Different bracing wood species

[TomBicknell]

Hi all, I'm interested to hear people's experiences with different wood species for acoustic bracing, either falcate, x bracing or other traditional patterns.

In particular, I'd love to hear how Australian natives work for bracing, such as bunya, King Billy pine, Australian red cedar etc, and also from anyone who's used hardwoods for back (or other) braces.

If you're using traditional spruce or cedar, what variety and why?

[kiwigeo]

I've always stuck to spruce..light and stiff.

King Billy pine...only wood that Ive actually tested for stiffness. The stuff is si variable its risky using it without testing actual stiffness.

[TomBicknell]

Do you know if there's any visual indicators of stiffness with King Billy, Martin? Apart, of course, from the obvious quartersawn grain, free of knots etc.

[TallDad71]

I've always followed the advice to make sure the grain direction of the spruce is vertical relative to soundboard.

When I knock up a batch of braces I take a blank 8mm x 12mm x 50mm and subject it to deflection testing with a 1Kg weight on the end, its remarkable how much variation there can be between batons.

More recently I have tended to cut the blanks into 2.7mm x 12mm strips and then laminate three together, usually turning the middle laminate upside down to give a slightly different grain orientation. I find this gives more consistent results in deflection tests. I have even taken to using a different wood, western red cedar, as the core, but this is just for prettiness.

I laminate whether for both Falcate and straight braces.

[TomBicknell]

Do you have a preference for a particular species of spruce, Alan?

[peter.coombe]

You left out Red Spruce, i.e. Adirondack Spruce.

[TomBicknell]

Oh yes, my bad! Not sure if I can edit the poll without losing everyone's votes - Martin?

[Mark McLean]

There is a good reason why spruce (of various sub-types) is the timber most often used for soundboard bracing. I wins, by a significant margin, in the weight:stiffness ratio comparisons. We want a braced soundboard to be stiff so that the string tension will not fold it in half. On the other hand we want it to be as light as possible so that the string energy will get it moving, and pump air, and make sound. A solid body Telecaster is really stiff and resists string tension well - but doesn't sound very good unamplified.

Spruce is also good for soundboards for the same reason - but it can look a bit boring! After you have made a few spruce-topped guitars you might have an urge to make something that is not so vanilla. Maybe make a soundboard made out of a hardwood like blackwood/walnut/mahogany/koa/maple/whatever - but then you will have more weight, which will kill volume and tonal richness. So if you make your hardwood soundboard thinner you can lose some weight but then you will really rely on the bracing to bring the stiffness back. Can't beat some sort of spruce to do that job. Anything else will be less effective. I am happy to play with different soundboard timbers but always fall back on spruce as the best bracing. If you have a strong yearning for indigenous timbers then I understand that King Billy is probably as close as you can get to imported spruce - but it is not as stiff.