Official Luthiers Forum! :: View topic - Classical Fan Bracing Dimensions

All the folks in the world can tell you what dimensions they use. In the end the sound you are considering cross grain stiffness, top thickness, stiffness of your bracing, size and thickness of bridge patch and how you want all of this to play into your sound. I'd suggest picking a plan and running with it and thickness the braces to what feels right to you and what the top is telling you. I believe our eyes, ears and feel in the fingers tell us a lot if we listen with those senses. The fact that we can't always articulate a discrete metric as the outcome is akin to trying to press an n-dimensional world into a 1 dimensional representation. Unfortunately science relies largely on math as its lingua franca; there you have it. The premise that, if you can't represent it mathematically it must not be real (or right) is exactly what brings us to, "is it 6mm or 5mm" to get the "right" sound (whatever that is!)

I know on the Hauser I'm doing now, I went with the numbers that were provided as a starting point. In the end I tried to let my sense of what was going on guide the brace shape and overall stiffness of the top. I'm no expert, but I think the mechanistic reasoning around all this stuff can get taken too literally and off the beaten path of what actually matters.

Good luck. Please don't take my above comments as criticizing, but rather encouraging you to start somewhere and let your fingers and ears tell you where to take those braces. Please post photos and experiences as you undertake this classical. Mostly steel string folks here so it's great to see some classical stuff being posted!

Filippo

Author:	Pat Hawley [ Wed Mar 10, 2010 9:46 am ]
Post subject:	Classical Fan Bracing Dimensions
I'm getting started on a classical and have several books and plans (which perhaps may be my problem). Basically, I want to do the 7 fan brace Torres design. The thing is, that in my reference material I've got a very wide variation on dimensions for the fan bracing. For example, on the Torres plan, the braces are shown as being only 2.5 mm tall. In the plans that come with Robbie O'Brien's classical guitar building DVD, the braces are shown as being 6 mm tall. And I have other sizes in between. So I'm interested in opinion and/or advice on fan bracing size for a seven fan braced classical guitar. Thanks, Pat

Author:	Robbie O'Brien [ Wed Mar 10, 2010 10:30 am ]
Post subject:	Re: Classical Fan Bracing Dimensions
There are many dimensions available depending on the builder and what they are working with. For example, the Hauser plans you refer to use very small braces but you will notice that the top is a bit thicker and he used Euro spruce. In my classical DVD I am using cedar and my version of the Fleta 9 fan brace design. You will find measurements from around 3mm-5mm or even 6mm wide and 2.5mm - 7mm tall. That is a huge difference for a classical guitar. Find one that works for your purposes and go with it. On a classical guitar think of your bracing pattern as sound distributors and not structural. Good luck.

Author:	WaddyThomson [ Wed Mar 10, 2010 10:56 am ]
Post subject:	Re: Classical Fan Bracing Dimensions
Robbie is right. There are lots of different ways of doing it, and they all seem to work. The traditional Torres bracing is lijke 6 to 7 mm wide and 2.5 to 3.0 mm high. My braces are 3 mm wide and vary from 4 mm on the outside pair to 6.5 mm high, on the center 3 braces. I would go with whatever plan you are going for. Each will result in a slightly different sound, but the truth is that you are going to get your sound, what ever that turns out to be.

Author:	jfmckenna [ Wed Mar 10, 2010 11:48 am ]
Post subject:	Re: Classical Fan Bracing Dimensions
Yup either go short and wide or thin and tall. I've done both with good results. I still see the braces as structural on a classical guitar. I typically build the center three braces a bit stronger then the outer ones sometimes using Sitka for the center three and fading out to Cedar. It's all voodoo at this point to me but I like to try things and so far I have not built a bad sounding classical guitar and the 15 year old one that has been used and abused is still holding up, that one built by the Sloan method which was the short fat bracing scheme.

Author:	Colin S [ Wed Mar 10, 2010 12:03 pm ]
Post subject:	Re: Classical Fan Bracing Dimensions
On my Torres guitars, which are based on the Torres FE19, the fans are 3mm tall by 7mm wide. My Aram based on the FE13 are also the same. On this period Torres the braces had a gable end cross section. Colin

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Author:	Pat Hawley [ Wed Mar 10, 2010 1:06 pm ]
Post subject:	Re: Classical Fan Bracing Dimensions
Thanks for the feedback. I guess I'll go the short, wide route since my main reference plan is the Torres SE 114 and the top will be Englemann spruce. Cheers, Pat

Author:	senunkan [ Wed Mar 10, 2010 1:24 pm ]
Post subject:	Re: Classical Fan Bracing Dimensions
I use 7mm wide 3mm tall braces on my Englemann top. Also based on the Torres fan with kite apex at 14 fret but with open harmonic braces. One odd thing which I did was to make the cross section profile of the different The center 3 braces were having triangular profile whereas the out braces are having rounded. Originally all was having rounded profile, then I got my new chisel and I want to test how good the chisel is and use it to make the central 3 braces to become triangular in profile. Not sure why I did that though. Sen

Author:	David LaPlante [ Wed Mar 10, 2010 3:01 pm ]
Post subject:	Re: Classical Fan Bracing Dimensions
I'm usng 6.0 mm wide for the center 3, 5.5mm for #'s 2 and 4, and 5.0 mm for the outermost 1 and 7. I'm also using a treble bar and single "cut off" bar....but that's another topic. Shape varies depending on location. Some are taller and more "V" shaped, others are lower and dome shaped in cross section. As stated above, everyone has their own perception of this and it's really something you have to develop over time as you get a better sense of how things work and the proper degree of robustness needed on a classical guitar. Most of the commonly available plans will give good results (albeit different).

Author:	jlneng [ Wed Mar 10, 2010 7:02 pm ]
Post subject:	Re: Classical Fan Bracing Dimensions
One idea that might help guide you, get an inspection mirror or scope and find some vintage guitars to look inside. You might find some interesting surprises. If you know any owners who have vintage classicals, ask them if you can take a peek. I have examined numerous Rucks, Ramirez, 1942 Marcelo barbero, 1932 Doming Esteso and it really opened up my eyes. I build Flamencos but I am sure that you get the idea. Check out the top thickness too while you are at it. I have never had an owner say no. I think most take it as a complement. My 2 cents....My belief is that the bracing for a flamenco or classical is really dependent on how stiff and how thin the top is. If I have a stiffer top I make the braces alot shorter in height. If the top is not as stiff, I might make the braces taller in height. I use German Spruce for tops, and either spanish cypress or EIR for the B&S.

Author:	jfmckenna [ Thu Mar 11, 2010 9:14 pm ]
Post subject:	Re: Classical Fan Bracing Dimensions
Filippo Morelli wrote: All the folks in the world can tell you what dimensions they use. In the end the sound you are considering cross grain stiffness, top thickness, stiffness of your bracing, size and thickness of bridge patch and how you want all of this to play into your sound. I'd suggest picking a plan and running with it and thickness the braces to what feels right to you and what the top is telling you. I believe our eyes, ears and feel in the fingers tell us a lot if we listen with those senses. The fact that we can't always articulate a discrete metric as the outcome is akin to trying to press an n-dimensional world into a 1 dimensional representation. Unfortunately science relies largely on math as its lingua franca; there you have it. The premise that, if you can't represent it mathematically it must not be real (or right) is exactly what brings us to, "is it 6mm or 5mm" to get the "right" sound (whatever that is!) I know on the Hauser I'm doing now, I went with the numbers that were provided as a starting point. In the end I tried to let my sense of what was going on guide the brace shape and overall stiffness of the top. I'm no expert, but I think the mechanistic reasoning around all this stuff can get taken too literally and off the beaten path of what actually matters. Good luck. Please don't take my above comments as criticizing, but rather encouraging you to start somewhere and let your fingers and ears tell you where to take those braces. Please post photos and experiences as you undertake this classical. Mostly steel string folks here so it's great to see some classical stuff being posted! Filippo Well said! The blue print are basic dimensions and are great for beginning luthiers who just want to follow a recipe. Even my first guitar I started experimenting with my own thing which in hindsight was rather dumb but now I always try different things based on intuition and feel, hopefully coupled with experience. You know, it's hard from the time that you brace a top and feel it's flex till when it's finally strung up. Lots of variables in that equation to try and remember.

Author:	douglas ingram [ Fri Mar 12, 2010 3:58 pm ]
Post subject:	Re: Classical Fan Bracing Dimensions
There are a lot of variable, I'd suggest that you keep to the SE114 plan and really pay attention to the character of the top as you work it, brace it, and shape the braces. Only then will you have a reference. All the talk and numbers won't mean a thing till you have your own reference in your head and fingers. Good luck, it will be hard to go wrong with SE114!

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