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Stringing up with a dry neck joint.


murrmac
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I am just curious to know if a perfectly fitted violin neck joint, prior to gluing,  would withstand the tension of the instrument being strung up to pitch.

 

I appreciate that this is probably not a common practice, but has anybody ever done it, even out of curiosity ? 

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I am just curious to know if a perfectly fitted violin neck joint, prior to gluing,  would withstand the tension of the instrument being strung up to pitch.

 

I appreciate that this is probably not a common practice, but has anybody ever done it, even out of curiosity ? 

Depends on how much of an interference fit the joint is.

My neck joints don't require any force to put in to place, so without glue, they will move just under the force of gravity.

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I have never strung up an instrument to test the joint but I did once shape the neck and discover half through the varnish schedule that I had never glued the joint. These days I don't fit necks that tight as I think it probably starves the joint somewhat and allowing for more expansion of the wood in the joint makes it stronger.

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Depends on how much of an interference fit the joint is.

My neck joints don't require any force to put in to place, so without glue, they will move just under the force of gravity.

David, I've been curious about this.  I fit my neck mortise for #1 with a shallow dove tail that held the neck in place quite securely with a dry fit (not glued).  It was a great deal of trouble for me, and took multiple efforts and eventually a repair before I got all contact surfaces chalk fitted.  The question (finally) should the mortise walls be straight or is the slight dove tail correct?

 

Thanks,

Jim

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I am just curious to know if a perfectly fitted violin neck joint, prior to gluing,  would withstand the tension of the instrument being strung up to pitch.

 

I appreciate that this is probably not a common practice, but has anybody ever done it, even out of curiosity ? 

 

If anyone has done it, Evan Smith would be the one.  I recall some discussion about this before.

 

I don't feel that much curiosity about testing the idea.  Without the shear strength of the glue at the button, it looks like a crappy way to hold a neck against the string forces trying to rotate the neck out of the mortise.  If it doesn't hold, I think you get the ribs ripped off of the block, or damaged in some way.

 

During the fitting process, I like to have it only tight enough to stay in place while I check the projection and overstand.  Lastly, I'll trim the sides of the mortise to get the fit where it requires no force to get into place.

 

Like David and Nathan, I'm not a fan of a tight dry fit. In aerospace bonding, the thickness of the bond line is very carefully controlled to a specific dimension.  Hide glue may act differently, but I'd rather not scrap/squeeze it all out.  Even more of a concern:  gluing up the surfaces and finding that the heel and button don't quite come together.  That happened once, and I don't want it to happen again.

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Interesting Dave, I have been making mine just on the not so tight side , just so it slips and grabs , I was making them real tight, then realized that the same action that necessitates some looseness between the top and neck heal might also benefit the neck mortise. one would hate to have a neck block split from shrinkage. Might have to loosen thing up even more. 

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I am just curious to know if a perfectly fitted violin neck joint, prior to gluing,  would withstand the tension of the instrument being strung up to pitch.

 

 

 

The short answer is YES. But it must be perfect. I discussed this a while ago but it irritated the amateurs. I won't make that mistake again.

A good structural engineer will work out for you what's going on. It is not mathematically trivial.

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The short answer is YES. But it must be perfect. I discussed this a while ago but it irritated the amateurs. I won't make that mistake again.

A good structural engineer will work out for you what's going on. It is not mathematically trivial.

Given some of the above discussion....a"perfect" joint might not.

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The short answer is YES. But it must be perfect. I discussed this a while ago but it irritated the amateurs. I won't make that mistake again.

A good structural engineer will work out for you what's going on. It is not mathematically trivial.

 

Yes, it's complicated, and depends on assumptions about friction (or not, depending on the angles at the joint), and perfect fit of rigid parts.  A good structural engineer would tell you that tiny variations in the assumptions would cause failure, and therefore you need to put thousands of dollars into a full-blown finite element model to get a better handle on the problem.

 

Or just use glue and forget about it.  :)

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Thanks to all responders ... I do get that a "perfectly fitting" joint in a violin neck joint is not the same thing as having the parts mate as tightly as humanly possible, and that glue enters into the equation.

 

But if the joint were to be made as tight as possible, then would I be correct in thinking that the flare of the neck and the corresponding flare in the mortise would be sufficient to withstand the string tension, at least for a short period ? I mean,  the neck wouldn't suddenly fly off during the tuning process,  would it?

 

Carl seems to think so,  unequivocally, so does everybody else concur?

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Thanks to all responders ... I do get that a "perfectly fitting" joint in a violin neck joint is not the same thing as having the parts mate as tightly as humanly possible, and that glue enters into the equation.

 

But if the joint were to be made as tight as possible, then would I be correct in thinking that the flare of the neck and the corresponding flare in the mortise would be sufficient to withstand the string tension, at least for a short period ? I mean,  the neck wouldn't suddenly fly off during the tuning process,  would it?

 

Carl seems to think so,  unequivocally, so does everybody else concur?

 

Don't worry about others "concurring". Means nothing. Look carefully and HARD to a cross section of the joint. IT'S A CAM.

( Old man Strad did fine without MN "concuring"  :lol: )

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Thanks to all responders ... I do get that a "perfectly fitting" joint in a violin neck joint is not the same thing as having the parts mate as tightly as humanly possible, and that glue enters into the equation.

 

But if the joint were to be made as tight as possible, then would I be correct in thinking that the flare of the neck and the corresponding flare in the mortise would be sufficient to withstand the string tension, at least for a short period ?

 

Yes, but with sufficient "crammage" :lol: , this can also be done with no flare, or even a reverse flare. I don't think the flare serves much function once the joint is glued. Should the glue fail, the slight dovetail might be enough to keep the neck from coming out completely, but I wouldn't expect it to retain the neck in the original position, given the plastic and flexible properties of wood, and the dimensional changes wood undergoes as the moisture content changes.

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Look carefully and HARD to a cross section of the joint. IT'S A CAM.

 

I looked at that, and determined the instant center of rotation.  To me, it looks like it will NOT hold unless you include friction, for normal geometry and no help from the side taper angles.  You'd need to change the usual 85-degree neck heel angle to about 120 degrees before it would become statically stable without friction.

 

( Old man Strad did fine without MN "concuring"   :lol: )

 

 

Also without a mortise and no cam.  He relied on glue and nails.  Mostly glue, I would wager.

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I was astonished to read that Stradivarius did not employ a mortise construction of any type, simply using a butt joint..

 

Are any of the Strads which are played today by concert artists still held together with glue and nails, or have they been reworked to a mortise and tenon construction?

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I looked at that, and determined the instant center of rotation.  To me, it looks like it will NOT hold unless you include friction, for normal geometry and no help from the side taper angles.  You'd need to change the usual 85-degree neck heel angle to about 120 degrees before it would become statically stable without friction.

 

 

 

Also without a mortise and no cam.  He relied on glue and nails.  Mostly glue, I would wager.

The glue and nails method seemed to work fine, up 'till the point that people started to realize that necks need periodic resets. The nailed method kind of fell down at that point.

 

For anyone who claims that a conventional violin can be strung up,  without glue, and without a "wedgie" fit of the neck (not to deny that wedgies might have extraneous interest for some people :lol: ), I will challenge you to show me even one example.

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...if the joint were to be made as tight as possible, then would I be correct in thinking that the flare of the neck and the corresponding flare in the mortise would be sufficient to withstand the string tension...

 

Yes, if the neck and the block were made from a sufficiently rigid and non-compressible material like steel.  But since they are made from wood, which I expect can be compressed and deformed when subject to the forces resulting from string tension, I would not want to try it for fear of causing damage, as Don Noon notes in post #5.

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If anyone has done it, Evan Smith would be the one.

 

 I recall some discussion about this before.I don't feel that much curiosity about testing the idea. Without the shear strength of the glue at the button, it looks like a crappy way to hold a neck against the string forces trying to rotate the neck out of the mortise. If it doesn't hold, I think you get the ribs ripped off of the block, or damaged in some way.

 

Sure I’ve done it, I be the one,,,blamed for everything,,,

 

Ed Campbell said  it would work ,,,so I tried it on Ed Campbell  and it did in fact work quite well,

(or so I thought)

I was expected to do some insane comic gag when least expected, so this time before  the banquet

I borrowed a German junker someone had there, and I clamped the neck on dry,,, strung it up,

Then took off the clamp,,. the neck didn’t move, and without any further proof I concluded wow! This does work!

I was in a raging hurry and I didn't look at the condition of the joint at all, I just remember it was narrow and deep.,,,so I detuned it a bit. Later that evening at the banquet I then  presented it to Ed to stand up in front of everyone and tune it for us, to which he  obliged. ( I was thinking WoW that neck is holding on better than I would have ever dreamed) The neck stayed on during this process and was in tune. However it was apparent that it was difficult to tune, but after going over it a few times Ed was successful,,,

So I get the evil eye and the shoulder shrug as to,, ,,,What the heck was that all about?

So I’m wildly playing on it and Ed’s watching me like,,,, where’s this going,,, and I ended up almost using it like a club before it came loose.

Ok! That’s funny,, ha ha,,now We were laughing.

And I erroneously believed for years that the strings held it in, due to the angles and leverage, ect.

It proved Ed was right.

That is wrong,,,,

After it came up on maestronet and there was much discussion, I went and really checked it out,

I tried it again fully expecting it to work again,,, and

No Way at all will that work under normal conditions,,

 

I was devastated for days, drank curdled milk and moldy bread in repentance for believing a lie.

 

Oh the shame!

 

The string pressure will not hold the neck on at all, even if the strings are down against the top plate edge

And running straight to the pegs on the outside of the box it won’t do it.

Though at that point it is getting close to equilibrium, but not quite far enough.

Like Don says the angle of the upper block  would have to change, dramatically.

However a tight fitting properly made neck joint will hold without glue, it is a dovetail after all, but the risk of cracking out is fairly great,

there is only a small bit of spruce and not much of a wedge,,,,

It would be fine made out of steel.....

I will add however that as the neck pulls off... the string tension pulls the neck up vertically and up

out of the joint as it pulls it out of the dovetail, the forces don't simply pry it straight out of the socket,

as it is coming off, it can only slide up at first movement, as in from the back plate tword the top plate..and this happens so fast ,, and the dovetail is so shallow it doesn't take much movement to clear the ribs.

 

So if the block and ribs do hold the pressure, it probably won't break anything if it comes out.

 

Why do you ask,,

 

The whole subject should be taboo.

 

I will never trust again,  well ,,,maybe Don.

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Mike Molnar is the one to ask regarding Campbell.

I've only fitted one neck... the chalk squeaked and the neck clicked as it seated. Was that too tight, too loose, or about right?

Actually I was Ed's little helper,

I was to keep the restless Indians happy on the night shift and help them with their projects.

His morning arrival and evening departure were as dependable as the sun.

Some of us come and go like the wind.

and Mike was there a few times too.

 

It was really good times,, very good times.

 

And yes that fit sounds about right if it has been sized and fitted after the glue has dried.

If that is the case, be sure to get the dried glue wet and hot before the final gluing,

it is possible to not get good adhesion between glue coats if the first coat is completely dry and not thoroughly reheated.

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Good Ed story Evan. Did the one about the school kids, the block of ebony, and the beaker of water, filter down to your generation? Next VSA.

I don;t remember that one, there were lots,,we did know how to have fun.

 

One year my hair was insanely long, down my back,  full very long beard, I was really ready to cut it,,

so I had a plan,,,I was always straining for some totally insane prank to pull,,,

Mary and I planned this,,Ed didn't even know about it,,,

 

About halfway through the banquet she gets up front and cleared her throat as only she can,

after everyone is looking like, what? more dirty jokes?

 

She calls me up and begins to ream my ass out as only she can do, I have to appear in shock and well you get it.

That hair has got to go!

Nasty dirty unkempt you look disgusting!

So she yanks out a chair and tells me to sit!

 

She is pissed!!!     You know Mary!

 

Ed's over there looking like,,,,,stunned,

 

She throws a sheet around me, (which I hold around my neck)

 

She gets the clippers and scissors(which I bought that afternoon)

and proceeds the whack my beard and hair off with the scissors, then grabs the electric shears and shaves my face,

while intermittently blazing out something about that I better shape up!

 

All the while she' keeps leaning over and whispering to me "I can't get these damn things to cut,"

"Slow down Mary don't push so hard, just a cut a little bit at a time,,, and DON'T CUT MY EARS!"

She's fumbling around scaring me half to death, waving those scissors around my face, of course she was a bit tipsy,,,,

and we both maintained our act perfectly.

I'd look out and see someone dying from laughter, and others were spell bound with horror, looks of pure shock and disbelief across their face.

 

The next morning there were not a few that were ready to console me for the horrific treatment that Bitch had subjected me to.

 

Mary and I laughed so hard we were crying,,,

 

Several years later guys were still coming up to me and telling me how sorry they were about that incident and couldn't  believe that it happened.

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After this one was through ,,Ed chuckled about it a lot..............

 

.

 

The remote control fart machine was securely taped to the bottom of Marys banquet chair, only I knew.

I mean this was a classy deal, some of the women made the dress of the evening the subject of the weeks efforts,

Even I had on shoes.

 

We were  almost finished with the salad and the talk had mostly faded, when suddenly,,

 

I pushed the button,

 

Mary's head jerked up and looked around, there was sudden and complete  silence in the room!

Ed in his stately and calm demeanor slowly rolled his head and caught Marys eye, she shook her head no.

Ed slowly looked back down and continued to eat.

 

a few minutes later, Quiet conversation had resumed,,

next attack,,,

The button,,,

sudden silence,,glances hither and thither,,,

 

Ed immediately did that little loop with his head right at Mary,,

she adamantly shook her head no,

Ed shook his head no, obviously a bit annoyed if Mary was guilty,,,

He certainly knew it wasn't him,,,and with a bit more stiffness and less dignity began to eat once more..

 

Things have now returned to normal, the soothing sounds of chewing and conversations once again filled the air,,,,

 

I can't help myself,,,

The button.

 

Instantly with laser precision and accuracy,,,,,,Mary shouts,,

 

EVAN!

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