Editing Pencil sharpener (section)

==Manual sharpeners==

=== Prism sharpeners ===
{{original research|section|date=October 2024}}
[[File:KUM Sharpener.jpg|thumb|[[Magnesium alloy]] prism sharpener]]
So-called "prism" sharpeners, also called "manual" or "pocket" sharpeners in the United States, have no separate moving parts and are typically the smallest and cheapest commonly used pencil sharpener on the market. The simplest common variety is a small rectangular [[prism (geometry)|prism]] or block, only about 1 × 5/8 × 7/16&nbsp;inch (2.5 × 1.7 × 1.1&nbsp;cm) in size. The block-shaped sharpener consists of a combined point-shaping cone that is aligned to the cylindrical pencil alignment guide hole, into which the pencil is inserted. A sharp blade is mounted so that its sharp edge just enters the shaping cone [[tangent]]ially. The pencil is inserted into the sharpener and rotated while the sharpener is held motionless. The body of the sharpener is often contoured, ridged or grooved to make the small block easier to firmly grip, and is typically made of [[aluminum alloy]], [[magnesium alloy]] or hard [[plastic]].

[[File:Taille crayon mécanique-h.jpg|thumb|upright|An unusual hand-cranked prism sharpener, with a shavings cover]]
The blade inside the sharpener shaves the wood and graphite tip of the pencil, while the shavings emerge through a slot along the blade edge. It is important that the cylindrical alignment hole closely fits the diameter of the pencil, to keep the pencil from wobbling, which would cause stepped or lurching cut-depths and point breakage. Another important feature is a larger clearance hole at the end of the cone allowing sections of the pencil lead which break away to be removed with only minor inconvenience. Prism sharpeners can be bare or enclosed in a container to collect the shavings, while some enclosed sharpeners may be harder to clear in the event of a blockage.

A few prism sharpeners are hand-cranked, rotating the cutting blade instead of rotating the pencil. Moderate care is needed to not break the tip of the pencil being sharpened, requiring the pencil to be sharpened again. However, because pencils may have different standard diameters in different nations, imported sharpeners may have non-standard-sized alignment guide-holes, making sharpening attempts difficult. If the alignment hole is too small, the pencil cannot be inserted, while if it is too large, the tip of the pencil will repeatedly break off. Prism sharpeners may be right- or left-handed, requiring clockwise or counter-clockwise rotation of the pencil being sharpened.

=== Linear blade sharpeners ===
[[File:Temperowka.na.zyletke.jpg|thumb|A linear sharpener that uses a [[razor|razor blade]]]]
Unlike prism sharpeners, linear blade sharpeners do not rotate relative to the pencil being sharpened, and may be viewed as just a special form of knife, with a mechanical guide for increased safety and convenience. Some models use replaceable shaving [[razor blade]]s, while others have permanently-fitted blades. Linear blade sharpeners may require more skill, but they allow one to sharpen the tip of the pencil into any desired shape and angle of taper, whereas prism sharpeners have a fixed sharpening angle and produce circular symmetry.

While most linear blade sharpeners are simple and directly hand-operated, some devices in the past were crank-operated, using mechanisms to convert crank rotation into linear motion.<ref name="officemuseum">{{cite web |url=http://www.officemuseum.com/pencil_sharpeners.htm |title=Pencil Sharpeners|access-date=9 July 2011}}</ref>

=== 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}}

=== Other systems ===
[[File:BleistiftschärfMaschineJupiter1.JPG|thumb|Jupiter 1 with rotary disk cutters]]
Some older models like the 1897 German Jupiter 1 used reversible rotary cutter-disks with cutting edges radiating from the center on each side. These were high-end models, quite large and expensive. Others simply used abrasives like [[sandpaper]]. In some cases an abrasive was used to shape the graphite core, while the wood was cut some other way.{{Citation needed|date=March 2018}}