This is eye opening....your craftsmanship is amazing...beautiful.
Sorry for my ignorant, may I know what is the purpose of these two holes at both side there?
Those are additional sound holes. Much has been written here about them; if you use the search function with key words 'sound ports' or 'ports' you will find plenty of posts discussing them.
Jim Kirby wrote:Stunning!
I note with interest your kerfed bridge caul, intended to allow the caul to follow the existing dome. I always find that I lose some of the intended dome after gluing in the fans, and have taken to using a solid caul contoured to follow the intended dome, in order to get it back. I feel like I'm doing something wrong in the first place. How to you get the initial top dome to stay put? (Question to anyone, really).
Two things come to mind right off-keep the top lightly clamped on your solera/workboard during the entire process of bracing. When you are done with the top, glue it on the body right away. If you're not ready, then keep it clamped to the solera until you are. You have to time this. The other thing is to keep a close eye on the humidity in your shop. You will want to glue the top on the body with the humidity at the same level as it was when you braced it. Even with this you may find you will lose a little height to your dome. If your bridge is shaped properly, relative to the dishing of your solera, then it will pull the top back into that shape. You should only have to use minimal clamping pressure with the bridge. If you are closing a huge gap by clamping then something else is going on. Hope this helps.
Just thought of something else. The bracing stock might not be stiff enough, or overly stiff, to hold the shape. This is actually pretty important in my book-you have to balance the dimensional factor of the bracing relative to your final top thickness and the finished stiffness of the bracing. The bracing is coaxing the top into a particular shape, so top and bracing have to work together to maintain it. It's a type of half torsion box-there's no second 'skin' to help maintain the shape, so the balance has to be right.