One-piece vs. two-piece top for carved Les Paul style?

[Dave Locher]

I'm looking at curly soft maple for the carved top on a Les Paul-style solidbody guitar. Is there any particular reason why I should make a two-piece top rather than a one-piece? Most guitars I've seen of this style with a figured wood have a book-matched two-piece top but as far as I can tell many of the ones with plain maple or spruce have a one-piece top. I'm guessing the two-piece top is so that they can either use smaller wood or use the part of the wood with the most figure?
I like the looks of a one-piece flamed maple top and I have found pieces big enough to do it. The question is: should I? Or is there some advantage that I'm not aware of with a two-piece top on a solidbody guitar? The top will be around 1/2 inches thick in the middle, tapering down to near zero at the edges.

[Dan Smith]

I'd use a one-piece top if I could find one.
No pesky joint, and no dark side / light side depending how light hits it, and no grain direction switch between the sides, making carving easier.
Dan

[Dave Locher]

That was my thinking, Dan. Thanks for backing me up, I appreciate words of wisdom from more experienced people.

[Bryan Bear]

I think it is largely aesthetic and subjective. I like the look of bookmatched curly maple tops. The mirroring of the light/dark portions looks spiffy IMHO. As you have seen, this is a matter of personal opinion. With quilted maple, I would strongly prefer one piece. Again, very subjective.

[Randolph Rhett]

Finding a 14" wide board is a lot harder than a 7" board. That's one cosideration. Also, not likely to have vertical grain orientation on a 14" board, so would be more suceptible to movement and ambient moisture. Of course I'm assuming you will be glueing it to a mahogany body. That will probably cancel any tendency for splitting or checking on a 14" wide riff sawn board.

[Dave Locher]

Can you explain the vertical grain thing, and any other technical stuff I should know before I buy an expensive hunk of wood?
I understand flat-sawn vs. quarter sawn, and the different types of maple, but that's about the extent of my knowledge in this area. I don't even know what riff sawn means or if it's good or bad in this context.

[Randolph Rhett]

"Quartered sawn" and "Flat Sawn" are actually milling terms, although used a lot to describe a piece of wood. For most purposes "vertical grain" and "quarter sawn" mean the same thing to us buyers of milled wood. We are talking about a pice of wood where if you look at the end grain (in the direction the tree grew) you will see the growth rings of the tree perpendicular to the widest face. Like |||||||||||||. "flat sawn" or "horizontal grain" mean a piece of wood that has the growth rings parallel to the widest face ======. Most wood is milled so that the board is something in between. ///////. Usually referred to as "riff sawn" (maybe spelled "rift", I don't know. Only heard the word, not read it).

Because growth rings are circular, you need a pretty enormous tree to have 14" of growth rings that look like |||||||||||||. If you go to your typical lumber yard you will see that 2x10's or 2x12 often go right through the middle of a tree like this |||||/////(((0)))\\\\\||||||. The problem is that a board with growth rings that look like this ||///// or worse yet //== will expand and contract with time and humidity much more than wood with perfectly parallel grain perpendicular with the widest face like this ||||||||||. Because we luthiers tend to work with pretty flat thin boards prone to warping, cupping, splitting,etc, we tend to demand |||||||||||||||. A picnic table can have cracks and checks and have "character". Usually not a guitar.

You will have less movement in a 7" board than a 14" board, and are more likely to find it mostly |||||||||| and parallel (realistically something like ||||||||//). However, mahogany is particularly stable wood so it helps keep that figured top from splitting or moving. People use ///=== wood all the time without too much trouble as a "drop top" on mahogany. The wider the board, the more it moves. Using a 14" board you will be putting the body wood much more to the test.

So, lots of advantages to a 7" board and few disadvantages other than a center seam. That is probably why factories have used a bookmatched top for decades. To paraphrase Alan Carruth, if luthiers have been doing it the same way for decades there is probably a good reason.

[Dave Locher]

Thank you for that detailed and informative response. I now understand exactly what you mean and I can see how finding one piece that wide with "good" grain all across would be awfully difficult. You are an excellent teacher!
I'm actually planning to use walnut for the slab, although I'm considering poplar. I'm guessing poplar might not be as stable?

[David King]

Dave you can look up the stability of all the woods on the web for comparison.
Page 9 of this document will get you started: http://www.fpl.fs.fed.us/documnts/fplgt ... 3/ch03.pdf
Well seasoned and acclimated wood will probably make more difference than mixing and matching species. It's important to know ahead of time where the guitar will come to reside. If you live on the coast and plan to ship to the mountain desert, say Las Vegas, you need to get your wood very dry and build in a very dry environment. Your choice of finish is also going to play a role in a solid body.

I don't quite understand Randolph's assertion that a wider piece of wood will move more than two smaller pieces glued side by side all else being equal. Wood moves uniformly along a particular grain orientation regardless of the overall dimension.

[Dave Locher]

I think he meant that one could find two 7-inch boards with uniform grain but it would be very hard to find a 14-inch board that does not have a lot of variation in grain direction, which would tend to cause the board to shrink & expand in different ways across the width of the board.
Interesting report, thank you for the link.

[David King]

Just as an aside those shrinkage numbers are for green lumber going to dry. Some woods shrink a great deal but are very stable once dry. Other woods might not shrink so much but will be more susceptible to ambient changes in MC.

[Randolph Rhett]

I don't quite understand Randolph's assertion that a wider piece of wood will move more than two smaller pieces glued side by side all else being equal. Wood moves uniformly along a particular grain orientation regardless of the overall dimension.

Because the wider board you have, the more chance of having varying grain orientation. Even if one side is |||| chances on a larger board the other side will be /// at best. Two book matched narrower boards will more likely have the same orientation across the width. All things being equal this: ||||||||/////// board will move more than two like this |||||||:|||||||