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Woodland

Boxy, honky nasal sound.

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2 hours ago, Delabo said:

Perhaps I did not make myself clear.

As the upstand increases then the bridge has to be higher which in turn increases the string length. If we take the A string it is still an A string but over a longer distance. It would then have to be tuned down to achieve 440 hz.

No, the same A string, spanning a longer distance, at the same tension, would need to be tuned up to achieve a 440 A.

Thank you for your patience. Many things in the mechanical physics realm fall easily into place for me, but I would also like to do much better at explaining things to those for whom it does not.

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2 hours ago, martin swan said:

What Edi has just contributed seems salient - that the pivot point is actually some way down the neck joint rather than right at the top of it.

I don't agree that Edi's example of the breakage point in the cello neck/heel says anything about the "pivot point".

My nail puller has the greatest range of movement (~ = most likely point of breakage) where the nail is engaged, but the pivot point is several inches away. And it is much easier to pull the nail out when the lever is closer to horizontal than when it is closer to vertical (torque).

Sotto voce: Some of this thread brings back bad memories. I was crap at applied mathematics, but good at pure mathematics, so could not calculate where the projectile was going to land - sad.

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1 minute ago, Janito said:

 And it is much easier to pull the nail out when the lever is closer to horizontal than when it is closer to vertical (torque).

But the nail is half out :)

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3 hours ago, Jerry Pasewicz said:

Not to worry Martin, the numbers we are talking about and the concepts are not radical or different than what has been in practice for a century.  The drawings and measurements I have on my desk right now show the Betts with an appui on the G side at 6.5 and on the E side at 6.8.  These concepts have been around for a very long time, this discussion for me has been to figure out why these things work, not if they would make a difference.

The Betts Stradivari?

Very bad example for me - that violin is ruined.

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13 minutes ago, martin swan said:

The Betts Stradivari?

Very bad example for me - that violin is ruined.

Okay, take your pick and do the math.  The point being, this is nothing new, it has been evolving forever, and today’s professional restorers are the most conservation minded ever in history.....we got this.

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1 hour ago, martin swan said:

The Betts Stradivari?

Very bad example for me - that violin is ruined.

How so? I've played, and spent some time examining that fiddle, and that wasn't my impression at all.

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4 hours ago, Janito said:

I don't agree that Edi's example of the breakage point in the cello neck/heel says anything about the "pivot point".

As long as this thread's meandering all over the place,

Where and how do cello necks break?

- Do the heels split, and the neck immediately falls out?

-Do the heels split, but only drop in projection slightly yet remain glued in the mortise?

-Do the heels split, but not much change in projection right away?

(I'm interested in those that break with no immediate trauma as the cause)

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Don,

I don't believe I have ever seen one split without some trauma. They usually break on a line with the back of the neck or a bit lower.  Instruments with a higher apuis will break easier. My assumption has always been that thus is due to the higher apuis resulting in less support against the rotational torque.

Also may be true that many makers set necks with  the button end of the neck a bit tighter than higher up on the theory that if the button area can't move the rest of it can't move.

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9 hours ago, David Burgess said:

How so? I've played, and spent some time examining that fiddle, and that wasn't my impression at all.

;)

We discussed this before and it turned into a shitstorm. I shouldn't have mentioned it.

So, to move on ...

Although Jerry insists on casting restoration/conservation as an issue he's in charge of and that I'm not involved in, I have to take decisions about these issues all the time, and I'm working with some very fine restorers. We discuss ideal neck angle/set all the time, I think it's a very good subject for discussion, and probably the single most interesting conundrum in relation to conservation.

Maybe I am in a minority, but my sense coming out of the end of this thread is that there is in fact an ideal point of equilibrium for a set-up, and that for a given ideal bridge height and string angle, that point of equilibrium is governed more by the nut position than the overstand, though of course both are in play. I think it might be possible to pin that point of equilibrium down in relation to a "centre line" of the body of the instrument ("centre line" as in Japanese timber framing technique). Move the nut away from this ideal position (either up or down) and the structure undergoes more stress.

So then the question is whether a perceived tonal benefit should be put before the structural weakening. I agree that most times the structure can take it and is strong enough even in the long term. But a lot of times it isn't.

In this thread it has been demonstrated that raising the nut and the overstand raises the torque on the top block. In a heavily built violin probably that added torque isn't enough to drag anything out of position, even over 200 years. But equally we have all seen violins with a deformation of the top plate that tells us the top block has tilted forward. 

I would love to go forward with this and to speculate about whether the back can really stretch or flatten, and about how the post and the bridge split or mitigate these forces ....

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I allways have the nut position as the main reference, when aiming for ~158 deg over the bridge all the other parameters are floating depending on how the violin body is constructed.

 

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53 minutes ago, martin swan said:

;)

We discussed this before and it turned into a shitstorm. I shouldn't have mentioned it.

So, to move on ...

Although Jerry insists on casting restoration/conservation as an issue he's in charge of and that I'm not involved in, I have to take decisions about these issues all the time, and I'm working with some very fine restorers. We discuss ideal neck angle/set all the time, I think it's a very good subject for discussion, and probably the single most interesting conundrum in relation to conservation.

Maybe I am in a minority, but my sense coming out of the end of this thread is that there is in fact an ideal point of equilibrium for a set-up, and that for a given ideal bridge height and string angle, that point of equilibrium is governed more by the nut position than the overstand, though of course both are in play. I think it might be possible to pin that point of equilibrium down in relation to a "centre line" of the body of the instrument ("centre line" as in Japanese timber framing technique). Move the nut away from this ideal position (either up or down) and the structure undergoes more stress.

So then the question is whether a perceived tonal benefit should be put before the structural weakening. I agree that most times the structure can take it and is strong enough even in the long term. But a lot of times it isn't.

In this thread it has been demonstrated that raising the nut and the overstand raises the torque on the top block. In a heavily built violin probably that added torque isn't enough to drag anything out of position, even over 200 years. But equally we have all seen violins with a deformation of the top plate that tells us the top block has tilted forward. 

I would love to go forward with this and to speculate about whether the back can really stretch or flatten, and about how the post and the bridge split or mitigate these forces ....

I'm up to page 7 and you are making a lot of sense Martin, I agree with all of your points I've read so far. Another poster? Not so much.

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3 hours ago, martin swan said:

;)

We discussed this before and it turned into a shitstorm. I shouldn't have mentioned it.

So, to move on ...

Although Jerry insists on casting restoration/conservation as an issue he's in charge of and that I'm not involved in, I have to take decisions about these issues all the time, and I'm working with some very fine restorers. We discuss ideal neck angle/set all the time, I think it's a very good subject for discussion, and probably the single most interesting conundrum in relation to conservation.

Maybe I am in a minority, but my sense coming out of the end of this thread is that there is in fact an ideal point of equilibrium for a set-up, and that for a given ideal bridge height and string angle, that point of equilibrium is governed more by the nut position than the overstand, though of course both are in play. I think it might be possible to pin that point of equilibrium down in relation to a "centre line" of the body of the instrument ("centre line" as in Japanese timber framing technique). Move the nut away from this ideal position (either up or down) and the structure undergoes more stress.

So then the question is whether a perceived tonal benefit should be put before the structural weakening. I agree that most times the structure can take it and is strong enough even in the long term. But a lot of times it isn't.

In this thread it has been demonstrated that raising the nut and the overstand raises the torque on the top block. In a heavily built violin probably that added torque isn't enough to drag anything out of position, even over 200 years. But equally we have all seen violins with a deformation of the top plate that tells us the top block has tilted forward. 

I would love to go forward with this and to speculate about whether the back can really stretch or flatten, and about how the post and the bridge split or mitigate these forces ....

For the love of god man, nobody is talking about doing anything dangerous to any instruments, or any “structural weakening”! You cannot raise the nut without raising the projection.  The nut is part of the lever arm......  We are not talking about doing anything different than what has been done forever, only about why the positive effects take place.....The “point of equilibrium”  you mention is what we have been talking about all along.  If you consider these things with restorers all the time, it makes sense to understand what  is happening instead of insisting someone is doing something dangerous without grasping the principles involved.

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9 hours ago, Don Noon said:

As long as this thread's meandering all over the place,

Where and how do cello necks break?

- Do the heels split, and the neck immediately falls out?

-Do the heels split, but only drop in projection slightly yet remain glued in the mortise?

-Do the heels split, but not much change in projection right away?

(I'm interested in those that break with no immediate trauma as the cause)

One thing that had to be considered whent talking about the forces in the neck/block/back position, if you are perceiving this construction as some kind of lever model (for me it is fixed construction under the load, not ideally rigid only becouse of the material fisical properties and construction shapes),  is the construction of the mortice. It`s vertical angle in particulary. There is a diference between the back mortice wall being perpendicular to the rib/block structure or being slanted toward the inside of the block. The second, leaning inwards one, where the contact/gluing area is almost perpendicular to the string pulling force direction will withstand the load with greater stability and resistence than on the "vertical" one. Also the compression efect on the edge of the top (and along the block) bill be lesser that way. But in the same time, in this second scenario there will be more "lever" force loaded on the back/block contact area. With slanted mortice back wall, the gluing area (it`s height line) is taller than ribs+top edge which would be the case on perpendiculary executed mortice. Since the angle between the button and mortice is bellow 90° the neck heal bottom is acting as a wedge, or as a kind of lever which is trying to push the button and back/block gluing area down (to break or unglue the back/block contact) when pulling force is acting on the pegs/neck. But since the top of the neck (a torque point) is not a hinge, neck has also a chance to release itself from the mortice construction just sliding verticaly in the line of the mortice.

So If the joint at the button and neck root glue joints are not the best ones, that described wedge/lever up lifting force at the heal / button could  theoreticaly produce a clean (non trauma) break. 

But now, imagine that the whole instrument is solid monostructure, let`s say printed on 3d printer which is able to mimic diferent densityes of the violin parts too. No joint, just rigid (not idealy) structure. Do the string tension forces react with the structure in the same way as on, made of glued parts, "normal violin?

 

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21 minutes ago, Jerry Pasewicz said:

For the love of god man, nobody is talking about doing anything dangerous to any instruments...read please.   YOU CAN NOT RAISE THE NUT AND KEEP THE PROJECTION WITHOUT RAISING THE OVERSTAND!!!!!  The nut is part of the lever arm......some of the smartest people I have ever known have explained this, and yet.....  We are not talking about doing anything different than what has been done forever, only about why the positive effects take place.....The “point of equilibrium”  you mention is what we have been talking about all along, (which btw, is why I brought it up on the first page).  if you consider these things with restorers all the time, why not understand what the hell is happening instead of insisting someone is doing something dangerous without grasping the principles involved?

Jerry, no need to shout. I'm sure Martin understands neck projection.

I'm up to page 11 now, but speed reading. Martin's diagram just made things more complictated because it was too hastily drawn.

We have lot of variable measurements at work here, there is also fingerboard thickness, which Blank Face mentioned. There is also fingerboard bow introduced by the luthier and figerboard/neck bow introduced by string tension. As well as nut height and saddle height and neck angle/planing angle affecting the nut height relative to the whole set up.

It seems to me that 6 mm is the standard modern overstand as both a general practice and an average measurement since the modern neck was introduced. But surely that doesn't mean that the overstand has to be 6mm? If the other variables can be altered?

 

 

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13 minutes ago, sospiri said:

Jerry, no need to shout. I'm sure Martin understands neck projection.

I'm up to page 11 now, but speed reading. Martin's diagram just made things more complictated because it was too hastily drawn.

We have lot of variable measurements at work here, there is also fingerboard thickness, which Blank Face mentioned. There is also fingerboard bow introduced by the luthier and figerboard/neck bow introduced by string tension. As well as nut height and saddle height.

It seems to me that 6 mm is the standard modern overstand as both a general practice and an average measurement since the modern neck was introduced. But surely that doesn't mean that the overstand has to be 6mm? If the other variables can be altered?

 

 

You are right, I shouldn’t shout.

Of course, you are correct.  The the lever arm is the point at which the string is located when it crosses the joint.  As was explained before, the appui is the representation, meaning, if you wish to take a neck, and raise the point on that lever arm (the string) crosses the joint, and have all the other relevant measurements stay the same, you raise the appui.  This assumes that all measurements are to spec.

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10 hours ago, Don Noon said:

As long as this thread's meandering all over the place,

Where and how do cello necks break?

- Do the heels split, and the neck immediately falls out?

-Do the heels split, but only drop in projection slightly yet remain glued in the mortise?

-Do the heels split, but not much change in projection right away?

(I'm interested in those that break with no immediate trauma as the cause)

Don, I don't think I've run across one which broke without trauma, except when a neck with very high moisture content was glued in, and the block didn't allow it to shrink as it dried and contracted.

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5 minutes ago, Jerry Pasewicz said:

Of course, you are correct.  The the lever arm is the point at which the string is when it crosses the joint.  As was explained before, the appui is the representation, meaning, if you wish to take a neck, and raise the point on that lever arm (the string) crosses the joint, and have all the other relevant measurements stay the same, you raise the appui.  

So the appui is the height of the string above the block (or the purfling?) and includes also

2, The overstand

3, The fingerboard thickness

3, The fingerboard bow that the luthier included

4, The natural neck and fingeboard bow caused by string tension

5, The neck angle

6, The nut (slot)  height

Have I got that right?

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4 minutes ago, sospiri said:

So the appui is the height of the string above the block (or the purfling?) and includes also

2, The overstand

3, The fingerboard thickness

3, The fingerboard bow that the luthier included

4, The natural neck and fingeboard bow caused by string tension

5, The neck angle

6, The nut (slot)  height

Have I got that right?

Not really,  when we talk about raising the appui we do it while assuming none of the measurements change.  Similar to talking about changing the angle of the strings over the bridge assumes that the neck length is to spec, as well as string heights.

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1 minute ago, Jerry Pasewicz said:

Not really,  when we talk about raising the appui we do it while assuming none of the measurements change.  Similar to talking about changing the angle of the strings over the bridge assumes that the neck length is to spec, as well as string heights.

So can you please define appui more clearly? A diagram might help.

And maybe you misread my post? Does the appui include those measurements or not?

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15 minutes ago, sospiri said:

So can you please define appui more clearly? A diagram might help.

And maybe you misread my post? Does the appui include those measurements or not?

No, appui is overstand, different people measure from different places. It is the measurement from the edge of the top to the fingerboard as measured from the bass side. You may be confusing the “lever arm” concept from the drawing, which would more accurately stated would make those other measurments  irrelevant.

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1 minute ago, Jerry Pasewicz said:

No, appui is overstand, different people measure from different places. You may confusing the “lever arm” concept, which would more accurately stated would make those other measurments  irrelevant.

That makes no sense Jerry.It would really help if you explained things better and wrote clearly. For example what do you mean when you say "the appui is the representation"? Representation of what?

You are writing too quickly and making grammatical errors. I haven't confused anything, you have.

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1 minute ago, sospiri said:

That makes no sense Jerry.It would really help if you explained things better and wrote clearly. For example what do you mean when you say "the appui is the representation"? Representation of what?

You are writing too quickly and making grammatical errors. I haven't confused anything, you have.

Apologies, I am assuming you have read the thread.

Appui = overstand.

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"Appui" means "support", BTW. I'm grateful that my observations how this support can work to a violin top in regards of flutings, sides and considerations about the importance of bridge, bass bar and soundpost were supported by Don's valuable explanations.

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1 minute ago, Jerry Pasewicz said:

Apologies, I am assuming you have read the thread.

Appui = overstand.

Thanks. I've tried to read the thread, but I wished to add in those variables to show my belief that 6mm (from the purfling?) is a standard measurement not an absolute rule.

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