Pencil sharpener

A pencil sharpener (also referred to as pencil parer) is a device for sharpening a pencil's point by shaving one end. Pencil sharpeners exist in both electric and hand-powered forms.

History

Pencils were in use before the development of devices specifically to sharpen them. Previously, they were sharpened by shaving with a knife. Pencil sharpeners made this task much easier and gave a more uniform result. Some specialized types, such as a Carpenter's Pencil are still usually sharpened with a knife, due to their flat shape, though recently a fixed-blade device with a rotatable collar has become available.

Bernard Lassimone, a French mathematician, applied for the first patent (French patent #2444) on pencil sharpeners in 1828. In 1847, Therry des Estwaux invented the manual pencil sharpener. Electric pencil sharpeners for offices have been made since at least 1917. [See photo at the [http://www.earlyofficemuseum.com/electric_sharpener_gallery.htm Early Office Museum] , which also shows earlier electric sharpeners used industrially.]

They now come in a wide array of colors and shapes. Now, it is common for traditional sharpeners to have a case around them so that the shavings do not fall; you can then remove this and empty the case.

Mechanical sharpeners

A mechanical pencil sharpener is hand-powered.A common, portable variety is usually small and in the shape of a rectangular prism, about 1 x 5/8 x 7/16 inch (2.5 x 1.7 x 1.1 cm) in size with a conical hole on the small end. A sharp blade is mounted in a recess on the largest side such that its sharp edge just enters the cone. The body of the sharpener is often variously countoured, ridged and grooved to make it easier to grip firmly. It has no moving parts. The tip of the pencil is inserted into the hole of the sharpener and twisted, while holding the sharpener motionless. The blade inside the sharpener shaves the wood of the pencil, thus sharpening the tip, while the shavings emerge through a slot along the blade edge. An important feature is a larger clearance hole at the end of the cone allowing sections of the pencil lead which breaks away to be removed with only minor inconvenience. Such sharpeners can be bare or enclosed in a container to collect the shavings. Enclosed sharpeners can be harder to clear in the event of a blockage. The base of such a sharpener is often made of aluminium, magnesium or hard plastic.

A larger, stationary mechanical sharpener can be mounted on a desk or wall and powered by a crank. The pencil is inserted into the sharpener with one hand and the crank is turned with the other. This rotates a set of cylindrical burrs in the mechanism, set at an angle to each other; this quickly sharpens the pencil, with a more precise finish than the simpler blade device. Some such rotary sharpeners have only one burr cylinder. The casing of the sharpener is a repository for the pencil shavings; it needs to be emptied periodically. This type of mechanism was long the standard in offices, schools, and libraries before electric sharpeners became common, and these sturdy devices are still found, however many found in schools are not quite up to par, causing much aggravation.

Electric sharpeners

Electric pencil sharpeners work on the same principle as mechanical ones, but the cylindrical cutter is (or cutters are) rotated rapidly by an electric motor. [ [http://www.officemuseum.com/electric_sharpener_gallery.htm Electric Pencil Sharpeners ] ] Some electric pencil sharpeners are powered by batteries, rather than being plugged into a building's electrical system, making them more portable.

Specialized pencil sharpeners

Specialized sharpeners are available that operate on non-standard sizes of pencil, such as large art pencils used in primary schools. Sharpeners that have two holes, one for normal pencils and one for larger art pencils are still fairly common. Some mechanical sharpeners have a large hole with a rotating disk in front of it that has several holes of different sizes.

Sharpeners of similar design for use on wax crayons are also available, and often included in boxes of crayonsFact|date=March 2008. These often have plastic blades for the softer wax.

Carpenters still use flat pencils, originally intended to give a thicker and stronger lead, but with the same line width. These were traditionally sharpened with tools conveniently to hand, such as planes or sandpaper. Rotating pencil sharpeners are now available for these too, where a rotating plastic collar hold the pencil in position. These work poorly, as the conical point they generate removes all the advantages of the pencil's specialised shape.

Since mechanical pencils dispense the graphite stick progressively as it is used, they do not require sharpening and are usually made of some unsharpenable material such as plastic or metal. Such pencils are sometimes called "self-sharpening pencils." However, prolonged writing periods often cause one side of the graphite to become lopsided and dull. Specialized versions of "pencil sharpener", known as graphite pointers are available for drafters or other mechanical pencil users that demand constantly sharp points Fact|date=March 2008.

There exist knives designed for pencil-sharpening, though they are used rarely in the United StatesFact|date=March 2008. They resemble narrow razor blades.

To add a touch of luxury to an otherwise mundane product, some makers have even offered them gold-plated. [cite web
url=http://www.swatiproducts.com/exclusive_products.htm
title=Gold-plated pencil sharpeners]

External links

* [http://www.officemuseum.com/pencil_sharpeners.htm Antique Pencil Sharpeners]
* [http://www.lolomolubdo.com/ Collector of pencil sharpener]