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| Author: | TJGraham [ Wed Mar 09, 2011 11:04 am ] |
| Post subject: | Bracewood |
I'd like to start making my own bracewood. Does anyone have reliable dimensions for top and back bracing that I can cut from 22x2x3/4 pieces? |
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| Author: | Colin North [ Wed Mar 09, 2011 11:20 am ] |
| Post subject: | Re: Bracewood |
Depends. Are you talking wood which has been split on two sides at 90 degrees first to avoid runout? If there's any runout you could be lucky to get finger braces - ask me how I know! |
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| Author: | David Newton [ Wed Mar 09, 2011 2:25 pm ] |
| Post subject: | Re: Bracewood |
Buy bracewood in as large a block as you can, and split it with a big knife. Sounds like your bracewood is already cut to size, and will yield 2, braces per piece. Test one piece, try to split it into 2, 1" tall pieces. If it runs out, you'll know. |
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| Author: | Dave Fifield [ Wed Mar 09, 2011 3:18 pm ] |
| Post subject: | Re: Bracewood |
From all I have read (almost everything that's been published) on lutherie in the last 20 years or so, it makes no difference at all if you use braces that have vertical grain or horizontal grain. Ervin Somogyi and others have scientifically proven this beyond all reasonable doubt IMO. So, if you have some quartersawn brace wood that has a bit of runout in it, why not just use it horizontally? Should be just fine. It might not look as good as a perfectly quartered piece with no runout, but it should have exactly the same structural properties. Why waste wood unecessarily? Dave F. |
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| Author: | Shane Neifer [ Wed Mar 09, 2011 6:52 pm ] |
| Post subject: | Re: Bracewood |
There is some information that I put together a while back on bracewood. You might find it useful. It is in the Tutorial section. Follow the link below. http://luthiersforum.com/forum/viewtopic.php?f=10117&t=24665 Good Luck! Shane |
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| Author: | John Arnold [ Wed Mar 09, 2011 9:58 pm ] |
| Post subject: | Re: Bracewood |
Quote: From all I have read (almost everything that's been published) on lutherie in the last 20 years or so, it makes no difference at all if you use braces that have vertical grain or horizontal grain. In general, slab cut braces are slightly stiffer. You can prove this by crafting a test brace with a perfect square cross-section, and seeing which vibration direction produces the highest pitch. |
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| Author: | Darrel Friesen [ Wed Mar 09, 2011 10:23 pm ] |
| Post subject: | Re: Bracewood |
Thanks for the reminder on a great tutorial Shane. |
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| Author: | David Newton [ Wed Mar 09, 2011 11:24 pm ] |
| Post subject: | Re: Bracewood |
I'm not going down the road to argue for or against gluing the braces vertical or flat sawn to the top. My experience, in flexing brace wood in my hands, sawn compared to split, is that split wood flexes without twist, whereas sawn braces, if they have significant runout, flex with a twist to them. Brace wood that twists when I flex it, doesn't feel good. If a piece of brace wood doesn't feel good in my hands, I don't want to use it. For all I know, braces that twist when flexed will make a better sounding guitar than braces that resist twisting. |
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| Author: | Brian Forbes [ Thu Mar 10, 2011 2:15 am ] |
| Post subject: | Re: Bracewood |
That brace block you have sounds like the ones that you get from stew-mac or grizzly. You should be able to brace an entire soundboard with it, if you are using a tall skinny bracing strategy. The Cumpiano method will need 1.5 of those or more to accomplish the bracing, especially if you are sawing the pieces off and losing 1/8" every time you cut it to the saw kerf. I use tall skinny braces that are 5/16" wide for the X, and UFB, and 1/4" braces for the SHB's, LFB's, and FB's. This can all be taken from one piece of that same size block. As far as the flat/quarter/runout argument, I'm not going to touch it, I don't have any real experience one way or another. I always rip saw from a quarter sawn blank, and have never had an issue with it. That being said, I can see the theory behind splitting instead, so I'll just call it a tie. |
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| Author: | Laurent Brondel [ Thu Mar 10, 2011 9:18 am ] |
| Post subject: | Re: Bracewood |
Stiffness is the main, but not the only one, requirement for braces. Split resistance is another one, and that's the reason vertical grain braces are generally used. Unless there is runout, they will not split the way flat sawn braces can. |
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| Author: | WaddyThomson [ Thu Mar 10, 2011 10:25 am ] |
| Post subject: | Re: Bracewood |
BINGO! Though there are many examples of flat sawn braces in history. |
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| Author: | Barry Daniels [ Thu Mar 10, 2011 11:02 am ] |
| Post subject: | Re: Bracewood |
[quote="Dave Fifield"]From all I have read (almost everything that's been published) on lutherie in the last 20 years or so, it makes no difference at all if you use braces that have vertical grain or horizontal grain. Ervin Somogyi and others have scientifically proven this beyond all reasonable doubt IMO. So, if you have some quartersawn brace wood that has a bit of runout in it, why not just use it horizontally? Should be just fine. It might not look as good as a perfectly quartered piece with no runout, but it should have exactly the same structural properties./quote] Dave, you are confusing runout with grain orientation. They are not the same and the difference is very important. Also, the structural properties are not exactly the same. Re-read Ervin's research and you will see that he found a fairly wide range of stiffness in the different samples. |
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| Author: | John Arnold [ Thu Mar 10, 2011 12:27 pm ] |
| Post subject: | Re: Bracewood |
Quote: Stiffness is the main, but not the only one, requirement for braces. Split resistance is another one, and that's the reason vertical grain braces are generally used. Unless there is runout, they will not split the way flat sawn braces can. Actually, the split resistance is better with flat sawn braces, because the weakest plane is perpendicular to the growth rings. The next weakest plane is parallel with the rings, meaning that slant grain should be best for split resistance. Quote: Dave, you are confusing runout with grain orientation. I think the point is that turning the block 90 degrees eliminates runout. |
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| Author: | Laurent Brondel [ Thu Mar 10, 2011 12:44 pm ] |
| Post subject: | Re: Bracewood |
WaddyThomson wrote: Though there are many examples of flat sawn braces in history. Bouchet liked his UTB to be flat sawn, and of course lutes have flat sawn braces. However, most guitars tend to be braced with vertical grain bracing.John Arnold wrote: Actually, the split resistance is better with flat sawn braces, because the weakest plane is perpendicular to the growth rings. The next weakest plane is parallel with the rings, meaning that slant grain should be best for split resistance. I will disagree with you John. In absolute terms you are right. However for braces glued to a plate there is very little chance they would split along the grain unless there is severe runout, the plate acts as a laminate. However flat sawn braces always run the risk of splitting along the grain (horizontally), especially starting at the ends where they are traditionally tapered or scooped.
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| Author: | John Arnold [ Thu Mar 10, 2011 2:04 pm ] |
| Post subject: | Re: Bracewood |
Quote: However for braces glued to a plate there is very little chance they would split along the grain unless there is severe runout, the plate acts as a laminate. I don't see how the top acting as a laminate has anything to do with cracked braces. Maybe you are confused by my terminology. The most likely way for braces to split is the short way.....parallel with the plane of the top. That is also the weakest plane with QS braces. Quote: However flat sawn braces always run the risk of splitting along the grain (horizontally), especially starting at the ends where they are traditionally tapered or scooped. Generally, braces split at two places...at the scoop on the end, or in the notch where the X-braces cross. I personally have repaired hundreds of cracked braces, and nearly all of those were QS. Some had runout, but most did not. |
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