Question about one piece or bookmatched tops.

I'm curious about what determines whether a top is one piece or bookmatched. Spruce and mahogany are usually one piece, but koa and acacia are usually bookmatched. Is this a strength issue? I would think one-piece tops are stronger than bookmatched because there is no joint that can split. Are some woods more amenable, grain-wise, to bookmatching than others? Is it based on the natural girth of the tree? Smaller logs require book-matching while larger logs allow for one-piece tops?

You will get some answers from people more knowledgeable about uke construction, but having built custom hardwood furniture, it depends on the girth of the tree foe one. For another, highly figured woods often look much more pleasing and even being bookmatched.

As to strength, a good glue joint is actually stronger than the wood itself. I've actually tested that by gluing to pieces of wood together at 90 degrees angles, clamped, let dry and tried to break the glue joint. The wood will splinter around the joint, but the glue joint will remain.

No, spruce and mahogany are not "usually one piece". What you'll find is that with the smaller ukes...concerts and sopranos especially...the width is narrow enough to use good one piece tops. For wider instruments, it's harder to find good appropriate one piece tops (or backs), and so we bookmatch. Violin backs can go either way, and as long as the wood chosen is great, there's no penalty; many very expensive violins have one piece backs...but they almost always have bookmatched tops. We almost always build our Compass Rose ukes with two piece tops and backs, though I usually teach my "build a uke" course with one piece tops and backs. Just depends on what I have in the way of material. There's no tonal or structural difference as long as the wood is chosen well.

It's not about the wood as much as the size of the instrument.

I doubt if an instrument cares much about wood joints, but humans are used to the symmetry of book matched wood. On larger instruments the plates may be more uniform in all characteristics with a book match, rather than one piece that stretches 16" across. Not to mention the logistics involved in freighting wide planks or resawing them into sets. With ukes it could easily go either way, but we are symmetrical animals and symmetry pleases us. Look how hard it is for many to accept the looks of a cutaway instrument.

I do bookmatched tops and backs because I can't resaw anything more than 6" inches.

I've often heard that it makes no difference, but when we did custom instruments, my partner Omar (the true luthier in our enterprise) politely responded to a request for a one piece top like this (translated):

"Of course we will do whatever the Senor desires, but please tell him it won't sound as nice".

Bear in mind, that my partner comes from a background of Classical Concert Guitars and Cuatros, but his feeling was that sound waves follow the grain, and that with bookmatching the sound is more balanced.

I've heard the argument that while this may have merit, the difference is only noticeable on a larger instrument. As everything we build is bookmatched (I know when the polite tone actually means "are you out of your mind?"), I couldn't say for sure.

There is no sound difference... I prefer 1 piece wherever possible.

There isn't any sound difference that I can hear....I much prefer a book match.

And there you have it. Two entirely different opinions from two very...very good builders...neither of whom are right or wrong about this, though they state positions almost 180 degrees apart.

Is there an absolute truth in this?

NO!

RT

Thank you to all who gave their opinion and knowledge to answer my question.

It's good to know that a uke with a bookmatched joint is just as strong as a uke with a one-piece top.