Drilling a Pentagonal Hole
Drilling a Pentagonal Hole
The construction shown lets you turn circular motion into pentagonal motion and so construct a drill that drills pentagonal holes. The roller—the yellow shape that rotates within the large pentagon—consists of six circular arcs. As it rotates, the two centers of the smaller circles trace out an exact regular pentagon. You can vary the size of the roller so as to get pentagonal holes of different sizes without changing the ambient pentagon.