Needing a drawing tool for very large arcs, I figured out a way to make a beam compass from two common compasses and a yardstick. After attaching the drawing compass in rough position, you can adjust its pencil leg to fine-tune the size of the arc. Clamp the compasses to a longer stick, and there is no limit on size.
—WAYNE RALLEY, Phoenix, Ariz.
Illustrations by Dan Thornton
From Fine Woodworking issue #298