Semi hollow design question

[igowing]

I'm currently working on plans for building my second electric mando, and I have run into question I cannot answer. I plan to build a flat-top semi hollow with a koa soundboard, back, and sides. I'm using a neck through design with a maple neck. The center block will run the length of the body My question is that with the soundboard and back mounted on the center block, is any sort of bracing necessary? Will adding bracing help tone or sustain at all? Do other semi-hollow emando's use bracing? Thanks all.

[mandroid]

I think the load of the bridge is passing directly to the block under the top if its glued to it.

routing out the wings on a otherwise solid body instrument with a nice piece of figured wood on the top would be a looker.

I had a 4 string made.. Alder body's face was arched, after, cavities were cut out from the back,[a drill press used],
leaving a solid strip down the middle, then the back was added.
I provided a piece of Baltic all birch plywood for the back,
and that is the whole back ,
{its an A pear-shaped body}, rather than small panels behind the pots and such.

a figured veneer on the back seemed superfluous , but that could be added, of course..

[Cliff D]

May I suggest you take a look at some semi hollow guitars & see what has been done there. As far as I'm aware my Epiphone has no internal bracing & the thru neck runs to the far belt stud, but I've not ripped it apart to see! As Mandroid points out, if the top is glued in place & the strings are anchored at the tail end to the same piece of wood that is the neck there seems little structural reason for bracing.

I think bracing tends to inhibit table vibration & there is always a compromise between physical strength & acoustic properties in fully hollow instruments, but I don't have any real expertise to share in this department (although I know there are cafe members who do!).

[TomMorici]

A few factors will fall into play,how thick will the top be,
and what type of bridge do you plan on using?

I build semi-hollow mandolins and I have also built a couple
of semi-hollow electric guitars. I have never found a need to
add additional top braces. It won't hurt if you do want to add bracing.

I agree that a neck thru design adds the support needed for the bridge. You could always glue a couple of blocks to the side of your neck shaft to widen the area at the bridge.

I hope this helps. Feel free to ask if you have more ???s

Tom