Most guitar tops have a radius. Even a “flat top” guitar isn’t really flat. The bottom of the bridge needs to match the tops radius.
This bridge is almost ready to be glued on to the top of this guitar. Before it can be glued there are a few things that need to be prepped.
To do this a I use a sanding board that has the same radius as the top.
This way the bridge can be sanded to match the top.
After any old glue has been removed the bridge is re-glued with fresh hot hide glue.