I have been intrigued with this shortcut, which you may find of interest. Cones have several uses, such as sheet-metal chimney caps, but the layout of a cone is puzzling to some craftsmen. Here is a fast method that doesn’t require higher mathematics. The example shows how to lay out a cone 6 in. high with a 24-in. dia. base.
Using the slant length as radius, scribe a circle on the material, and snip. Then measure the base circumference of the cone on the circle, adding at least a 3/4-in. overlap for screws, and cut out the wedge.
—William A. Julien, S. Chatham, MA
Edited and illustrated by Charles Miller
From Fine Homebuilding #4