TECHNICAL DESCRIPTION OF THE MECHANICAL PENCIL 
                          


                                                         TABLE OF THE CONTENTS
Title page ………………………………………………………………………………………. 1

Table of the Contents ……………………………………………………………………. 2

1 Introduction ………………………………………………………………………….……. 3

1.1 Background of The Mechanical Pencil …………………………………..…. 3
1.2 General Description …………………………………………………………………. 3-4

2 Technical Description of The main Parts ……………………………………… 4-12

2.1 The Gripping Assembly …………………………………………………………….. 5-7
2.1.1 The Rubber-Gripping Barrel ………………………………………………….. 5-6

2.1.2 The Cone Cap ……………………………………………………………………..… 6-7
2.1.3 The Lead Rod Outlet ……………………………………………………………… 7

2.2 The Barrel Assembly ………………………………………………………………… 8-11
2.2.1 The Hourglass Barrel …………………………………………………………..… 9
2.2.2 The Pocket Clamp Holder ……………………………………………………… 9-10
2.2.3 The Lead Rod Ejector ………………………………………………………….… 10
2.2.4 The Removable Eraser ………………………………………………………….. 11
2.3 The lead Rods ………………………………………………………………………….. 11-12

3 Conclusion ………………………………………………………………………………..… 12
References ……………………………………………………………………………………. 13


1. Introduction1.1 Background of the mechanical pencil      The mechanical pencil, also known as a propelling pencil or automatic pencil, is a writing instrument that uses a mechanism to extend and retract a lead core as it is used. The earliest known patent for a mechanical pencil was issued in 1822 to Sampson Mordan and John Isaac Hawkins in Great Britain, but it was not until the 20th century that the mechanical pencil became widely popular. In the early 1900s, mechanical pencils were primarily made of metal and were popular among engineers, architects, and draftsmen. They were seen as more convenient and efficient than traditional wooden pencils, which required sharpening and could break easily. In the 1950s and 60s, the popularity of the mechanical pencil continued to grow as more companies began producing them. Some companies, such as Pentel, developed innovative features such as a twist-erase mechanism for erasing and a rotating lead sleeve to reduce breakage. Today, mechanical pencils come in a variety of sizes, colors, and designs, with some models even featuring digital displays for tracking the amount of lead remaining. They remain a popular writing instrument for students, artists, and professionals alike.
1.2 General description
      The Mechanical Pencil is a writing instrument made of durable plastic that can be comfortably held in the hand. A third of the pencil is covered with soft rubber for a comfortable grip while writing or drawing. The bottom of the pencil has a pointed opening where lead can be ejected for writing, while the top has a pocket clamp holder for easy carrying. The eraser at the top can remove lead marks and can be replaced. The internal mechanical assembly, made of aluminum and plastic, is designed to push lead out of the pencil’s bottom.
The mechanical pencil measures 5.5 inches in length and 0.5 inches in diameter.


2. Technical Description of The Main Parts
      The mechanical pencil consists of three main components:
1) The gripping assembly 
2) The barrel assembly 
3) The 0.012” lead Rod 
2.1 The Gripping Assembly 
      The gripping assembly, depicted in Figure 3, is a casing made of rubber and chrome that encloses and protects the internal mechanisms of the mechanical pencil. It also functions as a holder for 0.012-inch lead rods. The rubber casing provides a comfortable finger grip for the user to hold the pencil while writing. The gripping assembly is connected to the barrel assembly of the pencil. It measures 2.5 inches in length and 0.5 inches in diameter.
The gripping assembly consists of three main components:
1) the rubber-gripping barrel
2) the cone cap 
3) the lead rod outlet

2.1.1 The Rubber-Gripping Barrel
      The rubber-gripping barrel depicted in Figure 4 is a component of the mechanical pencil that is used for holding it between the thumb, index finger, and middle finger while writing or drawing. It envelops the hourglass barrel, and has a tapered design in the middle that allows it to securely grip the bottom joint of the middle finger. The ribbed casing enhances the pencil’s grip, and the soft black rubber material is designed for comfortable use even during prolonged periods of writing. It measures 1.75 inches in length and 0.5 inches in diameter.2.1.2 The Cone Cap
      The cone cap, shown in Figure 5, is a casing made of hi-impact plastic that covers the mechanical lead rod holder inside the mechanical pencil. It is also designed to align the 0.012-inch lead rods with the outlet for the lead. The cone cap has a silver chrome finish and is screwed onto the hourglass barrel in a clockwise direction. Its purpose is to protect the internal mechanisms and facilitate the smooth and accurate delivery of lead. It measures 0.75 inches in length and 0.375 inches to 0.125 inches in diameter. 

2.1.3 The Lead Rod Outlet 
      The lead rod outlet, as shown in Figure 6, is a casing made of hi-impact plastic that envelops the 0.012-inch lead rods. Its purpose is to provide reinforcement to the lead and prevent it from breaking while in use. The lead rod outlet is coated with a silver chrome finish and is connected to a white plastic fitting inside the cone cap. Its design helps ensure the smooth and uninterrupted flow of lead from the mechanical pencil. It measures 0.0866 inches in length and 0.0781 inches to 0.0313 inches in diameter. 

2.2 The Barrel Assembly 
      The barrel assembly depicted in Figure 7 is a plastic casing that encloses and protects the internal mechanisms, including the 0.012-inch lead rods and eraser. The assembly also features a chrome pocket clamp holder. The barrel assembly is designed to balance the mechanical pencil while in use, resting on the index finger, and is attached to the gripping barrel. Its purpose is to ensure the stability and smooth operation of the pencil during writing or drawing.
The barrel assembly consists of four main components:

1) the hourglass barrel

2) the pocket clamp holder

3) the lead rod ejector

4) the removable eraser

2.2.1 The Hourglass Barrel 
      The hourglass barrel, depicted in Figure 8, is a hollow cast casing created to hold 0.012-inch lead rods and provide balance for the Mechanical Pencil on the user’s index finger or knuckle during writing. This primary component of the Mechanical Pencil is constructed from durable green high-impact plastic. Except for the lead rod exit and detachable eraser, all other parts connect to the hourglass barrel, which serves as the central body of the Mechanical Pencil. It measures 1.75 inches in length and 0.375 inches to 0.5 inches in diameter. 

2.2.2 The Pocket Clamp Holder 
      Refer to Figure 9 for the pocket clamp holder, a securing accessory designed to hold the Mechanical Pencil by gripping onto T-shirt breast pockets. The holder comprises a cap that attaches to the upper part of the hourglass barrel and a bendable plastic clamp extending from the cap. The Mechanical Pencil is held in place around T-shirt pockets by sliding between the hourglass barrel and the pliable plastic clamp. Made from high-impact plastic and coated in a silver chrome finish. It measures 1.75 inches in length and 0.5 inches in diameter.

2.2.3 The Lead Rod Ejector 
      The lead rod ejector illustrated in Figure 10, is a retractable button made of durable black plastic, which is used to secure the eraser and to push out 0.012-inch lead rods from the lead rod outlet situated at the bottom of the mechanical pencil. It is connected to the hourglass barrel inside the pencil. It measures 0.25 inches in length and 0.375 inches in diameter.

2.2.4 The Removable Eraser 
      The removable eraser, illustrated in Figure 11, is a cylindrical plug made of white rubber, designed to fit into the opening of the lead rod ejector. It serves the purpose of erasing lead marks on paper. It measures 0.375 inches in length and 0.25 inches in diameter.


2.3 The lead Rods 
       The lead rods are made of a mixture graphite and clay which is then compressed and backed to form a thin and cylindrical rod. After the lead rods have been loaded, use the eraser to plug the opening and stop the lead rods from falling out. A lead rod can then be ejected out of the lead rod outlet once the lead rod ejector has been pressed down by the thumb. It measures 0.012 inches.

            Figure 12: Lead Rods

3. Conclusion 
      The Mechanical Pencil is a precise writing tool that offers numerous benefits over traditional wooden pencils. Its key features include the ability to replace 0.012-inch lead rods, allowing it to last a lifetime. The thin lead rods provide detailed writing and drawing without the need for constant sharpening, which traditional pencils require. Additionally, the Mechanical Pencil maintains its size and shape without becoming cumbersome, unlike traditional pencils that can become difficult to use after becoming too short. Finally, the rubber grip barrel helps prevent calluses from forming during prolonged use.

                                                                   REFERENCES 

Akter, A. (2018, December). Technical Description of a Mechanical Pencil. CUNY Academic Commons. 
      https://afsportfolio.commons.gc.cuny.edu/technical-description/

History of the Mechanical Pencil – Inventor of Mechanism. (n.d.). Retrieved from 
      http://www.historyofpencils.com/writing-instruments-history/history-of-mechanical-pencils/