Official Luthiers Forum!

I just participated in the Topic of buying lumberyard wood. A lot was
mentioned about Quartersawn lumber for the backs and sides. I have
only made a few guitars and all mine have used Quartersawn wood or
almost quartersawn. But I have some quilted mahogany, birdeye maple
and killer ziricote that is not cut on the quarter. And I am sure that the
pros on this forum wouldn't bat an eye at using this type of timber in a
guitar.

So, what is the secret to using wood that is not quartersawn. Does it have
to age longe. Does it have to be braced differently? I am curious.

Please advise.

Ken

If it's resawn close to final thickness and it doesn't go nuts leaving it around your shop for a while, it'll probably be OK.   Beware of potato chip inclined wood, though.

Ken,

Not a bad idea to consult a table of wood shrinkage, and check the "tangential shrinkage" value. That's the value for flatsawn wood ("radial" is for quartersawn, and you have to extrapolate for boards that are rift or where the grain orientation changes across the board.) Though I know some luthiers won't touch quilted Maple, others will, and it does seem relatively stable in completed instruments. So, you could use the tangential shrinkage values for Bigleaf Maple (Acer macrophyllum, 5.7% shrinkage at 6%MC) as your yardstick of what will probably be stable enough. Birdseye Maple is usually Sugar Maple (Acer saccharum) and has a relatively high (7.6% shrinkage at 6%MC) tangential shrinkage compared to Bigleaf, so I would be afraid to use it in an instrument with a wide back.

Mahogany is generally very stable even flatsawn. The flatsawn Ziricote is a bit of a crapshoot, IMO.

No matter how long you season the wood, it may become a bit "tamer", but it will still expand and contract with changes in atmospheric moisture. The exact amount each board will change in width is no doubt variable from tree to tree and board to board, and someone here pointed out to me not long ago that kiln drying values for shrinkage do not accurately predict the exact amount a specie will expand and contract in service - but it is a strong hint.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

More important in some respects is how much curvature the ring lines make as seen on the end grain. As wood dries out the difference between radial and tangential shrinkage tends to make those ring lines want to straighten out: that's why lumber often warps and cups. Dead quartered or dead flat cut wood won't warp, but to get really dead flat cut you'd need to find a tree of infinite radius. Pieces where the grain angle vaies from oneplace to another will have more tendancy to ripple and cup, and you may need to leave the sides thicker, for example, so that you can sand that out after bending, if that sort of thing bothers you. I just think it's part of the charm of the wood, but I'm probably in a minority there. The ideal seems to be the look of good sheet metal, like a new Lexus.

"I just think it's part of the charm of the wood, but I'm probably in a minority there. The ideal seems to be the look of good sheet metal, like a new Lexus."
I like that analogy Alan

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Thanks for the information. I need to do my homework

Ken

[QUOTE=Alan Carruth] More important in some respects is how much curvature the ring lines make as seen on the end grain. As wood dries out the difference between radial and tangential shrinkage tends to make those ring lines want to straighten out...[/QUOTE]
A very good point regarding the wood's planar stability.

[QUOTE=Alan Carruth]...dead flat cut wood won't warp...[/QUOTE]
But it will still shrink, and if the tangential shrinkage rate is high and the instruments back is wide, that instrument's back is much more likely to crack when the RH dips. (Not quibbling with you Alan, just trying to underscore why some flatsawn wood requires careful consideration to make sure the instrument meets longevity goals.)

Dennis

_________________
Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

What Al is basically saying is that because trees are more or less round, the only way you're ever going to see really flat flat sawn wood is if the plank is narrow enough that the annual rings are virtually flat looking at the end grain.   And given that a lot of us make bolt-on electric necks with flat sawn stock, it's not so bad if it isn't very wide.   But try to get truly flat flatsawn guitar back material, and you're going to be fighting it a bit.