Round and Vaulted Tops
The function of the tools I use and how they work are explained here. Specific tools used are noted in bold.
The arched and vaulted top door top rails (horizontal pieces) are more complicated given that they need to be made from multiple pieces. This is compared to the rectangle and arched top rails which can be made from a single piece of wood.
The traditional construction approach is the make the rails out of 2-3 pieces of solid wood and “butt” joint the ends together. This is problematic in that the butt joint is inherently weak, and at the end of the pieces there is wood grain running more perpendicular to edge of rails. This “short” grain has far less strength and is prone to break.
The approach I use is to laminate the rails out of three plies. The pieces are connected similar to bricks, where one joint is lapped by the middle of another piece(s). This results in a much stronger joint, and any short grain is strengthened by its mating pieces’ long grain.
To make the plies the boards are resawn (cut parallel to the face) on the bandsaw. The plies are then sanded to a consistent thickness in the thickness sander. Wooden templates are made to match the arch and vault. The bandsaw is used to cut out the curved pieces. The pieces are end glued with epoxy to form each layer.
he pieces are end-glued together with epoxy to form each layer. The layers are then trimmed and laminated together with more epoxy. The laminated pieces are put into the vacuum press. When the air is pumped from the bag, atmospheric pressure clamps the pieces together while the glue dries.
In addition to the round top and vaulted top rails, the rails and stiles for the vaulted door are also laminated from three plies. This is because I didn’t have two matching pieces of thick mahogany. As the finish on this door is clear varnish, the different wood grain and color would be obvious. By building the pieces from plies, matching plies from the same board can be used on the outside of the rails and stiles, thus ensuring that everything visually matches.