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There has been many discussions about wood for the top and B&S but seldom about the braces. I know its important to use perfectly quarter sawn or hand split wood but what about the type of wood used? The commonly used wood are spruce but what about other wood like mahogany etc. I have used mostly non traditional wood and it gives a variety of tonal colours. I know some makers do weigh and test its flexibility, I tap my braces for nice clear ringing tone before I glued them to the top. What do you all think? Jeff

I think the most important part of your question is the well quartered part. The more on the vertical the grain the better and more consistent the strength of the brace in that plane.

Ervin Somogyi did an experiment with a bunch of bracewood and came up with some different conclusions.  It's written up in an article somewhere (American Lutherie, I believe) and I thought it was on his site but couldn't put my finger on it.

As I recall, he did the testing after he noticed that some of his go-bars were much stiffer than others and that it did not correspond to common thinking about grain direction.  If memory serves, he found that the stiffest grain orientation was different in relation to the density of the piece (although I don't remember off the top of my head how it corresponded). Some wood was stiffer quartered, some was stiffer with angled grain, some was stiffer flat sawn, depending on density.

While flatsawn can indeed be as stiff, the problem arises because we either scallop them, or at least taper the brace ends where they meet the ribs. That act, on fat sawn woods, introduces a stress riser and can easily split the brace between growth rings.

I wouldn't use flat sawn for solid braces either but only based on intuition, not any testing.  I mentioned that to Somogyi and I don't recall him giving an opinion.  It does seem like a fine option for CF laminated braces and a good potential use of top cut-offs.

I did find a copy of the article though and his basic finding was as follows:

Grain orientation "seems" to have more of an effect on stiffness/deflection in spruce as the density of the pieces decreases. Deflection in dense spruce seems to be similar regardless of grain orientation.  As the pieces get less dense, grain orientation matters more and stiffness seems to decrease the closer you get to quarter sawn.

He also acknowleges that his results were surprising and suggests that more testing could be done.  And he states that he isn't recommending one way or the other, just reporting the results.

I'm really surprised that no one has yet observed that every piece of wood is different.

Yes, the USDA can issue statistics that show that, ON AVERAGE, spruce has an excellent strength-to-weight ratio. THE COMMON WISDOM has it that vertical grain is a good visual clue to the likelyhood of strength. Ditto with number of grain lines per inch.

But these averages and generalities. As sure as there is studly Sitka spruce, there is also wimpy Sitka. Seems kinda optimistic to me to trust reputation and appearance in lieu of some actual testing.

For my part, I have measured the weight and deflection of the bacewood in my most recent build, and wouldn't you know it, some samples deflected less than others with the same weight. This presents a pretty easy call: use the stronger stuff!

One thing that puzzled me was that, for the specific pieces that I tested, the more late grain lines, the stronger_BUT ALSO HEAVIER_the brace was.

I'd really like to know which to use "stronger but heavier" or "lighter but weaker".

Better still, is there a more useful test for bracewood, than deflection testing?

Larry