Jump to content
Maestronet Forums

Rib Taper--why not from the back?


marinosglitsos

Recommended Posts

Because spruce is so much weaker across the grain than along it clamping the center top of the plate to a lower block does not cause an upward bending force in the center of the plate. Instead it simply bends the center arch slightly flatter across the grain. A back which is bent by gluing to a shorter top block creates an upward force in the center of the plate and a backward force at the neck heel as the back which is fairly non directional in it's stiffness tries to return to equilibrium. This causes a resistance to the pressure of the sound post toward the back as well as a resistance to the neck rotating downward. Both of these are beneficial in resisting the common deformations which start to occur as soon as the instrument is set up. I was taught by people trained at the Cremona school in the late 70's early 80's to taper the back only.

Hi Nathan,

 

How were the ribs tapered? From the upper corner blocks to the neck block or did the taper run the whole length of the back? There are different schools of thought on this and much depends upon by whom the people were "trained in Cremona" and classical Cremonese violinmaking. For sure nobody was thinking a lot about Stradivari until Giuseppe Fiorini and Simone Fernando Sacconi made their contributions to Cremona. Today, there is no one rigid system taught in Cremona. For example you can find, visiting various shops; inside form, outside form, one piece forms, three piece forms, no form etc.; spirit varnish, oil varnish, essence varnish, synthetic varnish; natural colors, synthetic colors; varnish applied with the hand, with a pad, with a brush, with a mouth sprayer or by compressed air; the idea violins should be made of relatively fresh wood (like Guarneri 'del Gesù' fronts) versus those who use older more seasoned wood; the list goes on. The point is that it is difficult to affirm this is how it is taught in Cremona.

 

I'm with Roger on digging as deeply as I can into the classical Cremonese methods and techniques and I try to keep it separate from other ideas and theories, as worthy as they may be.

 

Bruce

 

P.S. (off the subject) There was a beautiful Pietro Giacomo Rogeri cello featured in the Strad not so long ago that came complete with the poster. It comes through the shop on occasion if you need further info but the poster is pretty complete.

Link to comment
Share on other sites

  • Replies 57
  • Created
  • Last Reply

Top Posters In This Topic

Interestingly enough, the old instruments I have had apart for restoration, including Stradivari, Guarneri 'del Gesù' and other classic Cremonese makers, no longer have any spring in the upper bouts, either on the top or the back. They usually fit together neatly without any real pushing and shoving necessary (even though some of these instruments have maintained the original difference between the smaller neck block height in relation to the other five blocks). This type of springing is fairly docile which, in time, relaxes and becomes insignificant relative to other forms of instrument deformation and creep.

 

On instruments I make, the taper is 1/2 on the belly side and 1/2 on the back.

 

Bruce

 

Hi Bruce,

 

Thank you for this valuable information, I've always thought it was so, but it is important to have confirmation from direct observations.

 

My conclusion about the belly ribs taper is that it serves for compensate the body deformation induced by string tension, to avoid ending up with the plane of ribs concave.

This is very bad from aesthetic point of view but I also think that it has a negative effect on sound.

So I do my ribs taper about 1.3/1.5 mm on belly side and about 0.7/0.5 mm on back side starting from upper corner blocks, matching the 2 mm difference of Strad compass arcs on the original forms.

2 mm on belly side only seems too much tension for me and so I compensate on the other side, adapting the ribs to the back planed surface that I make slightly concave.

 

 

Davide

Link to comment
Share on other sites

 

How were the ribs tapered? From the upper corner blocks to the neck block or did the taper run the whole length of the back? There are different schools of thought on this and much depends upon by whom the people were "trained in Cremona" and classical Cremonese violinmaking. For sure nobody was thinking a lot about Stradivari until Giuseppe Fiorini and Simone Fernando Sacconi made their contributions to Cremona. Today, there is no one rigid system taught in Cremona. For example you can find, visiting various shops; inside form, outside form, one piece forms, three piece forms, no form etc.; spirit varnish, oil varnish, essence varnish, synthetic varnish; natural colors, synthetic colors; varnish applied with the hand, with a pad, with a brush, with a mouth sprayer or by compressed air; the idea violins should be made of relatively fresh wood (like Guarneri 'del Gesù' fronts) versus those who use older more seasoned wood; the list goes on. The point is that it is difficult to affirm this is how it is taught in Cremona.

 

I'm with Roger on digging as deeply as I can into the classical Cremonese methods and techniques and I try to keep it separate from other ideas and theories, as worthy as they may be.

 

As a Cremona maker I fully agree with these statements and this is what I recommend to all students of violin making with which I come into contact.

There are too many makers today in Cremona to establish a single line of thought, for better or for worse....... :rolleyes:

 

Davide

Link to comment
Share on other sites

Hi Nathan,

 

How were the ribs tapered? From the upper corner blocks to the neck block or did the taper run the whole length of the back? There are different schools of thought on this and much depends upon by whom the people were "trained in Cremona" and classical Cremonese violinmaking. For sure nobody was thinking a lot about Stradivari until Giuseppe Fiorini and Simone Fernando Sacconi made their contributions to Cremona. Today, there is no one rigid system taught in Cremona. For example you can find, visiting various shops; inside form, outside form, one piece forms, three piece forms, no form etc.; spirit varnish, oil varnish, essence varnish, synthetic varnish; natural colors, synthetic colors; varnish applied with the hand, with a pad, with a brush, with a mouth sprayer or by compressed air; the idea violins should be made of relatively fresh wood (like Guarneri 'del Gesù' fronts) versus those who use older more seasoned wood; the list goes on. The point is that it is difficult to affirm this is how it is taught in Cremona.

 

I'm with Roger on digging as deeply as I can into the classical Cremonese methods and techniques and I try to keep it separate from other ideas and theories, as worthy as they may be.

 

Bruce

 

P.S. (off the subject) There was a beautiful Pietro Giacomo Rogeri cello featured in the Strad not so long ago that came complete with the poster. It comes through the shop on occasion if you need further info but the poster is pretty complete.

Bruce

I use a lower top block only. If the taper was from the lower block to the upper there would be no bending forces involved.

The Cremona trained guys I learned from were Will Whedbee and Tetsuo Matsuda. I don't know who their teachers were but don't beleive they were the same. I know Tetsuo worked for several people there after finishing school.

Also on the other subject of small cellos, thanks for the info on the Rogeri I'll look it up. Do you happen to know the answer to my question of whether J.B.Guad made increasingly higher cello ribs over time? Maybe you could answer on the Guad cello thread if you do.

Link to comment
Share on other sites

Most cellos have about 5mm of taper from the upper corners to the top block

Is that on the top plate surface of the ribs, or is it on the back plate surface of the ribs, or both?

Does it vary with every instrument or every maker?

I am wondering if tapering rules apply to all of the bowed instrument family.

Thanks

Link to comment
Share on other sites

How much rib taper is there on a Strad cello?

Can it be seen more easily?

Would a cello be taoered differently from a violin, under the chin vs. between the legs?

Sacconi, on a copy of one of his cello drawings that I have of a forma B model gives the rib heights of 12.9 cm. and 12.2 cm. That would make 7 mm. but on actual instruments I have never seen that much difference. It's usually closer to Nathan's 5 mm. and sometimes less. Using the observations from actual instruments, that have been opened and closed on numerous occasions and for one reason or another modified may not be totally reliable but many have the five blocks very near the same height and the neck block decidedly smaller. I think the 7 millimeters suggested by Sacconi represents his idea of how a cello would be just completed by Stradivari.

 

The actual taper is not at all easy to detect on old instruments that have a certain amount of deformation and have been repaired and disassembled a number of times. At any rate the taper is there as described, in reasonably well preserved Cremonese instruments, be they violins, violas, cellos, guitars, violas d'amore, violas da gamba or pochettes; just to name a few.

 

Bruce

Link to comment
Share on other sites

'' So far, the discussions all assume that once you glue the back and ribs together flat, they stay that way when you bend the top to the non-flat upper rib face. ''

When I make a new instrument I sand the gluing surface of the back and ribs on a large sanding board, flat.
Then when the ribs are glued onto the back, I sand the gluing surfaces of ribs and front flat.
So yes, you can ensure it's all flat and square. 
I taper the ribs from the lower to upper block in a flat line for this reason. 


 

Link to comment
Share on other sites

  • 9 years later...

Don’t mean resurrect the dead with this thread.. but I’m wondering.. a. What the thoughts on this topic are with reference to the vid link and b. if any one knows what form is being used?

https://m.youtube.com/watch?v=KUz6m-97ce4&pp=ygURa2V2aW4gbGVlIGx1dGhpZXI%3D
 

time stamp around 6 mins when he gets into the science of the tapper..

Link to comment
Share on other sites

 

I’ll try reaching out to him.. there were questions in the vid comments of ppl asking for details about the form and he points out in the vid that he found the form in a manuscript..but I didn’t see much for a response from him on that specifically.. I was thinking maybe because it’s so unorthodox lol.. but I do like technical explanation for the taper and the effect on the sound.. I thought that was interesting.

 

this thread is almost 10yrs old.. I’m wondering if opinions and techniques have changed on the taper.. top vs bottom.. top bows only vs full body length taper.. 

what insights have been gained if any since this thread was hot?

 

Link to comment
Share on other sites

10 hours ago, JonGeo said:

this thread is almost 10yrs old.. I’m wondering if opinions and techniques have changed on the taper.. top vs bottom.. top bows only vs full body length taper.. 

what insights have been gained if any since this thread was hot?

I haven't changed my mind, I still think the same as 10 years ago regarding this taper, I haven't had any new evidence that could make me change my mind

Link to comment
Share on other sites

On 11/29/2023 at 11:03 AM, JonGeo said:

Don’t mean resurrect the dead with this thread.. but I’m wondering.. a. What the thoughts on this topic are with reference to the vid link

https://m.youtube.com/watch?v=KUz6m-97ce4&pp=ygURa2V2aW4gbGVlIGx1dGhpZXI%3D

My thoughts are,
Oh mercy mercy me, oh my gawd, and shiver me timbers! :lol:
And I think he would be the ideal person to ask, "How much starch can one apply to ones skivvies before it starts to flake off ?" :D

Link to comment
Share on other sites

6 hours ago, Bill Yacey said:

I would argue that this is done for visual aesthetics. It's such a subtle taper that most people wouldn't notice it unless it was pointed out to them.

I disagree respectfully, imo the taper serves two purposes, one it acts somewhat like a "counter deformer" somewhat how the recurve acts like a curved brim on a hat that keeps it from deforming, it "fights back against the string tension" and the desire for the pegs to "kiss" the end pin, if suddenly it was made from clay {fold in half}

and perhaps more importantly it creates a weight and structural shape gradient somewhat like a pyramid or a flagpole which prevents/reduces unwanted pegbox/scroll undulation under intense bowing, or more precisely, it makes the structure more rigid where it matters

Link to comment
Share on other sites

On 11/30/2023 at 1:38 AM, JonGeo said:

this thread is almost 10yrs old.. I’m wondering if opinions and techniques have changed on the taper.. top vs bottom.. top bows only vs full body length taper.. 

Just a sidenote to this: 

I think there were also a few makers in old Cremona who did not taper the ribs. If my memory is correct Carlo Bergonzi was one of them.

Link to comment
Share on other sites

21 hours ago, jezzupe said:

I disagree respectfully, imo the taper serves two purposes, one it acts somewhat like a "counter deformer" somewhat how the recurve acts like a curved brim on a hat that keeps it from deforming, it "fights back against the string tension" and the desire for the pegs to "kiss" the end pin, if suddenly it was made from clay {fold in half}

and perhaps more importantly it creates a weight and structural shape gradient somewhat like a pyramid or a flagpole which prevents/reduces unwanted pegbox/scroll undulation under intense bowing, or more precisely, it makes the structure more rigid where it matters

Well, then I guess we are in agreeance. If anything, I believe it may serve a physical purpose as you describe. Visually,  it's very subtle as I described in my previous post.

Link to comment
Share on other sites

1 hour ago, Bill Yacey said:

Well, then I guess we are in agreeance. If anything, I believe it may serve a physical purpose as you describe. Visually,  it's very subtle as I described in my previous post.

Yes, very subtle, generally have to stare for a moment, following the contours of the lines

Link to comment
Share on other sites

That mark makes no sense.  If you follow it in a straight line to the corner block it will be below where the top is glued to the corner.   If it went from the corner block to the lower neck block then it should be at the glue line and not visible.  

Link to comment
Share on other sites

I find this all very interesting.. though there seems to be some consideration for sound given to the taper (see previous post… Kevin Lee’s vid and the time stamp.. unless you want to watch the whole vid…) it seems to me to be primarily an engineering consideration.
 

I was watching a video on YouTube months ago on a titian build which the builder pointed out a taper on the bottom side at the lower bout. I think the plans he showed was the titian which would make sense, since that was what he was building.. but for some reason I thought it was a messiah plan he showed. I can’t for the life of me find that video now.. and it looks like he’s taken a number of his videos down… probably behind a paywall seeing as he has an online violin building course now.

anyhow.. I’m sure I wasn’t seeing things when I watched this.. possible misunderstanding? Anyone have the plans of those two builds that could verify that.

I’m really enjoying the input people are giving here.. learning so much.. thanks

Link to comment
Share on other sites

2 hours ago, MikeC said:

That mark makes no sense.  If you follow it in a straight line to the corner block it will be below where the top is glued to the corner.   If it went from the corner block to the lower neck block then it should be at the glue line and not visible.  

Hmm...it makes perfect sense to me. When you have the ribs at full height (without the taper yet), draw a line with a scribe marker with the measurement of the taper at the upper block (about 2 mm), and use it as a reference to reach when planing the taper. Well, I would have just made it shorter to let it disappear, but having it longer gives a reference for the inclination of the ribs outside the upper block. The same line is also visible on some Amati instruments.

Link to comment
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.



×
×
  • Create New...