I'm in the midst of making an Arts and Crafts style sofa (from one of the Shop Drawings for Craftsman Furniture books by Robert Lang) and I'm thinking about how to attach the top. The design is post and frame and panel construction topped off with a ~8" wide U-shaped cap that covers the arms and back.
The cap will be the only thing that's easy to grab when the sofa is moved so it will have to be well attached to the frame.
The sketch shows one post and part of the frame. The cap will sit on the posts, the top edge of the rails, and 7 corbels. The two corner joints of the cap itself will be mitered and joined with dowels and glue. The rails will provide the only long-grain glue surface between the frame and the cap. There will be about a 10:1 lever arm working on the effective gluing area when the sofa is lifted by the edge of the top cap, so I'm thinking that something in addition to the long grain glue joint will be needed.
I'm considering:
1) Dowels to connect the corbels and top cap
or
2) Screws angled upward through the corbels into the underside of the top cap.
Your thoughts?