Editing Pencil sharpener (section)

=== Cylindrical (planetary) sharpeners ===
These mechanisms are also called '''planetary sharpeners''',<ref name="officemuseum" /> in reference to their use of [[planetary gear]]s. A larger, stationary planetary sharpener can be mounted on a desk or wall and powered by a hand [[Crank (mechanism)|crank]]. Typically, the pencil is inserted into the sharpener with one hand, and the crank is turned with the other. This rotates a set of [[helix|helical]] cylindrical cutters in the mechanism, set at an acute angle to each other. The multiple cutting edges quickly sharpen the pencil, with a more precise finish than a single-blade device{{Citation needed|date=March 2018}}. Some cylindrical sharpeners have only one helical cutter cylinder{{Citation needed|date=March 2018}}, but most have two cylinders or more.

Most planetary sharpeners have a large opening, with a rotatable guide disk in front of it that has multiple holes of different sizes, to accommodate pencils of many different diameters. Advanced models have a spring-driven holder for the pencil, so that the pencil automatically is pushed into the mechanism while being sharpened. Some versions also offer a regulator of the desired sharpness, since it is not always desired to make the graphite core needle-sharp.{{Citation needed|date=March 2018}}