Precision Circle Cutting Jig

Cutting a perfect circle freehand is just about impossible. You'll get much better results using a classic jig that allows you to rotate the workpiece on a nail or dowel—a "pivot pin." There's a new twist on this jig: The pivot pin is housed in a sliding runner. To make a circle of any radius, you simply adjust the runner's position. This video shows how the jig works and all the steps in building one.