secrets revealed!!!,,
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| bracing a soundboard??? http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=39535 |
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| Author: | superspeedo [ Thu Feb 28, 2013 1:04 pm ] |
| Post subject: | bracing a soundboard??? |
Hay all, What wood can be used for bracing a soundboard? Is there meany different types other then spruce? |
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| Author: | meddlingfool [ Thu Feb 28, 2013 1:14 pm ] |
| Post subject: | Re: bracing a soundboard??? |
Spruce is your best bet. Best stiffness/weight ratio. Not hard to get. Cheap. |
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| Author: | Alan Carruth [ Thu Feb 28, 2013 1:25 pm ] |
| Post subject: | Re: bracing a soundboard??? |
It's interesting that all softwoods follow the same rule relating the Young's modulus along the grain to the density. What this means is that if you get two pieces the same size of softwood with the same density, they will have the same stiffness along the grain within pretty good limits. Thus, in theory, you could use any softwood for bracing, so long as you take the density into account when you cut it to size. There are a couple of qualifiers, of course. 'Softwood' here is used in the botanical sense: wood that comes from trees that have needles rather than broad leaves (and a few other differences). Spruce, cedar and pine are all softwoods, but so is Douglas Fir, which can be as dense as oak. Balsa, which is a very soft wood with low density, is botanically a hardwood, and does not follow the same rule regarding Young's modulus and density. There can be a wide range in toughness between softwoods, too. Spruce tends to be notably tough: it resists splitting pretty well. WRC, Doug fir, and redwood don't. I tend to avoid using splitty woods for bracing. Most of the overall weight of the completed top is in the top, with the bracing frequently being less than 25%-30% of the whole. Given that a denser softwood will give the same stiffness with a smaller cross section, you can save some weight by tailoring the braces to the wood properties, and end up not adding too much weight to the top even if the brace wood is fairly dense. The belief in 'magic wood' is just as strong for bracing as it is for tops, and many people will say that you _must_ use (spruce name here) bracing to get the best sound. I think that would be a tough one to substantiate in blind listening tests. I know some very good makers who hang around the local lumber yard and thumb through the 2x4s when they need brace stock. You have to have a good eye for what you're looking at, but with some practice you can get great wood that way. I've also made some good finds in old buildings that are being torn down. I got a bunch of Red spruce some years ago from a covered bridge over the Connecticut river that was being renovated. The wood had been cut on Mt. Ascutney in Vermont in 1869, and some was extensively treated with the Luthier's Secret Ingredient: horse piss. Good brace stock is where you find it. |
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| Author: | weslewis [ Thu Feb 28, 2013 1:40 pm ] |
| Post subject: | Re: bracing a soundboard??? |
| secrets revealed!!!,,
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| Author: | Jeff Highland [ Thu Feb 28, 2013 2:57 pm ] |
| Post subject: | Re: bracing a soundboard??? |
Two different posts on this, are you hoping someone will agree with you on using cedar this time? |
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| Author: | superspeedo [ Thu Feb 28, 2013 3:16 pm ] |
| Post subject: | Re: bracing a soundboard??? |
Wow! That is the best answer i have had yet, i love hearing about the history that goes behind it all. There is so much to and a life time dont seem long enough.. So could i say put the x brace as spruce and then put the rest of the bracing as cedar?? Thanks Alan i really liked what you gad to say, a man that knows what he is talking about!!! |
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| Author: | bluescreek [ Thu Feb 28, 2013 3:26 pm ] |
| Post subject: | Re: bracing a soundboard??? |
I did use lumber for a few top braces in my early days woods that don't work Poplar Mahogany ( sounded muffled ) Blue Spruce ( actually sounded pretty good ) Norway Spruce ( sounded fine ) I use all sitka or adi now |
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| Author: | ZekeM [ Thu Feb 28, 2013 3:38 pm ] |
| Post subject: | Re: bracing a soundboard??? |
Jeff Highland wrote: Two different posts on this, are you hoping someone will agree with you on using cedar this time? I believe that was the purpose  reminds me of abraham trying to save sodom and gomorrah. If i can find just 20 people who say cedar is ok, well 15 people? 10? 5? If i can just find one person who says cedar is ok........
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| Author: | DennisK [ Thu Feb 28, 2013 4:29 pm ] |
| Post subject: | Re: bracing a soundboard??? |
Hey, if you want to use cedar, use cedar. I've used redwood despite the many nay-sayers around here. I'm a little worried to use it for the X brace on a steel string due to the brittleness of the wood and high tension placed on that brace. But for ukuleles, classicals, and other low-tension instruments, the only real danger is impacts, from dropping the instrument, hitting it with a hammer, smacking the neck into things, which can transfer the force to the upper transverse brace and crack it, etc.. Although seeing as how most instruments are handled by humans, those thing are a real concern. You could indeed use spruce for the X and upper transverse brace, and cedar/redwood for all the others. May be a little more difficult to carve the braces since the spruce ones would be stiffer for a given height, so you can't gauge by eye as well. I don't know if there's any audible effect from using different species for bracing. Probably not much, if any. But there's a certain elegance to using the same species as the top wood  And it looks nicer inside too.If you just want something that's not spruce, you could use Port Orford cedar. It's strong and tough, and smells nice too. Spanish cedar would probably work pretty well too. But there is a reason spruce is used almost exclusively... no other wood has a clear advantage over it for this application, and most have a clear disadvantage. |
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| Author: | Trevor Gore [ Thu Feb 28, 2013 5:23 pm ] |
| Post subject: | Re: bracing a soundboard??? |
There's a fairly extensive analysis in "the book" comparing different brace woods, their stiffness to weight and their typical fracture stresses; p. 4-50 for those interested. There's a reason that spruce is (and always has been) the preferred choice. For typical brace geometries, it's lighter at the same stiffness then just about any other common wood, whilst not exceeding its stress limits under typical guitar type loading. |
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