The tapered versus traditional bracing ending

[Henning]

Hello, my question is about the shaping of braces. Does it have any significant importance how the ending of the braces are carried out?

This is, what I´d say, is the "common way" of doing it:

This is the way Martin did it in the mid forties (D28):

[Fathand]

They all work. Less wood in your braces tends to make them weaker but tend to make your guitar more responsive. Some attribute different tone qualities to the different brace shapes. Every piece of wood is different and the placement of your braces matters too. There is a ton of information to read about it online.

If you are building a first or 2nd guitar, it is probably best to follow the plans you have. The Grellier plans seem to be well respected if you are using those. I built my first guitar from the Grellier L-00 plans but I used pre-cut braces from aliexpress. They sound great and the guitar is holding together after 2 1/2 years.

[Henning]

I`m just making a rebuild of a vintage Levin, and making attempts in changing the bracing. Trying to tweak it and possibly squeeze out some more of it...hopefully...
It had two braces beneath where the bridge is placed. I´m interchanging it with just one.
The guitar is ladder braced with a floating bridge. I intend to set the single brace exactly under where the bridge is. (Now what effect that might have)
Regards

[Bruce Sexauer]

I have been inside a fair number of prewar Martin guitars, and the brace resolution in your second picture is news to me. Mostly I deal in OM/000 type guitars, but still . . .

The end treatment of the braces is not unlike what we call “scalloping”, in that removing material increases flexibility at the expense of structure. There are two ends on every brace, and not surprisingly, the structural requirements are not the same at both ends. Nor or they the same in the lower bout as the upper bout, or the back as opposed to the top. Assuming enough structure exists to avoid catastrophic failure, everything works, but to get the true magic that a guitar is capable of producing, there is a very narrow window of structure that is ideal. Being anywhere near that window in a factory situation requires a level and skill that is well above most factory employee’s pay grade, and invites call-back warranty issues that make the bean counters favor the kind of thing picture #2 demonstrates.

IMO, of course.

[Rudy4]

Originally Posted by Henning

Hello, my question is about the shaping of braces. Does it have any significant importance how the ending of the braces are carried out?

This is, what I´d say, is the "common way" of doing it:

This is the way Martin did it in the mid forties (D28):

Don't place too much stock in the Grellier plan as far as bracing details. The plan isn't particularly well drawn, and the "common way" is usually done with the top traverse brace, the X brace, and tone bar ends and sometimes lateral braces mortised into the body linings.

The Grellier plans are detailed enough to build a satisfactory instrument from, but it is a case of getting what you pay for with those particular plans.

I'm not saying that you won't have an acceptable instrument, but just be aware that slavishly following the drawing will not yield "conventional" or "Martin" bracing standards.

I'm not terribly familiar with Martin bracing, but I've never seen anything like your example other than from guitars that had owners who reached in to "round" the top of square bracing to "improve" on what Martin found to be an acceptable compromise between economics and structural integrity. These photos are often taken by shops where guitars come in with bellied tops, or worse. Martin used squared braces, scalloped braces, and scalloped and rounded braces as far as I know from the bracing I've seen in the past.

I HIGHLY recommend anyone who is new to building to follow a GOOD plan that's drawn from an authentic instrument. Spending good money on quality materials, putting in a LOT of sweat equity, and working from a free plan of the internet might be false economy.

[Henning]

Guys! *please* whenever answering a question in this forum, or wherever else, do check what the person who asked the question wants to know. Or simply what the question is about. Bruce, you really have the nerves to market yourself and your services!

[Rudy4]

Originally Posted by Henning

Guys! *please* whenever answering a question in this forum, or wherever else, do check what the person who asked the question wants to know. Or simply what the question is about. Bruce, you really have the nerves to market yourself and your services!

Here's your question:
"Does it have any significant importance how the ending of the braces are carried out?"

If you don't think that Martin didn't consider the method they chose to terminate and finish brace ends or their methods of brace shaping wasn't "significant" I don't know what to tell you.

If you cite incomplete or poor photographic representations of "standard" or "common" bracing and then ask questions based on those photos then you're going to get the responses you got.

Everyone here is attempting to send you in the right direction. What part of not addressing the original question did I not do?

Sorry about adding details "unrelated" to your question.

[Mark Hatcher]

Originally Posted by Henning

Guys! *please* whenever answering a question in this forum, or wherever else, do check what the person who asked the question wants to know. Or simply what the question is about. Bruce, you really have the nerves to market yourself and your services!

Henning, in the world of guitars the best answers are usually much larger than seemingly small questions. You’ll need to get used to that if your goal is to be successfull.

[Bruce Sexauer]

I read the OP’s question and my response several times this morning, and and I do think my words are spot on and and thought provoking in an entirely helpful way . . . However, I did not notice at the time that the OP is probably not a native English speaker, so a will rephrase my answer into its simple but less useful essence: Yes.

[Skarsaune]

Originally Posted by Bruce Sexauer

I read the OP’s question and my response several times this morning, and and I do think my words are spot on and and thought provoking in an entirely helpful way . . . .

They were, as always.
Thanks for your contributions to this forum.

[runamuck]

Originally Posted by Henning

Bruce, you really have the nerves to market yourself and your services!

I don't understand this.

Bruce mentioned that he's been inside a number of Martins that, from my perspective, simply establishes the fact that he's been around the block a number of times. That is helpful and lends credibility to his opinion for those who have no idea about his work over the decades. If you've ever played one of his guitars....

The remaining part of his post is simply informative and factual.

EDIT - Maybe you were just kidding! I hope so.

[Fathand]

Originally Posted by runamuck

I don't understand this.

Bruce mentioned that he's been inside a number of Martins that, from my perspective, simply establishes the fact that he's been around the block a number of times. That is helpful and lends credibility to his opinion for those who have no idea about his work over the decades. If you've ever played one of his guitars....

The remaining part of his post is simply informative and factual.

EDIT - Maybe you were just kidding! I hope so.

Thanks for this post, I agree and you said it better than I could have. I appreciate a lot of information I have gleaned from Bruce's posts over the years and have never seen one that felt like "marketing".

[Henning]

Originally Posted by Rudy4

Here's your question:
"If you don't think that Martin didn't consider the method they chose to terminate and finish brace ends or their methods of brace shaping wasn't "significant" I don't know what to tell you.

If you cite incomplete or poor photographic representations of "standard" or "common" bracing and then ask questions based on those photos then you're going to get the responses you got.

Everyone here is attempting to send you in the right direction. What part of not addressing the original question did I not do?

Sorry about adding details "unrelated" to your question.

Dear Rudy4 and others too whom it might concern; I do beg your pardon for my previous post in this matter.

What I had wished for and hoped too, was an answer that would say something like: "if you do like alternative 1. this will happen.... But if you do like alternative 2. the result will instead be....

But I realize it might not be possible to give such an answer, due to the facts that there are so many parameters involved that are unknown.
Sorry

[Rudy4]

Originally Posted by Henning

Dear Rudy4 and others too whom it might concern; I do beg your pardon for my previous post in this matter.

What I had wished for and hoped too, was an answer that would say something like: "if you do like alternative 1. this will happen.... But if you do like alternative 2. the result will instead be....

But I realize it might not be possible to give such an answer, due to the facts that there are so many parameters involved that are unknown.
Sorry

No problem. Unfortunately guitars tend to be much more complicated than that and often the only way those relationships can truly be ascertained is by direct experimentation. That is indeed how most of the modern steel string guitar design was evolved, so that's why it's not possible to provide those types of answers to your questions.

In any case, good luck with your project and do pop in and post your results here. Levin instruments have a long history and direct ties to instruments that were later manufactured here in the U.S.

[Alan Carruth]

As has been said in this thread; there are plenty of simple questions you can ask about guitars, but very few simple answers.

One thing you have to consider when shaping the brace ends and how they intersect with the side is what the mechanical load is on the brace. Because of bridge torque any brace end between the bridge and the upper edge will be under a down load. The neck, of course, also produces it's own torque.

Brace stiffness goes as the cube of the height. If there's a down load near the edge of the top the brace will not be able to flex with the top at the end if the brace is much more than, say, 1/3 as tall as the thickness of the plate. This produces a peeling force in the glue line holding the brace to the top. To prevent the brace coming up the end has to be let into a notch in the liner, or otherwise supported by some sort of bracket that won't allow the brace to come loose from the top.

Some makers feel that it is not necessary to inlet top brace ends that are behind the bridge, since the static force there is pulling the brace upward into the plate. This ignores the possibility of a blow to the top that could produce the down load. Better safe than sorry IMO, but that's just me. Any brace that is not inlet into the liners or supported should taper out, over a long distance to distribute the bend, to much less height then the thickness of the plate.

It is unclear how tall the brace end needs to be from a structural perspective. If it's too low a blow on the top or back could split the brace near the end. The profile of the taper matters here, most likely. It's also especially important to avoid notches or other 'stress risers' at the ends. I tend to leave the ends of the upper transverse brace and the upper ends of the 'X' tall, and decrease the height of the ends from there back to the tail. Usually I make back brace ends uniform in height.

Gibson used to use a sanding machine to take the brace ends down in a uniform radius to nothing at the end. They seem, in many cases, to have simply counted on the brace end to crush the liner when the back was glued on, avoiding the need to cut notches. Since the liner and the brace were often both spruce the liner was frequently hard enough to do the crushing at the expense of the brace, which was effectively cut off along the inner edge of the liner. This left the brace end tall enough at that point to produce a peeling force in the glue line, and they'd peel up. I used to get repair customers with Gibsons that had the neck folding up, and the UTB missing. I'd ask about that and they'd remember throwing out a stick that was rattling around inside the guitar. As Bismark said:
'Any fool can learn from their own mistakes; a wise man learns from the mistakes of others"


The height profile of the brace makes a difference in how much it stiffens various areas of the top, and alters the timbre. There is endless discussion about this. As a very broad generalization, bracing that is low in the center of the top ('scalloped profile') tends to favor bass and 'punch', while bracing that is higher in the center and tapers down to the edges favors 'treble balance' and sustain. There are many opinions beyond that. If you ask 25 luthiers what the 'best' way is, you'll get at least 50 answers...