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A mechanical pencil or clutch pencil is a
pencil A pencil () is a writing or drawing implement with a solid pigment core in a protective casing that reduces the risk of core breakage and keeps it from marking the user's hand. Pencils create marks by physical abrasion, leaving a trail of ...
with a replaceable and mechanically extendable solid pigment core called a "lead" . The
lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
, often made of
graphite Graphite () is a Crystallinity, crystalline allotrope (form) of the element carbon. It consists of many stacked Layered materials, layers of graphene, typically in excess of hundreds of layers. Graphite occurs naturally and is the most stable ...
, is not bonded to the outer casing, and the user can mechanically extend it as its point is worn away from use. The vast majority of mechanical pencils have
erasers An eraser (also known as a rubber in some Commonwealth countries, including South Africa from which the material first used got its name) is an article of stationery that is used for removing marks from paper or skin (e.g. parchment or vellu ...
. Other names include: microtip pencil, automatic pencil, drafting pencil, technical pencil, draughting pencil, click pencil (generally refers to a specific brand), pump pencil, leadholder, Pacer (Australian English, ca. the 1980s), propelling pencil (British and Australian English, often refers to higher-end mechanical pencils), pen pencil (Indian English), and lead pencil (Bangladeshi and American English). Mechanical pencils are used to provide lines of constant width, without need of
sharpening Sharpening is the process of creating or refining a blade, the edge joining two non-coplanar faces into a converging apex, thereby creating an edge of appropriate shape on a tool or implement designed for cutting. Improving sharpness is don ...
, for tasks such as
technical drawing Technical drawing, drafting or drawing, is the act and discipline of composing drawings that visually communicate how something functions or is constructed. Technical drawing is essential for communicating ideas in industry and engineering. ...
as well as for clean looking writing. They are also used for fine-art drawing. Since they do not have to be sharpened, they are also popular with students. Mechanical pencils were first used in the 18th century, with many designs patented in the 19th and 20th centuries.


History

Conrad Gessner Conrad Gessner (; ; 26 March 1516 – 13 December 1565) was a Swiss physician, naturalist, bibliographer, and philologist. Born into a poor family in Zürich, Switzerland, his father and teachers quickly realised his talents and supported him t ...
described a lead holder pencil in 1565, but the lead had to be manually advanced and sharpened. Henry Petroski, ''The Pencil:A History of Design and Circumstances'', Random House, 2011 Random House, 2011 The earliest extant datable example of a mechanical pencil was found aboard the wreckage of HMS ''Pandora'', which sank in 1791. The first patent for a refillable pencil with lead-propelling mechanism was issued to
Sampson Mordan Sampson Mordan (c. 1790 – 9 April 1843) was a British silversmith and a co-inventor of the first patented mechanical pencil. During his youth, he was an apprentice of the inventor and locksmith Joseph Bramah, who patented the first elastic ink ...
and
John Isaac Hawkins John Isaac Hawkins (1772–1855) was a British American inventor and civil engineer who twice emigrated to and ultimately died in the United States, American state of New Jersey. Early life Hawkins was born on March 14, 1772 at Taunton, Somerse ...
in
Britain Britain most often refers to: * Great Britain, a large island comprising the countries of England, Scotland and Wales * The United Kingdom of Great Britain and Northern Ireland, a sovereign state in Europe comprising Great Britain and the north-eas ...
in 1822. After buying out Hawkins' patent rights, Mordan entered into a business partnership with Gabriel Riddle from 1823 to 1837. The earliest Mordan pencils are thus hallmarked SMGR. After 1837, Mordan ended his partnership with Riddle and continued to manufacture pencils as "S. Mordan & Co". His company continued to manufacture pencils and a wide range of silver objects until
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, when the factory was bombed. Between 1822 and 1874, more than 160 patents were registered pertaining to a variety of improvements to mechanical pencils. The first
spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of water * Spring (mathematics), a geometric surface in the shape of a he ...
-loaded mechanical pencil was patented in 1877. Two of the most popular 19th-century lead sizes were 1.5 and 1.03 mm, "VS" and "M", respectively. Many other sizes were in use, however, before the Eversharp's success made its .046 inch lead size a de facto standard (this size has been variously metricized as 1.1, 1.18, and 1.2 mm, all nominal sizes). Thinner .036 inch (0.9 mm) lead was introduced in the later 1930s and gradually became the new standard, eventually being displaced by 0.7 mm. Many thinner sizes are now available, as well as thicker leads such as 1.4 and 2.0 mm. The first modern mechanical pencil was the Eversharp (originally "Ever Sharp"), invented by Charles R. Keeran who applied for the key patent in 1913. It has been described as "the first mass-produced mechanical pencil to combine a simple propelling mechanism with large lead capacity and robust, ergonomically sound design ... that redefined the mechanical pencil as a mass-market product, to the extent that "eversharp" came to be widely used as a generic term for a mechanical pencil." More that 12,000,000 Eversharp pencils had been sold by the early 1920s, and its design was widely copied. A pioneering mechanical pencil in
Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
was invented in 1915 by
Tokuji Hayakawa was a Japanese businessman and the founder of Hayakawa Kinzoku Kōgyō (the present-day Sharp Corporation). He invented and patented the “Tokubijō” belt buckle in 1912 (a belt which can fasten without perforating) and invented the "Ever Rea ...
, a metalworker who had just finished his apprenticeship. It was patented in Japan in 1920 and marketed as the "Ever-Ready Sharp Pencil". Although it has been claimed that large numbers were sold, surviving Ever-Ready Sharps are rare. In 1923, the Hayakawa Brothers factory was destroyed in the Great Kantō earthquake. By 1924, Tokuji Hayakawa had turned his attention to the manufacture of radios, but his first invention was immortalized in the name of his new company: Sharp.


Manufacturers

Some present-day manufacturers are:
Pentel is a privately-held Japanese manufacturing company of stationery products. The name comes from one of their first widely known products and is a portmanteau of the English words ''pen'' and ''pastel''. Pentel is also the inventor of non-perma ...
,
Pilot An aircraft pilot or aviator is a person who controls the flight of an aircraft by operating its Aircraft flight control system, directional flight controls. Some other aircrew, aircrew members, such as navigators or flight engineers, are al ...
,
Tombow is a private Japanese manufacturing company of stationery products. The company was founded in 1913 as Messrs "Tombow" and has since grown into an international business. Based in Tokyo with 397 employees. Tombow also has two overseas produc ...
,
Uni-ball (stylized as uniball) and are brands of pens and pencils, made by the of Japan. The brand was introduced in 1979 as a rollerball pen model, then expanding to the rest of Mitsubishi Pencil products. Mitsubishi Pencil Company distributes over ...
and
Zebra Zebras (, ) (subgenus ''Hippotigris'') are African equines with distinctive black-and-white striped coats. There are three living species: Grévy's zebra (''Equus grevyi''), the plains zebra (''E. quagga''), and the mountain zebra (''E. ...
of Japan;
Faber-Castell Faber-Castell AG is a German privately-held multinational corporation, multinational manufacturer of pens, pencils, other office supplies (e.g., staplers, slide rules, erasers, rulers)Faber-Castell InternationalOffice Products and art supplies,Fa ...
,
Lamy Lamy ( /ˈlɑːmi, ˈlæmi/) is a German pen manufacturing company founded in 1930 by Josef Lamy, a former sales representative for Parker Pen. The company acquired the Orthos pen manufacturer to begin production. Lamy offers a variety of ...
,
Rotring Rotring (stylized rOtring) is a manufacturing company, manufacturer of technical drawing tools and writing implements. Established in Germany in 1928 as a fountain pen manufacturer, Rotring went on to be acquired by Newell Brands in 1998. The ...
and
Staedtler Staedtler SE () is a German multinational stationery manufacturing company based in Nuremberg. The firm was founded by J.S. Staedtler (1800–1872) in 1835 and produces a large variety of stationery products, such as writing implements (includin ...
of Germany;
Koh-i-Noor Hardtmuth Koh-i-Noor Hardtmuth a.s. is a Czech manufacturing company of stationery products, based in České Budějovice. Established in 1790, it is one of the oldest stationery companies in the world. With four factories in its country of origin (Česk� ...
of the Czech Republic; Bic of France;
Monami Monami Co., Ltd () is a Korean maker of stationery, printer supplies, office supplies, pens and other writing instruments as well as artist materials.
of
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...
;
PaperMate Paper Mate is a division of Sanford L.P., a Newell Brands company that produces writing instruments. Paper Mate's offices are located in Oak Brook, Illinois, along with those of Newell Rubbermaid's other office products divisions. Its product ...
and Parker of USA; Caran d'Ache of Switzerland and numerous Chinese as well as other Asian and European manufacturers.


Mechanism types

Mechanical pencils can be divided into two basic types: those that both hold the lead and can actively propel it forward, and those that only hold the lead in position.
Screw A screw is an externally helical threaded fastener capable of being tightened or released by a twisting force (torque) to the screw head, head. The most common uses of screws are to hold objects together and there are many forms for a variety ...
-based pencils advance the lead by twisting a screw mechanism, which moves a propelling pin or lead carrier down the barrel of the pencil. Lead is not fed from an internal reservoir, but must be replaced manually, usually from the front. This was the most common type up until the earlier part of the mid-twentieth century. Most have a mechanism that retracts the lead when twisted the other way, but many older designs do not and the lead must be pushed back into the pencil manually. A clutch pencil (or leadholder) tends to use thicker leads (2.0–5.6 mm) and generally holds only one piece of lead at a time. A typical clutch pencil is activated by pressing the eraser cap on the top, to open the jaws inside the tip and allow the lead to freely drop through from the barrel (or back into it when retracting). Because the lead falls out freely when the jaws are opened, its forward movement cannot be controlled except by external means. This can be easily done by keeping the tip of the pencil a few millimeters above a work surface or the palm of one's hand. Some clutch pencils do have mechanisms which incrementally advance the lead, such as the Alvin Tech-Matic leadholder, but these are not normally considered to be in the same category as most pencils with propelling mechanisms.
Ratchet Ratchet may refer to: Devices * Ratchet (device), a mechanical device that allows movement in only one direction * Ratchet effect in sociology and economics * Ratchet, metonymic name for a socket wrench incorporating a ratcheting device * Ratc ...
-based or "repeater" pencils are a variant of the clutch pencil, in which the lead is held in place by two or three small jaws inside a ring at the tip. The jaws are controlled by a button on the end or the side of the pencil. When the button is pushed, the jaws move forward and separate, allowing the lead to advance. When the button is released and the jaws retract, the "lead retainer" (a small rubber device inside the tip) keeps the lead in place, preventing the lead from either falling freely outward or riding back up into the barrel until the jaws recover their grip. Other designs use a precisely-fitted metal sleeve to guide and support the lead, and do not need a rubber retainer. In one type of ratchet-based pencil, shaking the pencil back and forth causes a weight inside the pencil to operate a mechanism in the cap. A button may be present on the top or side of the pencil, to allow the user to advance the lead manually when necessary. Another variation advances the lead automatically. In this design, the lead is advanced by a ratchet but only prevented from going back into the pencil, just held from falling by a small amount of
friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Types of friction include dry, fluid, lubricated, skin, and internal -- an incomplete list. The study of t ...
. The nib is a spring-loaded collar that, when depressed as the lead is worn away, extends out again when pressure is released. An advanced ratchet type has a mechanism that rotates the pencil lead 9 degrees counter-clockwise every time the lead is pressed on to the paper (which counts as one stroke), to distribute wear evenly. This ''auto-rotation'' mechanism keeps the lead 50% narrower than in the common propelling mechanical pencils, resulting in uniform thickness of the lines written onto the paper. The design was first patented by Schmidt of Germany, and later developed by Mitsubishi Pencil Company of Japan, and named ''Kuru Toga'' under the Uni brand.Kurutoga Website
Kuru Toga, which in Japanese, means "spinning to a taper".
This type of pencil is most suited for Asian languages that have multiple strokes per letter or word, where the pencil is frequently lifted off the paper. The mechanism is less suitable for cursive writing used in western scripts. Another recent auto-rotation movement by Uni rotates the lead 18 degrees per stroke (or 20 strokes per complete revolution), which is better suited for western scripts. There exist protection mechanisms that prevent the lead from breaking (within certain limits) when excessive pressure is exerted while writing. A mechanism employed in the ''DelGuard'' system by Zebra of Japan causes the lead sleeve to extend outward when excessive pressure is applied at an angle. When excess vertical pressure is applied on the lead, the lead is automatically retracted inwards. Higher-end mechanical pencils often feature a lead hardness grade indicator and sometimes feature a retractable lead guide pipe. This allows the lead guide pipe to retract back into the pencil body, which will keep it protected in storage and during transit and makes it 'pocket-safe'.


Lead variations

In spite of the name, pencil leads (also called cores) do not contain the toxic chemical element
lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
, but are typically made with graphite and clay, or plastic polymers. The downside of mechanical leads are that they are not as strong as traditional pencils. Wooden pencil lead is bonded to the outer wooden case, therefore providing more lead protection and strength. This changed in 1962, when Pentel launched new mechanical pencils with the diameters of 0.5mm and 0.7mm. These pencils contained a new type of lead formulated with polymers that act as a binder to strengthen the lead. This polymer replaced the clay in mechanical pencil lead and made it easier for manufacturers to produce lead with smaller diameters. Compared to standard pencils, mechanical pencils have a smaller range of marking types, though numerous variations exist. Most mechanical pencils can be refilled, but some inexpensive models are meant to be disposable and are discarded when empty.


Diameter

Mechanical pencil mechanisms use only a single lead diameter. Some pencils, such as the
Pentel is a privately-held Japanese manufacturing company of stationery products. The name comes from one of their first widely known products and is a portmanteau of the English words ''pen'' and ''pastel''. Pentel is also the inventor of non-perma ...
Function 357, place several mechanisms within the same housing, so as to offer a range of thicknesses (in this case three: 0.3, 0.5 and 0.7 mm). 1.00 mm leads also exist, but they are very rare. Different sizes of lead diameters are available to accommodate various preferences and pencil builds, as shown in the table below. The most common lead sizes are 0.5 mm and 0.7 mm, whose line widths provide a favourable balance between precision and strength. Less common lead sizes can range from 0.2 mm up to 5.6 mm.
Pentel is a privately-held Japanese manufacturing company of stationery products. The name comes from one of their first widely known products and is a portmanteau of the English words ''pen'' and ''pastel''. Pentel is also the inventor of non-perma ...
has also previously demonstrated a prototype 0.1 mm pencil. Pencils with sub-millimeter leads can usually hold multiple leads at the same time, reducing the frequency of refills. One exception was the Pentel 350 E, possibly Pentel's first mechanical pencil, which could only hold a single stick of 0.5 mm lead. Refill leads can be bought in small tubes and inserted into the barrel as needed. The bracketed values in inches were found by calculation and rounded to 3 decimal places. The diameters, however, are not exact. The exact diameter is usually slightly larger. The Japanese JIS standard for mechanical pencil leads, states that the actual diameter for "0.5 mm" lead (for example), should range from 0.55 mm to 0.58 mm.


Length

For sub-millimeter diameter leads, the standard length of the cylindrical stick for all grades is 60 mm. However, some manufacturers make leads that are 75 mm long, for selected grades.


Hardness

As with non-mechanical pencils, the leads of mechanical pencils are available in a range of hardness ratings, depending on the user's desired balance between darkness and durability. A commonly-used mechanical pencil lead is identical in density, but not in thickness to a traditional HB (US#2) pencil lead. The hardness depends on the proportion of polymer or resin and graphite in the lead. It is determined by a numerical scale: the higher the number, the harder the lead. Similarly to standard wooden pencils, the lead is distinguished by grading scales. H stands for hardness; as they are typically harder and produce a light gray color. B stands for blackness; they produce a darker color and are typically softer. F stands for fine; it is in between H and HB on the lead grading scale. Compared to standard pencils that have 24 grades of lead, there are only 10 grades of mechanical pencil lead, ranging from 4H-4B.


Pigments

Mechanical pencils with colored leads are less common, but do exist.
Crayola Crayola LLC, formerly the Binney & Smith Company, is an American manufacturing and retail company specializing in list of art media, art supplies. It is known for its brand ''Crayola'' and best known for its crayons. The company is headquartered ...
's "Twistable" product line includes two different types of colored pencils (erasable and non-erasable) with mechanical feed mechanisms that are dispensed by twisting, but does not offer refill leads. Several companies such as
Pentel is a privately-held Japanese manufacturing company of stationery products. The name comes from one of their first widely known products and is a portmanteau of the English words ''pen'' and ''pastel''. Pentel is also the inventor of non-perma ...
,
Pilot An aircraft pilot or aviator is a person who controls the flight of an aircraft by operating its Aircraft flight control system, directional flight controls. Some other aircrew, aircrew members, such as navigators or flight engineers, are al ...
, and
Uni-ball (stylized as uniball) and are brands of pens and pencils, made by the of Japan. The brand was introduced in 1979 as a rollerball pen model, then expanding to the rest of Mitsubishi Pencil products. Mitsubishi Pencil Company distributes over ...
(Mitsubishi Pencil Co.) currently manufacture colored refill leads in a limited range of diameters (0.5 mm, 0.7 mm, or 2.0 mm) for their own products, as well as "variety packs" consisting of different colors of leads for those who want to trial different colors of lead.
Koh-i-Noor The ; ), also spelled Koh-e-Noor, Kohinoor and Koh-i-Nur, is one of the largest cut diamonds in the world, weighing . It is currently set in the Crown of Queen Elizabeth The Queen Mother. The diamond originated in the Kollur mine in present ...
makes mechanical colored pencils with replaceable leads in 2.0, 3.15 and 5.6 mm sizes.Koh-I-Noor 2.0mm leadholders and colour leads
pencil talk. Retrieved on 14 October 2011.


See also

*
Technical drawing tools Drafting tools may be used for measurement and layout of drawings, or to improve the consistency and speed of creation of standard drawing elements. Tools such as pens and pencils mark the drawing medium. Other tools such as straight edges, assist ...


Notes and references


Bibliography

* Deborah Crosby, ''Victorian Pencils: Tools to Jewels'', Schiffer Publishing Ltd., Atglen, PA, 1998 * Jonathan A. Veley, "The Catalogue of American Mechanical Pencils", Greyden Press, 2011


External links


Sharp's history of the mechanical pencil



Leadholder Museum
(History and images of Leadholders)
Sampson Mordan.
First patent for a mechanical pencil

(Bloomington, Illinois newspaper) {{DEFAULTSORT:Mechanical Pencil Pencils Writing implements Mechanisms (engineering)