Top and Back

Most tops and backs are book-matched (re-sawn from the same board and opened like the pages of a book). Some builders of smaller instruments use a single piece, but I like the symmetry of a book-matched top or back—particularly when the grain has a nice pattern.

Spruce has been the traditional wood of choice for guitar-family instruments, but ukuleles are an exception. Mahogany was used for the entire instrument in Martin ukuleles (I've still got a Martin soprano ukulele I got when I was eleven or twelve years old). Ukuleles made in Hawaii have tended to use koa, a wood similar to mahogany, but with sometimes striking grain patterns. Many other woods may be used, but tops are usually softwood, while the back and sides are usually hardwood.

My first hand-made uke was made mostly from wood available at my local Home Depot. I chose hemlock for the top (Home Depot doesn't carry spruce, but hemlock is a somewhat similar evergreen softwood). The back, sides and neck were of poplar. Home Depot offered no other hardwood except oak, which looks good in furniture and cabinets, but is not really suitable for musical instruments.

I needed a hardwood for the fretboard. Traditional woods are ebony or rosewood, neither of which was available at Home Depot. I raided my firewood pile for a piece of locally grown black locust.

Two sets of bookmatched koa (for tops or backs)

After the wood for the top has been cut into properly book matched pieces, it is planed and sanded to a little thicker than its final thickness. The edges that will be joined together are carefully trimmed so that they join perfectly, with no gaps. Then the two pieces are glued together. The traditional glue for stringed instruments is animal hide glue. Some builders still use if, but more (including me) use a carpenters' glue such as Titebond.

After the glue dries, the new piece can be lightly sanded to "true up" the glue joint. Then the center of the sound hole is marked and a pilot hole is drilled. The pilot hole is placed over an indexing pin in a workboard I use for routing the groove that will later receive the rosette.

Koa top with rosette in place

Rosettes serve a dual function: they are decorative, and they also reinforce the sound hole to prevent splitting. I make mine from thin acrylic bordered with plastic strips called purfling. The rosette is shaped to fit the slot as exactly as possible—and it's just slightly thicker than the depth of the groove that was routed earlier. After the rosette is glued in place it can be sanded flush with the top's surface.

Carving the top braces

The next step is to turn the top over and glue the braces in place. There are two transverse braces—one above and one below the sound hole. The lower bout has a patch or "graft" of thin reinforcing wood in the area that will support the bridge. Three "fan" braces help prevent warping that might happen as a result of the string tension on the bridge. The braces have to be strong while being as light as possible. The grain in the wood needs to run vertically for strength.

Back with braces and center graft

The back is made very much like the top, except that it has no sound hole and the bracing scheme is different. The back has three transverse braces which (unlike the top braces) have a slight arch. There's also a patch (graft) of cross-grained wood that covers the center seam.