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BobN
03-11-2011, 02:58 PM
I have built a couple of classical guitars, a tenor and a concert uke and a few mongrel and experimental instruments.

I have some plans for a soprano ukulele. There are no braces on the lower bout other than the bridge patch.

How can I build get the top to keep a dome? or do they have a flat top?

Allen
03-11-2011, 08:22 PM
This should be easy for you then. Your bridge patch is going to take care of that for you. A soprano soundboard is pretty darn small so it's not going to look like much of a radius.

Couple of options on how to do it. Use a radius dish to press in a bridge patch. Or dry your sound board out more than what the RH normally is prior to installing the bridge patch. You could do this with a hair drier or heat gun. Sit it under a heat lamp, or even put it in an oven at a very low temp.

When you glue on the bridge patch to the over dry sound board it will lock the two parts together, and when the moisture content returns to normal for the soundboard the inside will not be able to move, while the outside will. Thus bending the top.

Don't do this with the transverse braces on either side of the sound hole as you want those areas to stay flat.

You can also sand a radius onto your sides as is standard in steel string guitars to help with putting and holding that radius in the top if your building style permits that. I build with a Spanish heel so this isn't an option for me. But if you've done classical guitars you'll be familiar with the options available.

BobN
03-12-2011, 02:13 PM
Thank Allen,
That makes sense. The bridge patch glued in using a go-bar deck with the top in a radius dish (solera). That is what I plan to do.

Vic D
03-12-2011, 03:18 PM
Keep us posted Bob. BTW, I go a little thick on my bridge patches and then sand a bit of the radius (22' for my soprano tops) into them before gluing them up. Might be something to consider, I dunno, I have freaky ideas. Domed is the way to go.