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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?

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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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

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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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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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

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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Canada

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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John

Thanks for the reminder on a great tutorial Shane.

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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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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http://www.sixgunguitars.com

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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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

BINGO! Though there are many examples of flat sawn braces in history.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

[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.

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 think the point is that turning the block 90 degrees eliminates runout.

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John

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.
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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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

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.

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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John