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Joint between upper block and neck /dovetail?

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On 4/21/2019 at 3:10 PM, jacobsaunders said:

You are full of shit (once again)

Could this be why the Bellosio button lasted unbroken for 240 years before JS and only 15 after?

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Glue does a pretty good job of holding things together, as anyone who's taken a neck out has seen. I'm sure the slight dovetail helps, but all of the failures that I have seen have been from a rotten fit with big fills of hard glue and from one repeat offender who makes a nice tight "dovetail" a complete lack of glue, from, I think, not sizing the wood and using fresh wood, to boot. The nice dovetail wasn't enough to do the job. I am aware of one violin with a "reverse" dovetail tightly fit but a perfect fit and good glue job, that's holding fine.

Years of being away from his homeland haven't dulled the precision of Jacob's English language skills, have they? :-)

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4 hours ago, Michael Darnton said:

Glue does a pretty good job of holding things together, as anyone who's taken a neck out has seen. I'm sure the slight dovetail helps, but all of the failures that I have seen have been from a rotten fit with big fills of hard glue and from one repeat offender who makes a nice tight "dovetail" a complete lack of glue, from, I think, not sizing the wood and using fresh wood, to boot. The nice dovetail wasn't enough to do the job. I am aware of one violin with a "reverse" dovetail tightly fit but a perfect fit and good glue job, that's holding fine.

Years of being away from his homeland haven't dulled the precision of Jacob's English language skills, have they? :-)

Yes, there are some pretty bad neck joints that do not come out.

No, I can’t say Jacob’s English skills are lacking.  I assumed they were lacking when he described no dovetail to a violin neck joint.....because I though that certainly he had to do a dovetail (a dovetail neck is pretty elementary).....but sure enough, his description was correct....the problem was not his English skills.

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18 minutes ago, Jerry Pasewicz said:

Yes, there are some pretty bad neck joints that do not come out.

No, I can’t say Jacob’s English skills are lacking.  I assumed they were lacking when he described no dovetail to a violin neck.....because I though that certainly he had to do a dovetail.....but sure enough, his description was correct....the problem was not his English skills.

Nathan was inaccurate recently, comparing you with Archie Bunker. Mr. Bean would have been more to the point.

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4 hours ago, jacobsaunders said:

Nathan was inaccurate recently, comparing you with Archie Bunker. Mr. Bean would have been more to the point.

 

So much for your English skills......he compared Rene’ to Archie Bunker, not me......Might be time for you to get some sleep...this is not getting any better for you, and right now you are your worst enemy..

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I was a cabinet maker before making violins. Dovetail joint as commonly understood is a mechanical joint. It locks together. The violin neck joint relies on glue to work. Maybe Jerry does dovetail joints on his necks, but it isn't common. And if his argument is that he gets to define dovetail joint to mean what he wants, well whatever.

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3 hours ago, bkwood said:

I was a cabinet maker before making violins. Dovetail joint as commonly understood is a mechanical joint. It locks together. The violin neck joint relies on glue to work. Maybe Jerry does dovetail joints on his necks, but it isn't common. And if his argument is that he gets to define dovetail joint to mean what he wants, well whatever.

Sorry, it is very common and considered good work.

No, that is not my argument; I am not defining dovetail, I am using the the accepted confirmed dictionary definition.  Why does “well whatever” always mean “I guess I was wrong but I can not admit it”? 

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I will give Jerry his due in that the Very Slight Taper of the heal does indeed result in a "dovetail" joint.... if, during the fitting the rib/block surfaces are "undercut" as carefully as the vertical V and the heal/button surface. Being a guitar builder I suppose I think of the guitar neck joint where the mortise sides are put into tension by the surrounding surface of the heal against the ribs [ no button here], making a secure mechanical joint with or without glue [although glue is the final component of both].

So some semantics.... some just plain degree.

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1 minute ago, Michael Jennings said:

I will give Jerry his due in that the Very Slight Taper of the heal does indeed result in a "dovetail" joint.... if, during the fitting the rib/block surfaces are "undercut" as carefully as the vertical V and the heal/button surface. Being a guitar builder I suppose I think of the guitar neck joint where the mortise sides are put into tension by the surrounding surface of the heal against the ribs [ no button here], making a secure mechanical joint with or without glue [although glue is the final component of both].

So some semantics.... some just plain degree.

Agreed, it is a matter of degree. 

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1 hour ago, Jerry Pasewicz said:

Agreed, it is a matter of degree. 

Just so I'm clear, do your neck joints hold together mechanically? Or are we dealing with semantics?

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29 minutes ago, bkwood said:

Just so I'm clear, do your neck joints hold together mechanically? Or are we dealing with semantics?

Yes.  The dovetail adds mechanical strength to the joint, this is not semantics.  The neck mortise is wider at the bottom than the top, matching the neck heel shape.

My apologies for being impatient.  As I mentioned earlier, this is especially important when working on older instruments.  Small inaccuracies can turn into big problems.

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The neck fit is technically a blind mortise and tenon joint.  The fact that it is a triangular tenon is irrelevant.  Ask any cabinet maker.  (You can ask my father if you dont know one yourself.)  A triangular tenon offer no material increase in strength over a straight tenon, other than a slight increase in glue surface.

A true dovetail joint would also look like a dovetail when viewed from above (flared outward)  and the neck could only be set by sliding the neck down into the top block.  Since the joint is mechanically locked in place, you would have a nearly impossible time removing it after gluing.  This is why cabinet makers use this joint for drawer faces.

If you used a strong wood for the top block, the mechanical locking means you would need no glue except at the button.

I have thought of trying this joint, but I think traditional top block materials are too weak to warrant a such a mechanically strong joint.  Also rather difficult to implement on a triangular tenon.

 

 

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6 minutes ago, Shunyata said:

A true dovetail joint would also look like a dovetail when viewed from above (flared outward)  and the neck could only be set by sliding the neck down into the top block. 

And so it does, albeit subtly as far as appearance, and only a very short distance as far as the sliding.  As to removal, I'll let those who reset necks tell you about saws and removing after gluing.  :) 

Also, a violin neck is not a 'tenon' by any definition I can find.  Tenons project, they have shoulders from wood being cut away from the main body.

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1 hour ago, Jerry Pasewicz said:

Yes.  The dovetail adds mechanical strength to the joint, this is not semantics.  The neck mortise is wider at the bottom than the top, matching the neck heel shape.

My apologies for being impatient.  As I mentioned earlier, this is especially important when working on older instruments.  Small inaccuracies can turn into big problems.

Yes you are correct Jerry. 

For those that don't get it or do it wrong the sides of the mortice are planed planed parallel to the sides of the FB so you do get a low angle dovetail ...I thought this was basic knowledge

 

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""Also, a violin neck is not a 'tenon' by any definition I can find.  Tenons project, they have shoulders from wood being cut away from the main body."

A tenon does not technically need to be collared the way you describe, although is often in in cabinetry to prevent wracking of frames.  The tenon heel is so large on a violin neck that it resists wracking naturally without collaring.

 

Edited by Shunyata
Correct typo

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I am amazed that any one can get so worked up over the definition of a dove tail joint.

My own understanding of the term dove tail is any joint where a tenon is wider at the bottom of the mortise than at the top which even if very slight adds considerable resistance to the tenon pulling out. The standard shouldered dove tail such as used on case work or drawer fronts is obviously going to be very strong because it would require large chunks of wood to be split off the mortised member in order to come out even if the glue should fail. The glue in that case is only to keep the joint from sliding apart in the reverse direction that it was assembled. On a violin neck the dove tail is so slight and the mortised member i.e. the block  so much softer than the maple of the neck that if the glue fails the neck can compress and or break the wood of the  block and come out often taking the button with it. While the button is unlikely to hold the neck by itself in the event of glue failure in the neck to block joint I am sure that it does help to strengthen the joint  against normal nontraumatic forces.

I have seen necks put in without the dovetail which lasted a long time due to good fitting and strong glue but which eventually failed when I think they might very well have held had the extra strength of even a slight  dove tail helped resist rotation of the neck in the joint.

I  also just wrote in another thread about having once finished carving the neck and button of a violin and then while varnishing realized the neck had never been glued after final fitting and was in fact held only by the slight dove tail and a tight fit. It is hard for me to imagine that it would not have loosened while being carved if it had no dove tail at all.

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2 hours ago, Shunyata said:

I have thought of trying this joint, but I think traditional top block materials are too weak to warrant a such a mechanically strong joint.  Also rather difficult to implement on a triangular tenon.

Agreed.. spruce, willow, box wood would not have the strength for a tight mechanical dovetail, the traditional wood with guitars is mahogany. A well fit, dry guitar dovetail takes mechanical assistance to separate and holds the tension of string at pitch. Ive heard it referred to as a double blind dovetail which is as you describe [v-shaped from both the vertical and horizontal]. there is also the fact that it is undercut vis a vi the shape of the heal so that the face of the heal exerts pressure on the ribs as the dovetail is pressed home creating a certain amount of clamping  pressure on the side faces of the dovetail joint.

That said with this traditional joint glue is always added to the final assembly. The joint can still be separated in the future, with the application of steam as I've done hundreds of times when resetting vintage necks.

The geometry and stresses on a guitar are different than arch topped instruments and over time the flattop guitar is trying to "fold itself in half".

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With regard to the joint that joins the neck to the body, I have a violin which has a broken button and loose neck. Although it is very loose and can be wiggled and moved ,the neck remains in the top block. Is this because it is not a tenon with parallel walls,or is it likely to have a very narrow angle dovetail ? Should it be possible to just wiggle and pull on the neck unto it leaves the body, or will it need to be slid up from its V-shape joint ?

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2 hours ago, Delabo said:

With regard to the joint that joins the neck to the body, I have a violin which has a broken button and loose neck. Although it is very loose and can be wiggled and moved ,the neck remains in the top block. Is this because it is not a tenon with parallel walls,or is it likely to have a very narrow angle dovetail ? Should it be possible to just wiggle and pull on the neck unto it leaves the body, or will it need to be slid up from its V-shape joint ?

A couple of things to check:

 *  As the neck is wiggling, are the ribs on either side moving with the neck?

 *  When looking through the endpin hole with light in the instrument, do you see anything irregular on the face of the upper block?

 

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1 hour ago, vathek said:

Does anyone have pics of the screws Strad used?

Strad used multiple ( I think three, but I just woke up) square nails. Stainer used one square nail. I use one 1.5" wood screw. 

Edit: I use the screws on baroque fiddles only. I mortise for modern. Though Ceruti was known to use screws on his "modern" (I'd say transitional) necks.

 

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It took me a minute to figure out what the point of contention was here.  So the angle of the mortice walls should match the angle of the fingerboard like so..

7B5200EF-FC7A-43C0-ACA1-21AB11BF375E.thumb.jpeg.c04c5f8c89e3c048e247e340bec03a99.jpeg

Honestly, this is not something I’d really considered but now it seems like common sense. 

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I am reminded of the sour faculty joke that academic disputes are so bitter because the stakes are so small.

I also have a personal angle on this topic.  One of my fiddles, reportedly made by a Norwegian immigrant, needed its neck replaced eventually.  A thoughtful band-mate, in a moment of carelessness,  broke the neck off for me, and revealed a genuine guitar-type dovetail.  Had I tried the usual "karate chop" removal technique, the results would have been catastrophic.  (I very earnestly hope I don't ignite a dispute over the karate chop method).

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1 hour ago, JacksonMaberry said:

Strad used multiple ( I think three, but I just woke up) square nails. Stainer used one square nail. I use one 1.5" wood screw. 

Edit: I use the screws on baroque fiddles only. I mortise for modern. Though Ceruti was known to use screws on his "modern" (I'd say transitional) necks.

 

I hope you use stainless steel screws (or nails, for that matter). I say this from actual experience with old instruments with screwed on necks.

This happens with violins, too: https://www.ipwea.org/blogs/intouch/2016/02/10/the-hidden-cost-of-concrete-corrosion

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