How to Cut an Arch for a Door in Inch Wood

Place a 4-by-8-foot sheet of 1-inch-thick plywood on sawhorses. Position a sheet of 4-by-8-foot craft paper on top of the plywood. Tape the paper to the plywood. By using the maximum standard size sheet of plywood, you will have as much room for your arch as possible. Measure the width of the door. Mark the width along the long edge of the plywood, staying at least four inches from the side edge to make cutting easier. Label the left-side width mark "A," and the right-side width mark "B." Divide the measurement in half and mark the center point of the width. Label the center mark "C."

Draw a vertical line up from "C" to the top of the craft paper and the plywood, using a pencil and a straightedge. This is the maximum height of the arch you can cut from this size plywood. For a palladium-style arch that is the width of the door, place a push pin on your center mark. Attach a string to the pin. Extend the string horizontally to "A."

Tie a pencil to the string so that the lead of the pencil is over the "A" when the pencil is straight up and down. Keep the pencil straight and rotate the pencil, keeping the string taut. Draw a half-circle arch.

Cut out your full or half outline and trace your arch onto the plywood. You use the craft paper to test out different arch shapes instead of cutting the plywood and making a mistake. Cut the arch using a jigsaw with new, longer blades. Allow the saw to do the cutting as you follow your outline.