Official Luthiers Forum!

Hey all,
I just got asked to build an uke for a good friend and client in Malorca, Spain. Best part is, my daughter is taking a senior trip over there in July and can take it to him. Worst part is, it needs to be done before my daughter leaves for Spain.

So, any help,here will be appreciated as I’m a noob when it comes to Ukes.

First question, to book match, or not to book match?
The koa I have ( bought when I was on a school trip in Hawaii) is big enough that an entire uke top and back can be made in one piece. Is there any reason, other than aesthetics, that the top needs to be book matched?

Next, the only ukes I’ve made had spruce tops. How different should the koa top be braced? ie what considerations need to be made as i go into this uncharted territory?

Finally, is a rosewood fingerboard/bridge going to be an issue for customs?

I’m sure I’ll come up with other questions, but answers to those will get me rollin’

Thanks in advance,
dave

What size? Sopranos are the trickiest to get right.

I'm guessing soprano because one piece koa tops and backs for bigger sizes are very rare. One piece soprano tops and backs were common in the 20s and 30s when large koa boards were available, and some players see them as rather cool on modern builds. Structurally, book-matched works just as well, so it's a matter of aesthetics and perception of cool!

This will be a concert size instrument.

Bracing will be very like a spruce top - I'd guess a cross brace and 2 or 3 fans is what you'd go for.

The main thing to work on is getting the top thin enough. Hardwood tops are usually 2mm or less, sometimes even as thin as 1.5mm (1.5mm = 1/16 inch for conversion purposes).

It all depends on the stiffness of your koa - hardwoods are very variable, here, and koa is more variable than most! All I can suggest is to thin it, flex it, and then be brave and thin it a bit more. If I can deflect the top around 1 inch in it centre, flexing longitudinally with light finger and thumb pressure, then I'm there. Cross grain stiffness can be dealt with by the bracing - I make them all a little over size and then thin down until the top feels ready, which is impossible to describe, but if you've made a few ukes you'll have an idea. A hardwood top will feel more fragile in hand, but will flex and deflect very like a spruce top once braced.

Back and sides equally thin, unless you go for the building model of really solid sides, but I don't think that gives you the traditional uke sound.

Can't help on rosewood import I'm afraid. Walnut makes a decent uke fretboard and bridge.