MIMF

I'm building my first ukulele from scratch. I'm patterning it from an old busted up pineapple soprano uke. This uke has (or had) two transverse back braces, 1 about 3 5/8 from the heel, the other about 7 inches from the heel. The overall body length is 9 3/8" The top also has two transverse braces, one 1 5/8 and the other 4 7/16" from the heel, with the sound hole centered between them. These measurements are to the center of the braces. The back braces are 1/4 x 1/2" cross section, the top are 1/4 x 3/8". There is also a strip of wood glued across the sides about at the halfway mark, and reaching between the top and back linings My question is: Is this adequate bracing for the instrument?

Looking at the several cracks in the body, it seems most are due to the brace glue giving way or the brace itself splitting away, or the top separating from the sides in places. The top is slightly bowed from string tension. Should I run a couple of longitudinal braces from the second transverse brace to the tail block, or would this kill the sound?

Jon, that bracing sounds minimal. There are several sites with pics of various bracing patterns, try Kathy Matsushita's site. Also be wary of the Kasha style "systems". The really good sounding ukes I have seen are built very lightly. You have a lot of ingenuity so I'm sure you will figure out a good design.

That sounds about standard for a soprano pineapple. The longitudinal braces would definitely kill the sound.

Cracks and brace joint failure sounds like humidity swings, not under bracing. I'd probably brace a little lighter on the back.

This is fairly typical bracing for a soprano uke. The brace above the soundhole is flat; the one below is radiused. Likewise I use a radiused caul when gluing the bridge patch to the top.

Rob makes a very nice uke, so copy his work.

I think the final height of braces depends on how stiff the top turns out to be. For a pineapple I'd make the top braces about 1/4 wide and 3/8 high, but almost a triangular section. Then I'd reduce the height until the top felt "right" - no idea how to explain that.

Haven't had one fold up on me yet, but Rob has more experience and you can see that he shapes differently.