Mechanical Pencil

FAUL . Faculdade de Arquitectura da Universidade de Lisboa | 2014 | 2nd Semester | Inglês Técnico Adriana Brazão . 7306

MECHANICAL PENCIL T e chn ical Diction ary

Introdução

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Introduction

Breve história da lapiseira

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A Brief History of the Mechanical Pencil

vantagens

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Advantages

Contrução e interiores

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Construction and Internals

Caracteristicas

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Features

Tipos de mecanismo

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Mechanism Types

LAPISEIRA

Sinónimos: porta-minas, porta-lápis, grafite.

Substantivo feminino Utensílio de escrita ou desenho composto por um tubo onde se introduz uma ponta de lápis ou um pau de grafite.

MECHANICAL PENCIL

Synonyms:(UK) propelling pencil, (Australian) pacer, (Indian English) pen pencil Noun A pencil with a replaceable and mechanically extendable lead that wears away with use, designed to provide lines of constant thickness without requiring sharpening and typically features a small eraser at the end opposite the tip.

Introduction A mechanical pencil is a pencil with a replaceable and mechanically extendable solid pigment core called a lead. The lead is not bonded to the outer casing and can be extended as its point is worn away. The lead is actually made of graphite or a solid pigment.

Mechanical pencils were first used in the 18th century with many designs patented in the 19th and 20th centuries and are used to provide lines of constant thickness without sharpening in technical drawing and writing.

The very first pencils were in some ways closer to mechanical pencils than to what we think of now as ‘ordinary’ wood-cased pencils. Pieces of graphite were put in a holder of some sort (often made of wood), to avoid making a mess of peoples’ fingers, and to make writing and drawing more comfortable. The first patent for a mechanical pencil was in Britain, in the early 19th century, but improvements have been made all over the world since then.

Modern thin-lead mechanical pencils were made possible through advances in lead composition, mainly pioneered in Japan. The lead in wood-cased pencils is a mixture of graphite and clay, but this is too brittle for 0.5mm leads, and even 0.9mm leads snap too easily. Modern leads are based on carbon made from high polymer organic materials, and can take a little more force and flexing without snapping.

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1 | Oldest pencil in the world.

A Brief History of the Mechanical Pencil

Conrad Gesner described a leadholder pencil in 1565, but the lead had to be manually adjusted to sharpen it. The earliest extant 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 and John Isaac Hawkins in Britain 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.[10][11] After 1837, Sampson Mordan ended the 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, 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-loaded mechanical pencil was patented in 1877 and a twist-feed mechanism was developed in 1895. The 0.9 mm lead was introduced in 1938, and later it was followed by 0.3, 0.5 and 0.7. Even 1.3 and 1.4 mm mechanisms were available, and 0.4 and 0.2 versions are now produced.

The mechanical pencil became successful in Japan with some improvements in 1915 by Tokuji Hayakawa, a metal worker who had just finished his apprenticeship. 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 Tokyo and Osaka made large orders. Later Tokuji Hayakawa’s company got its name from that pencil: Sharp.

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.

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ADVANTAGES

We’re not against the wood-cased pencil and there are many situations where a wood-cased pencil is a better tool, not least because it’s capable of much more expression and can make a wider range of marks. It’s also a simpler and more dependable tool, and can be found in a greater variety of hardnesses.

No need to sharpen!

With thin enough lead, you don't need to sharpen your pencil, because the line will never be too thick.

Consistent line: especially important for engineering and technical drawings, if a mechanical pencil is held upright, the line width will stay exactly the same. If you need a 0.5mm line, a mechanical pencil can provide it predictably, a wood-cased pencil can't.

Balance!

Many artists use mechanical pencils for this reason. With a wood-cased pencil, as it's used and sharpened, it gets shorter and shorter, and the balance of the pencil changes. Eventually, it becomes too short to use comfortably, and is thrown away.

Refillable: rather than being used up and disposed of, the pencil can have more leads poured into the top. The same pencil can usually be used for many years, depending on the quality.

2 | Several XVII Century’s Mechanical Pencils made in gold and copper.

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Construction and Internals

3 and 4 | Diagram from Staedtler, showing the internal mechanism of a Mars Micro pencil.

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FEATURES The secret of moving the lead forward is in the clamping chuck and chuck ring.

When the button is pushed, the clamping chuck is pushed downwards, and slides the chuck ring along with it. Because it is held closed on the lead, it also pushes the lead down by one ‘click’. When the chuck ring can’t move any further, the clamping chuck carries on, and is allowed to open up a bit, releasing its grip on the lead.

At this point, you release the button again, letting the spring pull the clamping chuck back upwards. It pushes the chuck ring ahead of it, but the lead is now held in place by the lead retainer, and the clamping chuck is spread open, not gripping the lead. So, the lead stays where it is. Because the lead retainer only grips the lead fairly loosely, when the button is pushed in, you can ‘manually’ push the spare lead back up into the pencil.

As the button returns to its usual ‘home’ position, the clamping chuck pulls itself back inside the chuck ring, getting a good grip on the lead again, and keeping it firmly in place for writing and drawing.

L ea d Si z e

5 | Four different lead sizes

For drawing and sketching, you may want quite thick lead, and some mechanical pencils are available with 4mm or thicker lead. For writing, many people prefer 0.9mm or 0.7mm, with 0.5mm and 0.3mm becoming more popular for writing and drawing, and certainly leading the way for technical drawing. The thicker the lead, the more likely it is to need sharpening, but the thicker the line you can get from it, and the easier it is to shade large areas. If you like especially soft or hard lead grades, you may be limited by the thicknesses your preferred grade of lead is available in. 0.5mm usually has the widest choice, and softer grades are more common in thicker leads. If you write or draw ‘aggressively’, thinner leads can be prone to snapping, so you may prefer something thicker and stronger. Modern leads are tougher than older leads, though, so if you used to find 0.5mm leads snapped for you years ago, it might be worth another try with a modern lead like Pentel’s AIN.

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L e a d S le e v e The part that surrounds the lead, just behind the writing tip. Either thin and round or conical. Thin round sleeves are used in drafting pencils. They give an easier view of the drawing area, and allow the pencil to be used more accurately and easily with rules and templates. Sometimes, the sleeve can slide back, so it gets pushed out of the way by the paper if you run low on lead. If you use rules and templates a lot, you may prefer a fixed sleeve, but otherwise, a sliding sleeve can be convenient.

Pencils for writing usually have a conical sleeve, which is less prone to getting bent or broken, and less likely to poke through pockets and accidentally stab your own leg!

R e t ra ctab l e Tip Often referred to as “Pocket Safe”. If you are going to carry a pencil in your pocket, being able to retract the tip part inside the pencil can save your pocket and your leg from damage. This is less important with conical sleeves than with thin sleeves.

L e a d G ra d e In d i c ator Some pencils have an indicator you can set to show which grade of lead you have loaded in that pencil. If you use a number of different pencils, with different hardnesses of leads, this could be very useful. The indicator will usually only have a limited range of hardnesses listed, so if you use unusually hard or soft leads, you may not be covered by all pencils.

G rip You need to be able to hold the pencil comfortably and without it slipping in your fingers, so you need to get a grip that suits your fingers. Many people now like rubber grips, and they are fast becoming the most common type available. Some people still prefer the old-fashioned knurled metal style, and such grips do still exist, especially in drafting pencils. If you have trouble holding a thin pencil, you may want to look for one with a wider grip, like the Faber-Castell.

G rip P lus Don’t always assume, though, that rubber will be the most non-slip surface some plastic or metal grips can be very grippy.

T ria ng ula r G r ip s Some people find a triangular grip section more comfortable, and it can give you a bit more contact area with the pencil. See the Faber-Castell Grip range, and Staedtler’s Triplus pencils, for some nice examples.

C lip If you like to carry your pencil(s) in a shirt pocket, a pocket clip may be important to you. Most pencils come with a clip of some sort, and in some cases it can be removed. A clip will also stop the pencil from rolling off the desk when you put it down for a moment.

L e a d A dva n c e All mechanical pencils have some way of moving the lead forward. The most common is a button at the top of the pencil, but there are other options available now.

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Top Bu t ton Still the most common, and many pencils with other mechanisms also have a button on the top.

Si d e B u t ton A few pencils are available with a button on the side as well as or instead of the top. This lets you advance the lead without moving the pencil as much, usually using your thumb.

Twi s t Many old models of mechanical pencil used a continuous twist-to-advance mechanism, and there are still a few around. There are also a few models now that ‘click’ forward with a twist - they twist one direction to move the lead forwards, but twist back on a spring - like a cross between a twist and a button-click. This is most often seen in pencil versions of twist action ballpoints.

Shake Where the lead is advanced by shaking the whole pencil up and down. A weight inside the pencil does the work of knocking forward another ‘click’ of lead with each shake. In Pilot’s ‘The Shaker’ range, the weight is in the form of a metal spring wrapped around the lead tube.

E r a s er s Not all mechanical pencils have an eraser, but most do. In the majority of cases, it’s quite small, and just push-fit into the top, often under a cap. Some pencils go one better, and have an eraser that can be advanced and retracted by twisting the top of the pencil, making the eraser last much longer. If you expect to use the eraser, check that you can get refills - for any pencil we sell, we will supply refills if they are available from the manufacturer.

Spec ia l I n te r e s t Fe atu r e s Sma l l Si ze You can get pencils that are just shorter, or shorter and thinner than a normal pencil, useful for keeping in a diary or notebook with a very narrow pen loop.

Fit O r gan ize r Loop Similar to small size, but a bit more specific. If you want to use a pencil in an organizer, like a Filofax, and you want it to fit inside the loop, you may need a fairly narrow pencil.

C u shi on e d Le ad Pencils designed for writing sometimes have a small amount of ‘springiness’ to the lead, to absorb the impact of writing. This can help avoid breaking the lead, and may be especially useful if you tend to write ‘aggressively’ or you could try switching to decaf.

Au to Ad van c e Some pencils, such as the Faber-Castell Grip-matic, advance the lead slowly as you are writing or drawing, which should alleviate the need to keep pausing to ‘click’ more lead out as it gets used up.

Cap Very few mechanical pencils have a cap. It takes longer to open and close it, but in return you get a completely pocket-safe pencil, and you can use it with or without the cap on the back for different balance.

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MECHANISM TYPES

Mechanical pencils can be divided into two basic types: those that both hold the lead and actively propel it forward during use, and those that only hold the lead in position against gravity.

Ratchet-based 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, prevents the lead from either falling freely outward or riding back up into the barrel until the jaws recover their grip.

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. 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. The nib is a spring-loaded collar that, when depressed as the lead is worn away, pulls out more when pressure is released. A very modern type has a mechanical engine that twists the pencil lead 6 degrees counter clockwise every time the lead is pressed on to the paper to keep the lead 50% less broad than the common propelling mechanical pencils, resulting in uniform thickness of the lines written onto the paper. It was first developed by Mitsubishi Pencil Co.,LTD, and named Kuru Toga. Screw-based pencils advance the lead by twisting a screw, which moves a slider down the barrel of the pencil. This was the most common type in the earlier part of the twentieth century. Many of these have a locking mechanism one way to allow the lead to be pushed back into the pencil.

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A clutch pencil or leadholder tends to use thicker leads and generally holds only one piece of lead at a time.

A typical clutch pencil is activated by pressing the eraser cap to open the jaws inside the tip, allowing the lead to freely drop through from the barrel or into it when retracting. Because the lead falls freely when the jaws are opened, its forward movement cannot be controlled except by externally halting its progress. 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 are not normally considered to be in the same category as most pencils with propellant mechanisms.

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