A ratchet-type mechanical pencil
A mechanical pencil or propelling pencil is a pencil containing an internal mechanism which pushes or propels the thin graphite lead through the tip. A pencil is a Writing or Drawing instrument consisting of a thin stick of Pigment (usually Graphite, but can also be coloured pigment or The Mineral graphite, as with Diamond and Fullerene, is one of the Allotropes of carbon. Like standard pencils, there are also mechanical pencils which have a rubber eraser on the end. An eraser or rubber is an article of Stationery that is used for removing Pencil and sometimes Pen writings Mechanical pencils provide lines of consistent thickness, well suited for technical applications such as drafting and writing.
The mechanical pencil was first invented in Britain in 1822 by Sampson Mordan and Gabriel Riddle. The United Kingdom of Great Britain and Ireland was the formal name of the United Kingdom from 1 January 1801 until 12 April 1927 Earliest Mordan pencils are thus hallmarked SMGR. Sampson Mordan continued manufacturing pencils and a wide range of silver objects until the second world war when their factory was bombed.
Between 1822 to 1874, more than 160 patents were registered pertaining to a variety of improvements to mechanical pencils. The first spring-loaded mechanical pencil was patented in 1877 and a twist-feed mechanism was developed in 1895. A spring is a flexible elastic object used to store mechanical Energy. The 0. 9 mm lead was introduced in 1938, and later it was followed by 0. 7, 0. 5 and 0. 3 mm versions. Even a 1. 4 mm mechanism is available.
Pencil lead for a modern mechanical pencil.
The mechanical pencil became successful in Japan with some improvements in 1915 by Tokuji Hayakawa, a metal worker who had just finished his apprenticeship. For a topic outline on this subject see List of basic Japan topics. It was introduced as the Ever-Ready Sharp Pencil. Success was not immediate, since the metal shaft — essential for the pencil's long life — was unfamiliar to users. The Ever-Sharp began selling in huge numbers, however, after a company from Yokohama made a large order. is the capital of Kanagawa Prefecture, located in the Kantō region of the main island of Honshū and is a major commercial hub of the Greater Tokyo Area Later Tokuji Hayakawa's company got its name from that pencil: Sharp. () is a Japanese Electronics manufacturer founded in 1912 It takes its name from one of its founder's first inventions the Ever-Sharp Mechanical pencil, which
At nearly the same time, in America, Charles R. Keeran was developing a similar pencil that would be the precursor of most of today's pencils. Keeran's design was ratchet-based, whereas Hayakawa's was screw-based. These two development histories are often combined into one.
Metal propelling pencil
A rachet mechanical pencil disassembled, showing three 0. 5 mm graphite leads.
A number of different types exist:
- Ratchet-based pencils, in which the lead is advanced by a button on either the end or the side. In Mechanical engineering, a ratchet is a device that allows linear or rotary motion in only one direction while preventing motion in the opposite direction This button pushes two or three small pieces within the cap forward out of a ring holding them together as one. This separates those pieces, allowing lead to go through between those.
- A variation of the ratchet-based pencil, in which shaking the pencil back and forth causes a weight inside the pencil to operates a mechanism in the cap. A button may be present.
- 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 two Surfaces in contact or a surface in contact with a fluid (e The nib is a spring-loaded collar that, when depressed as the lead is worn away, pulls out more when pressure is next released.
- Screw-based pencils, in which the lead is advanced by twisting a screw, which moves a slider down the barrel of the pencil. A screw is a shaft with a helical groove or thread formed on its surface and provision at one end to turn the screw
- Screw-based pencils in which the lead is advanced by friction with the screw.
- Twist-based pencils, in which the lead advances upon twisting the head of the pencil. Many of these will have a locking mechanism one way to allow the lead to be pushed back into the pencil.
Most mechanical pencils can be refilled with more graphite but some less-expensive models, especially screw-based designs, are disposable.
A Staedtler Mars 780 Leadholder
Clutch pencils (or leadholders) use a thicker solid piece of lead (typically 2–4 mm) and work by pressing down the eraser cap to allow the "claws" at the end to open, which in turn allows the lead to freely drop through the barrel. They can typically only hold one whole piece of lead at a time.
The advantage of clutch pencils is that they allow a greater variety of marks to be made.
The disadvantage is that because the lead falls when the claws are opened, there is no controlled dispersal of the lead and as such it's best done a few millimeters over the work surface.
- ^ History of Leadholders. Société Bic is a company based in Clichy, France, founded in 1945 best known for making Disposable products including Cigarette lighters The Parker Pen Company is a manufacturer of pens founded in 1891 by George Safford Parker in Janesville Wisconsin, United Caran d'Ache is Swiss manufacturer of high-quality Writing instruments fine art products and accessories Faber-Castell is a German manufacturer of writing instruments art supplies staplers and Slide rules founded in 1761 in Nuremberg by Kaspar Koh-I-Noor Hardtmuth as is a Czech manufacturer of a full line of pencils pens art supplies See Lamy (disambiguation for other meanings Lamy (ˈlɑːmɪ is a producer of Fountain pens in Europe. Paper Mate, is a trademark of Sanford LP, a Newell Rubbermaid company is a privately held Japanese company that produces Stationery and Writing instruments. Rotring is a German company based in Hamburg. It was established in 1928 as Tintenkuli Handels GmbH Staedtler Mars GmbH & Co KG is a German fine writing instruments company and one of the world's leading manufacturers and suppliers of writing and Engineering drawing instruments Zebra Pen Corporation is an American manufacturer of high-quality Writing instruments. is a pen manufacturer based in Tokyo, Japan. It produces writing instruments Stationery, and Jewelry but is most well known for Pens. Leadholders. com (2008-01-04). 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 46 BC - Titus Labienus defeats Julius Caesar in the Battle of Ruspina. Retrieved on 2008-02-27. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 1560 - The Treaty of Berwick, which would expel the French from Scotland, is signed by England and the Congregation
© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
- A device, roughly the shape of a pen, into which long thin piece of pencil lead can be placed. A button can then be used to adjust how much of the pencil lead extends beyond the tip of the mechanical pencil, so one can adjust it as the pencil lead wears off through usage. Mechanical pencils usually also have a small eraser at the end opposite the tip.
network: | |