Official Luthiers Forum!

A friend sent me the following link to Dick Boak talking about tenor guitars and in it he mentions that Martin always joins the tops of their guitars with the wide grain along the center seam and the tight grain at the edges. This is the opposite of what I learned and what I found in several other well known texts. Personally I want the stiffer grain in the middle and the top more loose around the edges thereby allowing the top to act as a diaphragm of sorts and pump more air. I think this would vibrate the top over a wider area in a more consistent manner, but what do I know? Of course your top bracing can nullify either a stiff or a loose top. I also thought Dick’s comment about using wide grain on Mahogany guitars and tighter grain on Rosewood guitars particularly interesting.

I'm very interested in hearing what everyone thinks about this.

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Chuck

First of all, tight grain is not necessarily stiffer than wide grain. I generally join the tight grain, but that is because of the method used to cut the tops.
I believe Martin started the practice of joining the wide grain when they were using red spruce cut from long logs. In that case, tops cut from a tree with spiral will have the least runout on the heart edge of the top....which is usually the wider grain.
However, cutting tops from short split billets allows the minimal runout to be shifted to the bark edge (tighter, grain, usually).
I like joining the bark edge for another reason.....the tops generally have less defects there. Today's red spruce is generally cut from minimal-sized trees, and the heart often contains pin knots and heart checks. Also, the smaller growth ring radius in the heart means that that edge of the top will more likely be off-quarter, which does affect cross-grain stiffness.

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John

I've always joined the tight grain edge without really knowing why. Just thought it looked better. Thanks John, great post.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

When talking about the tops he specifically mentioned that the stiffer grain was at the edges and this allowed more movement of the top in the middle increasing bass response.
Makes sense.
At least they were doing something for tonal reasons instead of trying to avoid warranty work.

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Old growth, shmold growth!

Medullary rays and bear claw show closer to the center or tight grain. So one of the reasons for jointing the tight grain.
Sonically me prefer the tight grain around the perimeter just like in old Martins.
So for me it depends on the woods visual effects ~ showing off the rays or bear claw instead of sawing it off...no rays or claw, then I join the wide edges.
Grain count has no effect on stiffness.

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Hi Filippo,
You will hear some people say "the tone is in the wood", which I take to mean that you need to leave enough wood in the soundboard to produce enough overtones to give the guitar a good sound. To say a guitar sounds "thin" I think refers to the banjoey sound an overly thinned top will produce. Bracing can help, but I don't think it can always overcome a bad quality top. YMMV

I've joined tops with either the wide grain in the center or at the edges. If there is a wide variation in the width of the grain I usually put the wide grain out, but most of my tops have pretty evenly spaced grain lines.

I join tight grain because I believe it's easier to hide the glue joint personally.