The whole rectangular panel is feathered all around first so I have a reference at the top of the arch for shaping and carving. This arch is a half circle, but many are not, whether its on walls, doors, cupboards throughout the colonies, and they all work visually. Carving these arches is time consuming and requires exacting work, all of your depth cuts and mitres must be right, or you start over! The whole process of reproducing authentically the wonderful craftsmanship of our colonial forefathers is a great satisfaction, because, I get to live their process, share in their accomplishments and say, I know what you did here-right here, and know them in this way!!! >