will raise by around 1mm over time. 

 

How does one one determine the set heights? 

 

And is is it worth compensating for the 1mm raise when working the belly? Do any of you do this? For example if you are making a bench copy and you want the heights to be the same as the original perhaps compensating in the making process could help with achieving the same finished heights

 

Perhaps its it’s a good idea to start with the arching the same height for the top and the back allowing for the raise on the top. Putting a spring in the bar could also affect this. 

 

Is is there some kind of overall thickness of the entire violin that we should be aiming for? Tops back and ribs, and is there any kind of formula that repeats itself in classical work? Regardless of whether the top or the back is higher. 

Share this post


Link to post
Share on other sites

So in that case your back would be higher than the belly, Given that your back is thicker. If your method is based on classical methods Then why are the classical instruments generally higher on the top? 

 

What makes you say the classical instrument are the same when the arching says otherwise? 

1 minute ago, Torbjörn Zethelius said:

Like the classical Italians I make the inside archings equally high in belly and back, and don't compensate for future distorsion because it's impossible to predict. If you want the belly to distort less, simply make it thicker.

 

Share this post


Link to post
Share on other sites
12 hours ago, finnfinnviolin said:

And is is it worth compensating for the 1mm raise when working the belly? Do any of you do this? For example if you are making a bench copy and you want the heights to be the same as the original perhaps compensating in the making process could help with achieving the same finished heights

 

Perhaps its it’s a good idea to start with the arching the same height for the top and the back allowing for the raise on the top. Putting a spring in the bar could also affect this. 

 

3 minutes ago, finnfinnviolin said:

So in that case your back would be higher than the belly, Given that your back is thicker. If your method is based on classical methods Then why are the classical instruments generally higher on the top? 

 

What makes you say the classical instrument are the same when the arching says otherwise? 

 

You can figure this out for yourself. ;) Or, read my article 'Arching the divide'.

Share this post


Link to post
Share on other sites

 The inside arches are not the same,  You can see that in CT scans.   That doesn't mean they didn't do the inside first.  They could have but then why is there a hollowed out plate holder.  Anyway the CT scans reveal something about arching and thicknessing if you look carefully.  

Share this post


Link to post
Share on other sites
1 hour ago, nathan slobodkin said:

Classical instruments do not always have lower backs than tops.  For example Joey the kid Guarneri's cellos can have radically higher backs than fronts.

Absolutely there are definitely some instruments that are higher on the back, but I would say that if you made an average it would show the top being higher 

Share this post


Link to post
Share on other sites
4 hours ago, finnfinnviolin said:

I would like to, where can I find your article?

https://www.dropbox.com/s/k5qr1ez8mei3xx7/arching_the_divide.pdf?dl=0

 I would add that the famous French l’encyclopedie  compiled by Diderot also states that the internal archings were made before the outsides. It makes total sense if you think about it. 

3 hours ago, MikeC said:

 The inside arches are not the same,  You can see that in CT scans.   That doesn't mean they didn't do the inside first.  They could have but then why is there a hollowed out plate holder.  Anyway the CT scans reveal something about arching and thicknessing if you look carefully.  

 What’s a plate holder? :) The vast majority  of classical instruments have similar internal archings in both belly and back. It’s true that  some instruments have an internal hump in the back, but I would say that it’s the exception from the rule. And besides, who knows what these instruments have been through over the centuries. 

Share this post


Link to post
Share on other sites

I think the thickness bulge on the inside seems to be more the rule.  The Titian comes to mind since I have copies of that. But I've seen it on others also.  I think I see a pattern.    Plate holder I mean the cradle in the museum in Cremona,  what ever it's called.  If it really was Strad's.    Obviously in use the plate would be arched on the outside while the inside is being worked on.  My guess is they didn't finish one side then work the other.  They probably worked both sides before it was finally finished.  

 

Strad Cradle.png

Share this post


Link to post
Share on other sites
7 hours ago, MikeC said:

I think the thickness bulge on the inside seems to be more the rule.  The Titian comes to mind since I have copies of that. But I've seen it on others also.  I think I see a pattern.    Plate holder I mean the cradle in the museum in Cremona,  what ever it's called.  If it really was Strad's.    Obviously in use the plate would be arched on the outside while the inside is being worked on.  My guess is they didn't finish one side then work the other.  They probably worked both sides before it was finally finished.  

 

Strad Cradle.png

This is indeed a strong argument pro outside first. If they would have done it the other way round, this tool would be unnecessary. I do the purfling on the closed box and never clamp the box into the cradle during the purfling.

There are mainly four methods of determining arching height I am familiar with:

- Geometrical derived, based on measured wood properties

- acoustical methods based on local tap tones or plate modes

- a fixed height, mostly developed on empirical basis.

- just copying a certain violin up to the last tenth of millimeter

For the cremonese school, the last two are certainly excluded, but it still leaves a lot of space for speculation. A lot of methods may work quite well. What I observe is that no matter which method is used by a certain maker, almost everyone claims that he has found "the one" with the main two arguments always repeating: It seems to work in some way and was "invented" by the respective maker. 

IMHO it might be enough to find a good method which produces consistent results and not to worry too much about history because it’s a game that you can’t win.

Share this post


Link to post
Share on other sites
9 hours ago, MikeC said:

I think the thickness bulge on the inside seems to be more the rule.  The Titian comes to mind since I have copies of that. But I've seen it on others also.  I think I see a pattern.    Plate holder I mean the cradle in the museum in Cremona,  what ever it's called.  If it really was Strad's.    Obviously in use the plate would be arched on the outside while the inside is being worked on.  My guess is they didn't finish one side then work the other.  They probably worked both sides before it was finally finished.  

 

Strad Cradle.png

 

2 hours ago, Michael Szyper said:

This is indeed a strong argument pro outside first. If they would have done it the other way round, this tool would be unnecessary. I do the purfling on the closed box and never clamp the box into the cradle during the purfling.

There are mainly four methods of determining arching height I am familiar with:

- Geometrical derived, based on measured wood properties

- acoustical methods based on local tap tones or plate modes

- a fixed height, mostly developed on empirical basis.

- just copying a certain violin up to the last tenth of millimeter

For the cremonese school, the last two are certainly excluded, but it still leaves a lot of space for speculation. A lot of methods may work quite well. What I observe is that no matter which method is used by a certain maker, almost everyone claims that he has found "the one" with the main two arguments always repeating: It seems to work in some way and was "invented" by the respective maker. 

IMHO it might be enough to find a good method which produces consistent results and not to worry too much about history because it’s a game that you can’t win.

It could also have been a cradle for set up work, laying in purfling, etc.

Share this post


Link to post
Share on other sites

It is commonly accepted that the Cremonese laid in their purfling after the body was glued up and the neck attached. For that you need a cradle like the one in the photo. Since baroque necks were level with the edge of the belly, they wouldn't be in the way, like a modern neck would be. The central hole allows for it to swivel, and that is exactly what you need when you lay in the purfling.

 

Share this post


Link to post
Share on other sites
1 hour ago, Torbjörn Zethelius said:

It is commonly accepted that the Cremonese laid in their purfling after the body was glued up and the neck attached. For that you need a cradle like the one in the photo. Since baroque necks were level with the edge of the belly, they wouldn't be in the way, like a modern neck would be. The central hole allows for it to swivel, and that is exactly what you need when you lay in the purfling.

 

Torbjorn,

I  always imagined the Cremonese using this type of cradle while purfling. However there was an excellent discussion of this here on MN some years ago where some of our (Newark trained?) colleagues posted pictures of the tool they use for purfling the closed box which looked totally different from anything I had seen before and not only had control of distance to edge measurements but also held the knife parallel to the rib surface and controlled depth as well. This could easily (most easily?) be used with the corpus in ones lap and a great deal of force being used to cut the channel full depth with little risk of slipping or other problems. I was pretty blown away by the ingenuity of the tool and am sure that purfling in that way is much easier and faster than other methods and more easily learned as well.

I am still purfling before closing the way I was originally taught but If I ever have an apprentice they will be making me one of those tools.

Share this post


Link to post
Share on other sites
1 hour ago, nathan slobodkin said:

Torbjorn,

I  always imagined the Cremonese using this type of cradle while purfling. However there was an excellent discussion of this here on MN some years ago where some of our (Newark trained?) colleagues posted pictures of the tool they use for purfling the closed box which looked totally different from anything I had seen before and not only had control of distance to edge measurements but also held the knife parallel to the rib surface and controlled depth as well. This could easily (most easily?) be used with the corpus in ones lap and a great deal of force being used to cut the channel full depth with little risk of slipping or other problems. I was pretty blown away by the ingenuity of the tool and am sure that purfling in that way is much easier and faster than other methods and more easily learned as well.

I am still purfling before closing the way I was originally taught but If I ever have an apprentice they will be making me one of those tools.

Nathan,

Here's one of two home made purfling knives along with the cradle I use for purfling the box, and a photo of me cutting the channel. I can't imagine how one could hold the box in ones lap while cutting the channel. You want the box to lay flat on the bench so the knife can be held upright. That gives the most control, I think. Also, the extra long handle helps to keep it upright.

IMG_3266.thumb.JPG.253e4dde15b71f8dcc67246d1ecd5e34.JPGIMG_3402.thumb.JPG.a36a8fe690a59de7340ddbc88bae0681.JPGIMG_3964.thumb.JPG.681510222e71a31b4613ea8af5ab361e.JPG

Share this post


Link to post
Share on other sites
14 hours ago, Torbjörn Zethelius said:

I would add that the famous French l’encyclopedie  compiled by Diderot also states that the internal archings were made before the outsides. It makes total sense if you think about it. 

Thought about it.

Doesn't make sense to me.  At all.

But whatever you like, do that.

Share this post


Link to post
Share on other sites
6 hours ago, Michael Szyper said:

 A lot of methods may work quite well. What I observe is that no matter which method is used by a certain maker, almost everyone claims that he has found "the one" with the main two arguments always repeating: It seems to work in some way and was "invented" by the respective maker. 

IMHO it might be enough to find a good method which produces consistent results and not to worry too much about history because it’s a game that you can’t win.

Everyone has a favorite tree to bark up!   :D

Share this post


Link to post
Share on other sites
4 hours ago, Torbjörn Zethelius said:

 

It could also have been a cradle for set up work, laying in purfling, etc.

you don't put purfling on the inside of the plate,  but yeah it could be holding plates while gluing in a base bar or something,   Someone was certainly working on the inside while the outside was arched.  

Pivoting on a central hole is also exactly what you need when carving cross arches.  

Share this post


Link to post
Share on other sites

Speaking of Cremonese construction methods.  It's accepted that they put in the purfling after the box is closed.   I assume they carved the recurve channel after attaching the neck but before putting on the finger board because it goes under the finger board.  But they put the purfling in after attaching the finger board because the purfling stops there.   Would that be right?    Also in CT scans the purfling is  not always straight up and down parallel with the ribs,  it seems to be angled a bit.  So why is that? 

Sorry, getting way off topic,  never mind.  

Share this post


Link to post
Share on other sites

It's very impossible to see same arching style (longitudinal) for top and back on old cremonese violins. I can only see that many tops where intentionally made straighter in the middle, sometimes stretching a long way to the near the end blocks, with a close curve.

Share this post


Link to post
Share on other sites
1 hour ago, MikeC said:

Speaking of Cremonese construction methods.  It's accepted that they put in the purfling after the box is closed.   I assume they carved the recurve channel after attaching the neck but before putting on the finger board because it goes under the finger board.  But they put the purfling in after attaching the finger board because the purfling stops there.   Would that be right?    Also in CT scans the purfling is  not always straight up and down parallel with the ribs,  it seems to be angled a bit.  So why is that? 

Sorry, getting way off topic,  never mind.  

Probably purfled after the top is glued to the ribs to which the neck is already joined but before the fingerboard goes on. The purfling goes past the neck but doesn’t join up. 

Share this post


Link to post
Share on other sites
2 hours ago, Don Noon said:

Thought about it.

Doesn't make sense to me.  At all.

But whatever you like, do that.

 

Yes, yes, and yes.

 

21 minutes ago, Peter K-G said:

It's very impossible to see same arching style (longitudinal) for top and back on old cremonese violins. I can only see that many tops where intentionally made straighter in the middle, sometimes stretching a long way to the near the end blocks, with a close curve.

:)

Share this post


Link to post
Share on other sites
9 hours ago, Michael Szyper said:

There are mainly four methods of determining arching height I am familiar with:

- Geometrical derived, based on measured wood properties

 - acoustical methods based on local tap tones or plate modes

 - a fixed height, mostly developed on empirical basis.

 - just copying a certain violin up to the last tenth of millimeter

Seems like the cradle would be more useful for hollowing... but having done purfling after closing the box many times as torbjorn mentions it’s very hard to do without a cradle so The cradle could absolutely be used just for purfling/setup purposes.

 

but there Are definitely some holes in this theory as it regards to the arching heights we see now.

 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.