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I have been reading the information in the thread about "torque" and rotational forces , I am not a Engineer . However I do have background in Arch. Drafting and design . So im not a total layman . My question is " why do most builders go with a saddle and bridge mounted on the top verses a tail piece mounted to the tail block"
Ive noticed using a tail piece has been called hairbrained ?

Is there a better tone ? Less Stress on the guitar ? whats the main reason ?

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I'm not sure what the technical reasons are, but you do get a vastly different sound from a tailpiece setup than you do from a glued down bridge. The tailpiece ones have a, to me, brighter tone and less of a bass sound.

Others here can explain it way better than I.

-Matthew

At root, the issue is that you need to keep the strings in contact with the top of the saddle at all times. Usually this is done through 'downbearing': the string 'breaks' down over the saddle at some angle that's greater than any angle the string is likely to make upward. A little more than five degrees is generally enough, but usually the break angle is more like 20-40 degrees.

If you draw a side elevation of the top, with a saddle in the right place at the right height above the top, and extend the line of the strings back from the saddle top with the correct break angle, you'll see that they intersect the top a little way behind the bridge, and long before you get to the edge of the top. You can't get enough break angle on a flat top guitar by tying the strings off at the tailblock.

Since this is what a free floating tailpiece does that won't work on most flat tops either. They do make tailpieces that push down on the strings: you see them on banjos, for example, but most guitars don't use that sort of thing. You can make a 'hook' tailpiece, that pivots somewhere down on the side, but that's got it's own mechanical problems.

You could angle the neck back, and put on a tall bridge. This produces a lot of down force on the top and would cave a flat top in fairly quickly unless it was braced heavily. Arching the top helps a lot, and that's the solution Orville Gibson adapted from the violin. The arching stiffens the top considerably (which is the point, after all), and has other effects on the acoustics, that tend to give a more 'treble balanced' and 'forward' sound. This is made even more pronounced by the use of 'F' holes rather than a round or elliptical one.

You can also 'crank' the top: bend it down out of the way behind the bridge. This was used in old times on the 'chittarra battante', and is the setup on Neapolitan mandolins. The crease, and the reinforcing brace under it, pretty well splits the top into two parts, and tends to kill the bass.

You can also make slots in the bridge top to catch the strings, and then you don't need a downward break. This is what resos do. There's a 'new' design that achieves that by fanning the strings out behind the bridge and attaching them to the edge of the top. Or you could look at a piano bridge.

Any system that takes the attachment of the strings away from the bridge eliminates the twice-per-cycle tension change signal as a driving force. This is _not_ a major contributor to the power of the guitar, but it does effect the timbre to some degree. It's not the _main_ reason, as far as I can tell, for the characteristic sound of tailpiece plucked instruments; that seems to have more to do with the things, like arching or cranking the top, that you have to do to get the strength and the downbearing angle. It's possible, but tricky, to get very nearly a 'flatop' sound from an archtop, or vice versa.

Torque on the bridge is what kills guitars, so it's helpful to try to get rid of it. However, from what I've heard, it doesn't seem to do much good to then reduce the bracing and lighten up the top. The ones I've heard like that have not impressed me with their sound, although I'm told there are good guitars made that way. It seems to me as though the designs that have been worked out over the years have arrived at the 'right' combination of top mass and stiffness to both sound 'good' (whatever that means) and withstand the bridge torque for 'long enough'. It's a surprisingly robust design in many respects.

thanks for the insight

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The Taking Of Offense Is the Life Course Of The Stupid One !
Wanna Leave a Better Planet for our Kids? How about Working on BETTER KIDS for our Planet !
Forgiveness is the ability to accept an apology that you will probably NEVER GET
The truth will set you free , But FIRST, it will probably Piss you Off !
Creativity is allowing yourself to make Mistakes, Art is knowing which ones to Keep !
The Saddest thing anyone can do , is push a Loyal Person to the point that they Dont Care Anymore
Never met a STRONG person who had an EASY past !
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I build Selmer/Maccaferri guitars. They have a floating bridge like an archtop, but the tops are flat (flat/thin top mated to arched bracing). Since I think the sound of a Selmer is nifty and others do too, the overall architecture has some things going for it... If it didn't, then Selmers and all other traditional archtops would all have glued on fitted bridges. Just my $.02

First of all, absorb what Alan said. Next, to answer your question directly, I believe most builders attach their tailpieces with a cello gut or with a hinged mount off the tail pin position because that is traditional.
Archtops are more or less derived in concept from violin and viola-style instruments, so it is natural that very many of their tailpieces would be attached by some means at the tail pin position. Having said that, some builders DO sink a mounting pin down through the top near the tail edge of the guitar, and mount their tailpieces to that pin. I have seen pictures of beautiful instruments made that way. How these instruments compare tonally to a guitar with a cello gut tailpiece I couldn't say from personal experience.
However, they can look quite beautiful and functional, and I see no reason why you shouldn't experiment with this concept if it appeals to you. Just realize that it is not the norm in the marketplace. If it is a guitar for you own use, that won't matter. If you intend to try to sell it, you should probably stick closer to the market norm.

i have some more question on this topic
why use a pinned bridge over a pinless bridge (like on an Ovation)
Is there a better tone ? Less Stress on the guitar ? is the builder being cheep? whats the main reason ?
Also, ive heard that you get a lot better tone and volume from strings that have the ball ends pinned inside the box. anyone have any thoughts on that?

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Just re-read my earlier response, and I realize it might have been confusing. To clarify, I was talking about archtop and cranked top instruments. You were probably asking about flat top instruments. Like I said, read and absorb what Alan said. You could still use a tailpiece if it appeals to you--employing any of the methods that Alan detailed. As to your follow up question about pinned versus pinless bridges, I'll be interested in the responses, too.

I'm fairly new at this so I won't be able to give you a complete answer. I will address one difference between a Martin style pinned bridge and an Ovation bridge where the strings terminate in the bridge without going through the soundboard.

On an Ovation style bridge, all the force of the tension in the strings (roughly 180lb I've read) is pulling on the bridge. The only thing attaching the bridge to the top is the glue underneath the bridge so there is a considerable stress on this glue line. I've read it's not uncommon for these bridges to pull loose (but have never experienced this on the Ovation I own).

On a Martin style, pinned bridge, the strings run through the bridge, through the sounboard, and through the bridge plate where they terminate. The tension of the strings pulls up on the bridge plate and pushes down on the saddle. So somewhere between the string termination point and the saddle, the bridge, top, and bridge plate are being compressed together. The front of the bridge is being pushed down into the top while the rear of the bridge is trying to lift off the top. Overall, this seems to reduce the stress in the glue line under the bridge considerably over the Ovation style bridge (my opinion) so less chance of the glue failing and the bridge pulling loose.

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We need an expert on Django type guitars to chime in (Colin?). They are basically flattops with a tailpiece. Acoustically, they are a LOT different, at least to my ears.

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Dave
Milton, ON

pzwinakis wrote:
"I build Selmer/Maccaferri guitars. They have a floating bridge like an archtop, but the tops are flat (flat/thin top mated to arched bracing)."

I have no direct experience with SelMac style guitars, but I do have Mike Collins' book. On page 81 he says:
"The soundboards of the original steel strung Selmer-Maccafferri instruments differed greatly from all preceding guitar tops by incorporating a unique feature, the 'pliage'. The pliage is a bend in the top just behind the bridge."
He goes on to talk about how this was copied from the Neapolitan mandolin.

Do you build the same way? If not, how do you keep the strings in contact with the bridge? As I said, break angle is only one way, even if it is the most common method used on guitars.

The pliage does not have any effect on the geometry of the tailpiece/breakover angle as the sides are not taken down like they are on a Neapolitan mandolin behind the bridge... The total top arching is about 10mm and the bridge is about 17mm tall, so the breakover angle is probably like a flatter archtop.. It works though... Not for folksy strumming, but it works...

pzwinakis wrote:
"The total top arching is about 10mm and the bridge is about 17mm tall, so the breakover angle is probably like a flatter archtop.."

That's a pretty high dome, and a tall bridge!

As nearly as I can figure out, you need about 6 degrees of break angle. I'd have to draw it out to be sure, but based on your nyumbers, I think you're probably getting that.

Hi, I've been tempted to make my first post by this thread. The pliage (crease) angle on the Maccaferris, at least according to the Patrick Alexander/Francois Charle drawing, is 6 degrees. If you cut the guitar in half longitudinally, viewed from the side, the top as far as the bridge, is a straight line continuation of the neck without finger board. The fingerboard, which is glued to the top, is 7mm thick. Immediately behind the bridge, the top is bent down, in a straight line, 6 degrees. The bridge is 18mm high. Drawing a straight line from top of the zero fret to the top of the bridge, and then to the string attachment point on the tailpiece, gives a break angle of close to 12 degrees.

I'm confused-If you guys saying a tailpiece on a flattop dosen't work,I beg to differ.
Stella, Gibson and many other companies and hand makers are using tailpieces and they seem to sound pretty good to me-whatever the break angle is.

I'm not saying that a tailpiece can't work on a flat top, I'm just pointing out that it probably won't work by giving a good solid break angle over the top of a smooth saddle. If, for example, you notch the saddle so that the strings are pinched then you may not need any break angle. That's how resos work: you really can't put much down force on that light aluminum cone. It's also how pianos work, and I did mention that in my first post, although I was not too specific.

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Dennis, did you build that one? I have wanted to try out a design like that. Did you do anything special with the bracing? How does it sound? Thanks!

Ditto on the questions! That is a cool design idea!

Thanks sondre and mateo,

So the thread does not get hijacked (I was just showing one way to use both a tailpiece and a big break angle), I'll PM you a link about that guitar. There is probably more than one person here tired of me talking about it anyway.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

hijack away my friend , its a beautifull piece of work , feel free on my part to talk about it. as a matter of fact , i want to know how the stress from the strings at that break angle doesnt tear out the wood ? Or am i thinking about it backwards ?

How would ebony hold up in that instance ?

_________________
The Shallower the depth of the stream , The Louder the Babble !
The Taking Of Offense Is the Life Course Of The Stupid One !
Wanna Leave a Better Planet for our Kids? How about Working on BETTER KIDS for our Planet !
Forgiveness is the ability to accept an apology that you will probably NEVER GET
The truth will set you free , But FIRST, it will probably Piss you Off !
Creativity is allowing yourself to make Mistakes, Art is knowing which ones to Keep !
The Saddest thing anyone can do , is push a Loyal Person to the point that they Dont Care Anymore
Never met a STRONG person who had an EASY past !
http://wiksnwudwerks.blogspot.com/
http://www.facebook.com/groups/GatewayA ... rAssembly/

Thanks, Dennis! That's one magnificent guitar! Can't believe it's your first...

No James, you're not thinking about it backwards. I was worried that the strings would rip off that trailing piece of wood too (but it has lasted 3-1/2 years so far.) I hedged my bet by using Katalox for the bridge material, as (I believe) it is more difficult to split than any of the Rosewoods or Ebonies. I also exited the strings low, which kept (relatively) a lot of wood above the strings.

I just showed it because it is one way to have both a tailpiece and a typical break angle over the saddle. I think that when the discussion comes up among luthiers about "why not use a tailpiece on a flattop guitar?", that the first thing almost all luthiers think of is a hybrid guitar that is built like a steelstring flattop, but then has some variant of an archtop bridge planted on top. The marketed examples of that hybrid approach were met with less than stellar (well, poor) reviews from most players, and folks like Al Carruth can explain the physics of why an archtop bridge does not yield the same "punch" or "bite" to the overall sound as a steelstring with a typical steelstring bridge. My hunch was that the break angle over the saddle was the key to that "punch" or "bite", and I proved it to myself in a single experiment.

That bridge has almost no shear force from the strings, but probably has about the typical torque of a typical pinned or pinless "stop" bridge. My next experiments will get much closer to the Steinberger/Grimes "stress-free" bridge concept.

Now that I went searching again for the Steinberger/Grimes patent to link it here, I found this article:(Neutral Tension Bridge), showing yet another luthier that (evidently) reinvented the concepts Steinberger and Grimes patented in 1996. (And, from what I know of the USPTO, this luthier, Rick Toon, will probably be granted yet another patent, regardless of the fact that it is clearly a rehash of the Steinberger/Grimes patent.) By the way, my "Angelina" guitar using these concepts was built "in public" (on a public forum) in 2004 which is then "prior art" and (after a brief public discussion about the pros and cons of patenting my ideas - never having seen Steinberger/Grimes patent) my concepts were noted as being offered into the public domain. I mention all of this because the last thing I want is a further impediment to getting luthiers to experiment with the concepts of a different way of engineering guitars that employs three key elements:
1.) suspended bracing (or rims reinforced in such a way that the guitar rims alone can withstand the 160+ pounds of string force)
2.) a "tunnel bridge" (or a variant) with the key element being a "proper" break angle over the saddle
3.) a tailpiece, floating or integrated, to anchor the strings on the butt
the 4th element is your imagination: what is the best way to brace or not brace the guitar top, once the soundboard bracing no longer needs to be structural? How thick should the top be, or better yet, how much deflection? And I would ask all that join in the experiment to share the outcomes, good and bad and "different", so that we might all learn a variety of ways to add bracing that serves a sonic purpose (notice I didn't say, "makes a perfect sounding guitar" because I believe there may be many many voices that could all be "perfect" to some players and/or for specific songs or genres.)

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I was thinking of starting a new thread but I figure I'll post it here instead.

I do something similar in my banduras where the hole drilled in the bridge provides the break angle. You can see it in the picture. Now in my first build, the strings went all the way from the top of the bridge all the way to the level of the top creating a lot of down force on the top. Over my last couple of builds I've slowly been lifting the attachment point of the strings at the tail piece to eliminate the down force because my tops end up flattening (or in some cases even going concave) due to the downforce. You can see the "tailpiece lift" in the attached pic.

And you know what, my sound has been improving with each instrument and my tops have been deforming less and less. I'm not ready to put a causal relationship between the lack of downforce and the good tone but I at least believe it's not having a negative effect at this point.

In my next couple of builds I'm going to make the lift the same height as the saddle to get rid of as much downforce as possible (there will still be some due to a chromatic row of strings that will always have a significant break angle) and see what happens.

I have a thought and related question regarding how to get a good sound like this and why this wouldn't work on an archtop or violin type of instrument without modifying the design significantly.

In an archtop instrument, specifically of the violin family, you need a lot of downforce and break angle on the floating bridge to keep the strings firmly "connected" to the bridge while playing. A violin bow introduces a lot of energy into the string and without enough break angle, the string may "bounce" off of the "saddle". To deal with this effect, I glue my bridges to the top (as do the other zero torque/tension designs). This mechanical connection between the bridge and top in conjunction with the break angle provided by the holes in the bridge means that a vibrating string may displace the top "upward" without bouncing off the saddle.

The question is: how does the down force on the bridge affect the tone? It stands to reason that the downforce will raise the tap tones of the top the same way stretching a string or bending a saw raises their frequencies. One could also see that the top may vibrate differently when stressed than otherwise due to "preloading" of the top.

I've heard others say that increasing the downforce on an archtop type instrument will "increase the volume" but I just can't see how that could be so. The only thing I could see is that increasing the downforce would increase the maximum amplitude at which the strings may vibrate without bouncing or buzzing. However, for a given amount of energy put into the string, either by plucking or bowing, I just can't see how it would be any louder with more downforce on the bridge.

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Dennis Leahy wrote:
"...folks like Al Carruth can explain the physics of why an archtop bridge does not yield the same "punch" or "bite" to the overall sound as a steelstring with a typical steelstring bridge."

I can tell you why an archtop _guitar_ usually has less 'punch' than a steel string flat top _guitar_, but I don't think it has a lot to do with the string forces on the bridge. It's a function of the stiffness that you have to build into an arched plate to keep the top from sinking over time under the down force of the break angle. The 'admittance' of an archtop is comparatively low, perticularly at low frequencies, so it takes a while for the energy of the fundamentals to get out of the string and into the top.

Tom Knatt, who was my guitar making teacher, built something very similar to your bridge back in the mid-70s. His idea was to switch back and forth from nylon to steel strings, so he used a regular tie bridge for the nylons, and a tailpiece to take up the tenson when using steel. It worked OK, but I'll note that he only made one.

"...what is the best way to brace or not brace the guitar top, once the soundboard bracing no longer needs to be structural? "

Let's say you've got 200 pounds of string tension (yeah, that's high, but it's just a number to use). Spruce is rated for useful loads in the range of 2000-3000 psi in direct tension or compression in aircraft use, so that implies a generous safety margin. If your top is .100" thick, and 15" wide, that gives it a cross sectional area of .15 square inches, which should be good for a load of at least 300 pounds in pure compression.

In order to take that load in pure compression the top would have to be dead flat, and remain so. The problem is that a thin plate like that is going to buckle under far less load than it can theoretically take in straight compression. When we took shoring classes in the Navy (bracing battle damaged sections of the hull) the rule of thumb we were given is that a member in compression could be no longer in free span than 12 times it's smallest dimension: a 2x4 that was really 2" thick could only be 24" long. Even without the torque load the structural limit on the top is it's buckling strength. e don't use bracing to take up the compression load, but to slow down buckling.

From what I've seen and heard over the years, reducing the bracing very much from 'normal' sizes doesn't improve the sound much, if it doesn't actually hurt it. At any rate, the bracing is only 1/3 or so of the total weight of the top without the bridge, so cutting down on the brace weight isn't that much of a help. If you really want to make a difference, use the same bracing and reduce the thickness of the top by about half. That's the same as eliminating the bracing altogehter in terms of weight, and retains most of the stiffness.

As for patents: the patent office stopped examining claims years ago for anything but obvious weirdness: they won't accept an aplication for a perpetual motion machine, for example. The problem was that the technology had gotten so complex, and the number of applications so high, that it was impossible for the government to keep up, either in expertise or in numbers of examiners. Instead, they simply started issuing patents to anybody, and relying on the courts to sort out things like priority. The fact that somebody maintains a patent an old idea simply means that nobody else has seen fit to mount, or wanted to spend the money on, a challange.