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J-45 top seam/join line


john e cage

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Do you mean that the top joint is visible because the two sides of the top look different, or because the seam itself is visible as different from either half of the top?

 

Because the tops are book-matched--made by splitting a thicker piece of wood into "leaves" that are folded open like pages of a book, then joined together--the two sides may reflect light quite differently due to grain run-out.

 

This is not really a flaw, and has no measurable impact on the tonal characteristics of the guitar, or its value.

 

If you mean that the seam itself is very visible, we would need to see a picture to know exactly what that means.

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Probably described it wrong. I don't see the seam itself just differences in the color? of the wood where they are joined resulting in a visible line.

 

Do you mean that the top joint is visible because the two sides of the top look different, or because the seam itself is visible as different from either half of the top?

 

Because the tops are book-matched--made by splitting a thicker piece of wood into "leaves" that are folded open like pages of a book, then joined together--the two sides may reflect light quite differently due to grain run-out.

 

This is not really a flaw, and has no measurable impact on the tonal characteristics of the guitar, or its value.

 

If you mean that the seam itself is very visible, we would need to see a picture to know exactly what that means.

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... I don't see the seam itself just differences in the color? of the wood where they are joined resulting in a visible line.

 

This is what a I thought you meant. Again, it's not a problem unless the cosmetic aspect of the way it looks bothers you enough to dislike it.

 

 

.

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As Nick mentioned, what you are describing is commonly referred to as grain runout. If you look at the grain where it's visible through the soundhole, it ideally should be straight rather than tilted. A straight cut will lessen the possibility of visible runout.

 

I greatly prefer having a well matched top with minimal runout, but it's strictly a personal preference. That said, it does impact my interest in any instrument I might consider purchasing.

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Can't imagine it's more than cosmetic,

 

In Guitar Geek theory it is. The main argument is that tops which display run out are less stiff than those without it. So essentially is would be considered a structural issue.

 

But hey, runout happens. Even though it is easily seen in the wood before it is fashioned into a top the Gibsons and Martins of the world do not seem to give it much thought. Strangely the best sounding guitars I own have the worst looking tops. So go figure.

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I think it's more noticeable on sunburst tops like a J-45 than a natural top. Can't imagine it's more than cosmetic, but looking at dealer websites where they have several of the same model, the ones that blend together better really look better.

This may be pure co-incidence..but I just purchased a used 2005 Gibson Hummingbird Artist...beautiful condition, well kept, no stress marks at all, almost zero fret wear, no bulge in top, perfect neck angle, it appeared clear that it had been humidified over the years as it was really in good shape...but when it arrived..it had that unsightly soundboard line so often found in Gibsons, where the two top halves meet (in did not show in the sale photo)..I was delirious with pleasure and intended to keep it anyway since the price was right.

 

.....that is until I looked much closer at the point where those unsightly "cosmetic top sound board lines" met...and there was a perfect hair line crack, almost invisible, following that exact joint line below the bridge, spanning about 4 inches down the top. Perhaps it was pure co-incidence....and I returned it without any problem for a full instant refund from GC, so there was no problem, and no money lost, not even taxes and shipping.

 

But it left me wondering how often this occurs, and if this is more prevalent in the cosmetically mis-matched tops. Having owned 27 other fine guitars..most with no cosmetic line as I rarely buy them that way..none of them ever cracked in that book matched spot on the top, even after many years.

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.....that is until I looked much closer at the point where those unsightly "cosmetic top sound board lines" met...and there was a perfect hair line crack, almost invisible, following that exact joint line below the bridge, spanning about 4 inches down the top. Perhaps it was pure co-incidence....and I returned it without any problem for a full instant refund from GC, so there was no problem, and no money lost, not even taxes and shipping.

 

But it left me wondering how often this occurs, and if this is more prevalent in the cosmetically mis-matched tops. Having owned 27 other fine guitars..most with no cosmetic line as I rarely buy them that way..none of them ever cracked in that book matched spot on the top, even after many years.

 

I believe this is pure coincidence.

 

Having worked with wood for almost 50 years in furniture making and boatbuilding, in my experience there is no reason to believe that differences in grain run-out between two pieces of wood joined together should create a joint more susceptible to cracking. In the case of book-matched woods, they are from the same wood flitch at the same humidity, and with the same grain pattern in mirror image.

 

The joint in a guitar top is very small: no more than 1/8" (just over 3mm) thick. There is very little gluing surface. It depends completely on the perfection of the glue joint, the structural integrity of the glue, and relative stability in the environment to keep from failing. There is no cleat backing up the joint, as there is in the back, with its glued centerline back strip. To my mind, it's a miracle more of them don't crack.

 

You could also get a lacquer crack along this joint which might not impact on the integrity of the glue joint itself.

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I believe this is pure coincidence.

 

Having worked with wood for almost 50 years in furniture making and boatbuilding, in my experience there is no reason to believe that differences in grain run-out between two pieces of wood joined together should create a joint more susceptible to cracking. In the case of book-matched woods, they are from the same wood flitch at the same humidity, and with the same grain pattern in mirror image.

 

The joint in a guitar top is very small: no more than 1/8" (just over 3mm) thick. There is very little gluing surface. It depends completely on the perfection of the glue joint, the structural integrity of the glue, and relative stability in the environment to keep from failing. There is no cleat backing up the joint, as there is in the back, with its glued centerline back strip. To my mind, it's a miracle more of them don't crack.

 

You could also get a lacquer crack along this joint which might not impact on the integrity of the glue joint itself.

Thx Nick, that was helpful information.

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The top on my J45TV center line is all most invisible

I've also had many years working with wood. The last 20

in the architectural wood door industry

 

 

I probably didn't phrase that well. The wood of the top at the joint is no more than 1/8" thick. The joint itself is, and should be, virtually invisible except for differences in reflected light between the two pieces of the top. Neither Tite-bond nor hide glue have significant gap-filling structural characteristics. The strength of the joint is largely dependent on wood-to-wood contact. The less glue, the better, provided the joint is not dry (starved of glue).

 

There will almost always be differences in the way the two pieces of wood reflect light, which can look as if the one piece of wood is lighter or darker than the other. This is perfectly normal, and not a flaw. If you don't like the look of it, find a top where the differences are less obvious.

 

I probably would not accept a new guitar that had a finish crack at the top joint, unless I could confirm that the joint itself was sound.

 

But I've never bought a brand-new guitar.

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Run out, bear claw, silking... won't effect anything except from an aesthetic aspect. Some buyers love (and some don't) run out, bear claw and/or silking. You are the only one that matters. For me, it's all about the tone. Action and playability can be adjusted - tone can not.

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In some cased I wonder if it is the how the stain takes in the joint. A couple factors may be involved: the amount of glue absorbed by the edge face of the pieces of wood, the dryness of the wood at the time of spraying. I have seen some Gibson sunburst that have the line with no grain runout. The grain is straight and parallel, perpendicular to the bodylines, or parallel to the neek. As the guitar ages and the grain lines darken the seam line may blend in more and become less distinct.

 

chasAK

 

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With the risk of being a little controversial, I'll say that not even a thin crack between the 2 halfs would have vital influence on sound (if any).

 

Yes, I can feel the thunder rising ;-)

 

But one of my Martins had a slim seam-crack from bridge to bottom that - like a shop that rents ice-skates - opened during winter and closed by early summer, and several luthiers told me to leave it like that as there was a chance the braces would be dissatisfied with a repair now that they were used to the flexibility.

 

However I chose to disregard that and managed to fix the gab with wood-filler (then right-colored paint).

Originally intended to approach it from below, but as that was too difficult, I miniature-worked carefully from above.

Yes, it took a toll on the lacquer if one look from certain light-angles, but no serious probs ever occurred.

Sound-wise there were no difference the woods just vibed on. .

 

But I've often wondered.

 

Why 2 pieces in the first place. Is it all about the normal tree-sizes.

And what would happen sonically if a top (and a back for that matter) came in 1 whole piece of sliced timber.

Guess not even the most skilled scientist would ever be able to answer as all woods differ.

Then again maybe after making 25 of each there would be a pattern. .

 

 

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