What If Top Wood Grain Was Askew?

[Tom Coletti]

A bizarre question, but I was curious as to what you think would happen if the top wood in an acoustic instrument was built with the grain not parallel to the strings.

So if the top grain is usually patterned like this ||||||||

What do you think would happen with the tone or stability if the grain of a 2-piece top was patterned like any of the below? And what else do you think would have to change with the design of the instrument to accommodate these weird wood grains?

1. V-pattern towards tailpiece \\\\\\///////

2. Diagonal pattern \\\\\\\\\\\\

3. V-pattern towards neck //////\\\\\\\

4. Perpendicular to strings =========

To me the diagonal pattern seems like it might be an interesting experiment for a fanned-fret instrument, as this grain direction would put the skewed bridge perpendicular to the top grain, but other than that I have no idea what these would do, except perhaps just collapse the top.

[BrianWilliam]

https://m.youtube.com/watch?v=JmzuRXLzqKk

[John Soper]

Why doe you think Gibson used sunburst or black finish on many guitars & mandolins? To obscure visual flaws in their instrument tops...

Not sure I've ever seen perpendicular wood grain on a top, but... I've heard plenty of great sounding instruments that didn't have book matched straight grain tops and plenty with the grain a
t a slight angle.

[Paul Busman]

I think one of those V patterns could look terrific if the top had a nice pronounced grain. I can't imagine it making a huge difference, but I'm not a luthier.

[multidon]

If a harp has a solid spruce soundboard, it is generally built in glued together sections with the grain running side to side. This is partly a structural thing, with all that string tension pulling upwards, but I never heard anyone say the sound suffered in any way.

There was a thread a while back about a used Weber Gallatin that was for sale with a pronounce wavy pattern in the top grain. It sold quickly and many here were fascinated with the look. Some thought it reminded them of some old Gibson tops. My wife has an old Martin 1 series 000 guitar with wavy grain. It sounds just fine.

If wavy grain and perpendicular grain sound fine, I don’t see why any of the other patterns above wouldn’t sound fine too. But you also have cosmetic considerations and structural considerations. Seems to me the grain running true and straight up and down would be stronger, and it looks good too. Very few people want an instrument that looks odd and nobody wants one that self destructs because it’s not strong enough to support the string tension.

[sunburst]

This \\\\\\\\\///////// and this /////////\\\\\\\\\ represent grain run out at the glue joint, and that means the glue joint is weaker, so those are not good ideas structurally.
As for sound, likely no discernible difference attributable to grain direction.

[Seter]

I've seen the V shape in laminated tops with exotic woods but I suppose that's another kettle of fish. Didn't someone post an instrument with a checkerboard top, or maybe a four piece puzzle piece top? It might have been a back.

[Magnus Geijer]

This is my #4, which I built basically from discarded parts from #1-3. Somewhat irritatingly, it's probably the best sounding 4-string I've built.

[Jim Hilburn]

If you think about it, getting //////\\\\\\ isn't possible in a bookmatch without reversing one side. You end up with ////!/////.

[Jim Garber]

This 1882 Tilton guitar has the topwood running diagonally. I have seen many, but not all, of Tilton's guitars with that feature.

[Bob A]

Tops are usually split off the same billet. You'd be wasting a fair amount of wood to try for a \\// match. Of course, it depends on the grain in the chunk of spruce you're working with.

Insofar as placing the grain parallel to the bridge, seems to me there'd be structural issues; I can envision the top splitting in two beneath the bridge, breaking along the grain.

[Tom Coletti]

Very informative responses, thank you. And that 4-string looks exquisite, Magnus, the body looks reminiscent of a Rigel 2-point.

The 1882 Tilton that Jim posted is interesting; kinda hard to tell from that photo but I'd assume the top is cut from a single piece of wood to eliminate the issue of a cross-grain glue joint, yes?

[fatt-dad]

isn't there anisotropic variation that's sort of fundamental to the way guitars are built and braced?

(I just wanted to use a big and hard-to-pronounce word.)

Notwithstanding John's point about run-out and joint strength. In principal, isn't the strength/properties along the grain different than the strength/properties transverse to the grain?

I'd expect a guitar with the top grain running transverse to sound different.

Yes, I'm an engineer.

f-d