Official Luthiers Forum!

    I believe that this bridge will fail in the future. I'd be interested to see
amphoto of it in a year or two that could show rhe effects that the design
has had on the top around it. I agree with MichaelP that the torsional
forces that are typiclly present in more standard bridge designs of a lower
profile and wider footprint are effectively increased or even multiplied in
this design.

    The force that is applied to that front edge with a pin style bridge or a
pinless with the string originating in their courses at anchor points
behind the saddle are approaching that edge at more easily handled and
much lower angles than on this one.

    The height of the bridge, which was obviously arrived at partly to
accommodate the holes to direct the strings through it, creates a much
longer lever and adjusts the fulcum point (that front edge) farther from
the leverage point so the torque is increased radically.

    to directly address the question at hand, though, the typical bellying of
the top behind the bridge and the dropping in front of it toward the
soundhole will happen and may even be more drastic than on a typically
designed bridge/top configuration.....that's if the glue joint between the
top and the bridge holds up.....but I'd venture to say that this is where
failure will most likely occur first.

    We can only push the physical limits so far before we've obviously gone
too far for things to have any reasonable longevity or integrity. I've
repaired many Ovations and other brands that have the two Mother of
Pearl dots in the bridge behind the pins or anchors that cover the heads
of the bolts that are supposed to hold them down. They warp and pull up
in spite of the presence of the bolts and sometimes even tear the tops
apart as the glue joint fails and the nuts inside the guitar are pulled
through them by the tension of the strings.

    Bolting or screwing down a bridge is never the answer to lifting or
preventing it. A good fit that is achieved by no other means than doing it
right while paying attention and taking care is the only thing that will
really keep a bridge in place for a long time. That and using the right
glue.

Regards,
Kevin Gallagher/Omega Guitars

[QUOTE=Hesh1956] Pat how come something that looks like a burial mound has a Van Linge/Hesh flavor to it....... (note the emoticon...)

It reminds me of a snickers bar....... [/QUOTE]

Not to offend here Hesh, my friend, but it does have a certain "stealth" characteristic that I see in yours and Scott's. And let me say the resemblance stops there!

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now known around here as Pat Foster
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http://www.patfosterguitars.com

Just realized who this builder is: Boaz Elkayam, studied under Richard Schneider. He's appeared in American Lutherie several times. They did a story on him too.

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now known around here as Pat Foster
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http://www.patfosterguitars.com

I would have to agree that it looks quite dangerous. It makes sense to me that it would have extra force pulling on it to fail.I also agree with Kevin G. that bolting a bridge is never a good way to hold it down.

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Anderson Guitars
Clearwater,Fl. 33755

If it is a Boaz then I would guess that there has been reinforcement provided in some manner. Boaz don't built junk. It would be interesting to see under the top.

[QUOTE=Kevin Gallagher]     
    The height of the bridge, which was obviously arrived at partly to
accommodate the holes to direct the strings through it, creates a much
longer lever and adjusts the fulcum point (that front edge) farther from
the leverage point so the torque is increased radically. [/QUOTE]

Aside from the torque issue, I also see a problem arising from the bridge height dramatically limiting the height of saddle which could be used without either compromising the playability or the tonal response of the guitar.

As is, the break angle may LOOK extreme, but to my mind, a portion of the force generated by the string tension would be absorbed at the back of this bridge well before the take off point to the saddle and therefore, I think this design has the potential to rob a percentage of that force which would normally be applied down onto the saddle to drive the diaphragm.

But I must add that I too could be completely wrong.

Cheers

Kim

I think I disagree with the majority of you on this one. On any pinless
design, like a Lowden for example, the majority of the force is acting to
pull the back of the bridge (or anchoring point) toward the headstock.
There is no doubt that a normal pinned bridge has less shearing force
acting on the back of the bridge because the strings anchor on the bridge
plate. However, a pinless design is more than adequate for a steel string
- and as long as the glue joint is very well-made, the bridge will hold on
for a very, very long time - just ask Dermot Mcilroy or George Lowden.

Let's get one thing straight tho' - and that is there is no more net force
acting on this guy's bridge than any other pinless design. What you have
to do is evaluate the pulling force and separate them into their
appropriate vectors.

On this particular bridge, the anchoring point for the strings is still at the
back of the bridge. The point where the string bends sharply is for all
purposes, the ball end of the strings.

The only thing that worries me about this design is that the pulling force
has a greater upward component than most designs. This means there is
more torque on the soundboard. However, I think if you crunch the
numbers, you will find that the difference is not that substantial.

However, I use a pinless bridge and I purposely aim to have a lower string
break angle and thus decrease torque as compared to a pinned bridge.

If I were to use a similiar design, I would definitely give the bridge a
bigger front-to-back footprint. But in my opinion, the small footprint
and the greater string angle (i.e. more torque) are the only differences
between that and a normal pinless bridge.

At least, that is my take on the situation. But pay no attention to me

...cause I'm a dufus.


--
Simon

SimonF39042.7527546296

[QUOTE=MichaelP] If it is a Boaz then I would guess that there has been reinforcement provided in some manner. Boaz don't built junk. It would be interesting to see under the top.[/QUOTE]

Other photos of the guitar on the link that Joe put up show there's something under the top between the soundhole and bridge that we're (OLFers) not used to seeing. And from what little I've seen of Boaz's other instruments, that seems highly likely.

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now known around here as Pat Foster
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http://www.patfosterguitars.com

I would think most of the string load is at the rear
of the bridge. What I don't like is the sharp bend
that the strings have as they come out of the rear of
the bridge. The strings would kink and break easy.

Tom

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http://www.moriciguitar.com

I am kinda supprised how many felt so strongly that this was a disaster waiting to happen. When I look at how the strings wrap around the bridge(taking such a sharp turn). I thought it would pretty much act much like a regular pinned bridge. In fact if you stuck a little pin in each of those holes it would probably not seem like a wrap around at all(at the angle they are at they might as well be pinned). As far as the weight. It looked tall and skinny in the first pic, but seems pretty normal in other pics(I wouldn't have thought it would be heavier than an Ebony bridge, and actually you reduce the need for pins which should drop some mass).
     I am getting ready to attach a wrap around bridge that I designed(very different from this design). I am curious to see if my thoughts are correct, but I really won't know until I give it a go. I will be sure to post pics, even if it fails miserably. If this topic is any hint of what I should expect. I suspect I am going to get a beating .

Peace,Richfryovanni39042.8971643519

Tom you are correct that is the moment that is inducing the torsion on the front edge I dont know if I was clear but the loading on this design , not counting any unseen reinforcement or tie pinning. wants to separate the back edge buy pulling upward and the forward pull of the strings past the saddle adds the rotation on the front edge. Some of the load ins in a slight downward direction at the saddle, but It would appear to me not as much as on a conventional bridge.

A couple have thought that the wrap counter acted the high lever effect. Actually the wrap is not much of an issue it is the upward and toward the peghead force as the stings exit the hole that i believe induce more that acceptable torsion on the front of the bridge and excessive shear on the rear.MichaelP39043.3983449074

     No matter how you wra the strngs through the bridge, there is no
reduct offered for the amount of tension, shear and torque force
pesented by the stings. The wrapping of these strings through the bridge
to almost 180 degrees opposition to the approach or exit course of the
strings is about double that presented by the break in the strings on a
pinned bridge.

   The simple leverage application here is explained by the height of the
bridge and saddle. All of the tension from the strings is applied to the
highest point and that is effectively the lever point. The fulcrum point is
obviously the very front edge of the bridge itself since that is where the
torque is focused. Even though failure would exhibit itself through the
lifting of the rear of the bridge, the force is applied to the front edge of
the bridge in a downward direction as rotation is the relief that torque
forces seek.

     This is leverage physics 101 and the shear forces applied to the rear
of the bridge are simply a result of the leverage system created by the
height and width of the bridge and saddle and the configuration of their
locations in relationship to one another.

     It's impossible to calculate all that would be necessary to determine if
failure may or may not occur since the top wood's fibers could vary
infinitely in their ability to retain integrity, the glue used could vary in its
strength of joint according to its chemistry, age and application and the
strings used by the player could present a wide variety of tension levels.

    I'm sure Boaz took into consideration all of this and the possibilities of
failure that could occur and took steps in preventing it from happening.
He builds a beautiful guitar. And in my limited experience with them,
since I've only played two, I've been very impressed with his tone and
response. The harmonic complexity of his instruments is what struck me
as most interesting, though.

    The bridge looks very nice and the design is graceful and fits the
overall aesthetic scheme of the guitar.

Regards,
Kevin Gallagher/Omega Guitars