Official Luthiers Forum!

Never mind. I should have read this a little better. Since I haven't gotten a response, you guys must think I'm an idiot for asking this one. Perhaps I worded it wrong. I know that wood moves forever due to rise and fall of humidity but what I don't know i show this will show up using less than perfectly quartered, straight grained wood. Everyone likes figure, well most people anyway. I do for sure and when I order my first set, I'd like it to look like the sets that you're saying I shouldn't use. I will resist that urge but I'd like a little more information on the subject anyway.

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Hutch

Get the heck off the couch and go build a guitar!!!!

Braces do have a structural role, but they can't prevent this shrinking and expanding, especially not in the middle of the free spans. Since flatsawn shrinks about twice as much as quartersawn with rosewood an ebony, it is obvious that when the humidity drops a lot, or for extended periods, there is a much larger chance of cracking for flatsawn.

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Build log

It also has some to do with the relative humidity of your build environment, and how acclimated the wood is when you build it. Wood properly dried and seasoned, and then at equilibrium to an appropriate build environment will be less prone to cracking, vertical grain or no. The braces actually simply hold the wood in place (in the context of shrinking), so if the wood is overly hydrated, then when it starts to dry, it will shrink and split at the weak grain lines, since the braces will hold the wood in place and prevent it from moving together. Wood is elastic to some degree, so some shrinking and stretching can be tolerated, how much depends on the wood, once the environment and the wood are stabilized.

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Old growth, shmold growth!

When you glue a brace across the grain, the more movement ie. expand/contract, the greater chance for glue joint failure - loose braces, or wood failure - cracks along the grain. This is minimized by the use of quarter grained wood. Most wood working situations avoid gluing across the grain, but in guitar building it is largely unavoidable.

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

I thought that issue was taken mostly care of by radiusing the backs. Now that I think of it in this light I can see I was completely wrong. Maybe if the braces were attached with rubber cement

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Hutch

Get the heck off the couch and go build a guitar!!!!

Radiusing allows for movement so that the plates don't flatten or go concave. Restricting the movement on one side is the problem and radiusing the braces is part of the remedy. I don't think rubber cement will help, but a rubber room for luthiers might help!
Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Radiusing is like a safety belt. It saves you if you hit the wall at 30mph, but not at 100...So using QS is like having airbags too

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Build log

We all build hopefully in controlled conditions and with dryed and aclimatised timber, and hope the player will store the guitar in an appropriate environment, but what performer will refuse to take to the stage because it is too dry for his guitar?
That is when the lower shrinkage of the quartersawn timber is most important