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Quick Spruce Question


knockwood

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A friend of mine tried that once. He tripped and landed wrong against a stair. You can probably guess what happened...

 

 

I knew that guy... blind... you know until he tried that whole stair thing again. He can see now, but you know there is the whole paraplegic thing...

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Most of the spruce logs that are used to make guitar tops are way huge compared to the size of a guitar...It's not like they are felling trees that are 20" in diameter, obtaining 10" billets from that and making 8" bookmatched tops....

Wiki lists the trunk diameter of sitka trees to be as high a 5-7 METERS....Given that a meter is 39" that's a lot of wood...it's not like rosewood and rare hardwoods where you are skirting the sapwood to get usable tonewood.

Which actually lends to the question: Why do we bookmatch tops at all? If 20" wide spruce billets are easily available, why not avoid all this hassle of joining tops? I think it's partially due to tradition from Martin and other manufacturers who did it when dealing with red spruce...that's smaller...and also for reasons of storage/processing and maybe the stability that a bookmatched top might have by evening out any warps or imperfections in tops. Also, it's probably a lot more difficult to find a sitka log that has evenly spaced and tight grain over an entire 16 inches with no defects. At 15 lines per inch and 8 inches that's 120 years of growth with exactly the same rainfall, no fires or other problems to vary the grain in funny ways or cause defects...A lot of wood would have to be rejected for cosmetic reasons.

When you bookmatch a top, even if the grain width varies...you can have it widen out in the periphery and it still looks symmetrical and nice.

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That's pretty much the average once you figure in the variable number of growth rings (15 - 25) per inch and allowance for waste during book matching and trimming.



I just measured the number of rings per inch on one of my wider-grain spruce tops. It was about 14 per inch.

The paper that indicated growth of .3cm/year would imply about 8 rings per inch.

So the growth of riparian trees appears to be almost twice as fast as non-riparian trees.

I revise my 135 year estimate to 270 years. :)

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