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First Principles Of Mechanical And Engineering Drawing Pdf

first principles of mechanical and engineering drawing pdf

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Pe Mechanical Engineering Machine Design And Materials Pdf

An engineering drawing is a type of technical drawing that is used to convey information about an object. A common use is to specify the geometry necessary for the construction of a component and is called a detail drawing.

Usually, a number of drawings are necessary to completely specify even a simple component. The drawings are linked together by a master drawing or assembly drawing which gives the drawing numbers of the subsequent detailed components, quantities required, construction materials and possibly 3D images that can be used to locate individual items.

Although mostly consisting of pictographic representations, abbreviations and symbols are used for brevity and additional textual explanations may also be provided to convey the necessary information. The process of producing engineering drawings is often referred to as technical drawing or drafting draughting.

Only the information that is a requirement is typically specified. Key information such as dimensions is usually only specified in one place on a drawing, avoiding redundancy and the possibility of inconsistency. Suitable tolerances are given for critical dimensions to allow the component to be manufactured and function.

More detailed production drawings may be produced based on the information given in an engineering drawing. Drawings have an information box or title block containing who drew the drawing, who approved it, units of dimensions, meaning of views, the title of the drawing and the drawing number. Technical drawing has existed since ancient times. Complex technical drawings were made in renaissance times, such as the drawings of Leonardo da Vinci.

Modern engineering drawing, with its precise conventions of orthographic projection and scale , arose in France at a time when the Industrial Revolution was in its infancy. Rolt 's biography of Isambard Kingdom Brunel [2] says of his father, Marc Isambard Brunel , that "It seems fairly certain that Marc's drawings of his block-making machinery in made a contribution to British engineering technique much greater than the machines they represented.

For it is safe to assume that he had mastered the art of presenting three-dimensional objects in a two-dimensional plane which we now call mechanical drawing. It had been evolved by Gaspard Monge of Mezieres in but had remained a military secret until and was therefore unknown in England.

Engineering drawings specify requirements of a component or assembly which can be complicated. Standards provide rules for their specification and interpretation. Standardization also aids internationalization , because people from different countries who speak different languages can read the same engineering drawing, and interpret it the same way. For centuries, until the post-World War II era, all engineering drawing was done manually by using pencil and pen on paper or other substrate e.

Since the advent of computer-aided design CAD , engineering drawing has been done more and more in the electronic medium with each passing decade. Today most engineering drawing is done with CAD, but pencil and paper have not entirely disappeared. Some of the tools of manual drafting include pencils, pens and their ink, straightedges , T-squares , French curves , triangles, rulers , protractors , dividers , compasses , scales, erasers, and tacks or push pins.

Slide rules used to number among the supplies, too, but nowadays even manual drafting, when it occurs, benefits from a pocket calculator or its onscreen equivalent. And of course the tools also include drawing boards drafting boards or tables. The English idiom "to go back to the drawing board", which is a figurative phrase meaning to rethink something altogether, was inspired by the literal act of discovering design errors during production and returning to a drawing board to revise the engineering drawing.

Drafting machines are devices that aid manual drafting by combining drawing boards, straightedges, pantographs , and other tools into one integrated drawing environment.

CAD provides their virtual equivalents. Producing drawings usually involves creating an original that is then reproduced, generating multiple copies to be distributed to the shop floor, vendors, company archives, and so on. The classic reproduction methods involved blue and white appearances whether white-on-blue or blue-on-white , which is why engineering drawings were long called, and even today are still often called, " blueprints " or " bluelines ", even though those terms are anachronistic from a literal perspective, since most copies of engineering drawings today are made by more modern methods often inkjet or laser printing that yield black or multicolour lines on white paper.

The more generic term "print" is now in common usage in the U. Almost all engineering drawings except perhaps reference-only views or initial sketches communicate not only geometry shape and location but also dimensions and tolerances [1] for those characteristics. Several systems of dimensioning and tolerancing have evolved. The simplest dimensioning system just specifies distances between points such as an object's length or width, or hole center locations.

Since the advent of well-developed interchangeable manufacture , these distances have been accompanied by tolerances of the plus-or-minus or min-and-max-limit types. Coordinate dimensioning involves defining all points, lines, planes, and profiles in terms of Cartesian coordinates, with a common origin.

A variety of line styles graphically represent physical objects. Types of lines include the following:. In most cases, a single view is not sufficient to show all necessary features, and several views are used. Types of views include the following:. A multiview projection is a type of orthographic projection that shows the object as it looks from the front, right, left, top, bottom, or back e. The origin and vector direction of the projectors also called projection lines differs, as explained below.

Until the late 19th century, first-angle projection was the norm in North America as well as Europe; [4] [5] but circa the s, third-angle projection spread throughout the North American engineering and manufacturing communities to the point of becoming a widely followed convention, [4] [5] and it was an ASA standard by the s.

As shown above, the determination of what surface constitutes the front, back, top, and bottom varies depending on the projection method used.

Not all views are necessarily used. In addition to the six principal views front, back, top, bottom, right side, left side , any auxiliary views or sections may be included as serve the purposes of part definition and its communication.

View lines or section lines lines with arrows marked "A-A", "B-B", etc. Sometimes a note tells the reader in which zone s of the drawing to find the view or section. An auxiliary view is an orthographic view that is projected into any plane other than one of the six primary views. Using the auxiliary view allows for that inclined plane and any other significant features to be projected in their true size and shape. The true size and shape of any feature in an engineering drawing can only be known when the Line of Sight LOS is perpendicular to the plane being referenced.

It is shown like a three-dimensional object. Auxiliary views tend to make use of axonometric projection. When existing all by themselves, auxiliary views are sometimes known as pictorials. An isometric projection shows the object from angles in which the scales along each axis of the object are equal.

Isometric projection is a type of axonometric projection. The other two types of axonometric projection are:. An oblique projection is a simple type of graphical projection used for producing pictorial, two-dimensional images of three-dimensional objects:. In both oblique projection and orthographic projection, parallel lines of the source object produce parallel lines in the projected image. Perspective is an approximate representation on a flat surface, of an image as it is perceived by the eye.

The two most characteristic features of perspective are that objects are drawn:. Projected views either Auxiliary or Multiview which show a cross section of the source object along the specified cut plane. These views are commonly used to show internal features with more clarity than may be available using regular projections or hidden lines. In assembly drawings, hardware components e. Section view is a half side view of object.

Plans are usually "scale drawings", meaning that the plans are drawn at specific ratio relative to the actual size of the place or object. Various scales may be used for different drawings in a set. Site plans are often drawn at or Scale is a nuanced subject in the use of engineering drawings. On one hand, it is a general principle of engineering drawings that they are projected using standardized, mathematically certain projection methods and rules.

Thus, great effort is put into having an engineering drawing accurately depict size, shape, form, aspect ratios between features, and so on. And yet, on the other hand, there is another general principle of engineering drawing that nearly diametrically opposes all this effort and intent—that is, the principle that users are not to scale the drawing to infer a dimension not labeled.

The explanation for why these two nearly opposite principles can coexist is as follows. The first principle—that drawings will be made so carefully and accurately—serves the prime goal of why engineering drawing even exists, which is successfully communicating part definition and acceptance criteria—including "what the part should look like if you've made it correctly. And thus the great temptation to do so, when a dimension is wanted but was not labeled.

The second principle—that even though scaling the drawing will usually work, one should nevertheless never do it—serves several goals, such as enforcing total clarity regarding who has authority to discern design intent, and preventing erroneous scaling of a drawing that was never drawn to scale to begin with which is typically labeled "drawing not to scale" or "scale: NTS".

When part definition is defined mathematically via a solid model, the assertion that one cannot interrogate the model—the direct analog of "scaling the drawing"—becomes ridiculous; because when part definition is defined this way, it is not possible for a drawing or model to be "not to scale".

A 2D pencil drawing can be inaccurately foreshortened and skewed and thus not to scale , yet still be a completely valid part definition as long as the labeled dimensions are the only dimensions used, and no scaling of the drawing by the user occurs. This is because what the drawing and labels convey is in reality a symbol of what is wanted, rather than a true replica of it. For example, a sketch of a hole that is clearly not round still accurately defines the part as having a true round hole, as long as the label says "10mm DIA", because the "DIA" implicitly but objectively tells the user that the skewed drawn circle is a symbol representing a perfect circle.

But if a mathematical model—essentially, a vector graphic—is declared to be the official definition of the part, then any amount of "scaling the drawing" can make sense; there may still be an error in the model, in the sense that what was intended is not depicted modeled ; but there can be no error of the "not to scale" type—because the mathematical vectors and curves are replicas, not symbols, of the part features. Even in dealing with 2D drawings, the manufacturing world has changed since the days when people paid attention to the scale ratio claimed on the print, or counted on its accuracy.

In the past, prints were plotted on a plotter to exact scale ratios, and the user could know that a line on the drawing 15mm long corresponded to a 30mm part dimension because the drawing said "" in the "scale" box of the title block. Today, in the era of ubiquitous desktop printing, where original drawings or scaled prints are often scanned on a scanner and saved as a PDF file, which is then printed at any percent magnification that the user deems handy such as "fit to paper size" , users have pretty much given up caring what scale ratio is claimed in the "scale" box of the title block.

Which, under the rule of "do not scale drawing", never really did that much for them anyway. The metric drawing sizes correspond to international paper sizes. These developed further refinements in the second half of the twentieth century, when photocopying became cheap.

Engineering drawings could be readily doubled or halved in size and put on the next larger or, respectively, smaller size of paper with no waste of space.

And the metric technical pens were chosen in sizes so that one could add detail or drafting changes with a pen width changing by approximately a factor of the square root of 2.

A full set of pens would have the following nib sizes: 0. However, the International Organization for Standardization ISO called for four pen widths and set a colour code for each: 0.

All ISO paper sizes have the same aspect ratio, one to the square root of 2, meaning that a document designed for any given size can be enlarged or reduced to any other size and will fit perfectly.

Given this ease of changing sizes, it is of course common to copy or print a given document on different sizes of paper, especially within a series, e. The U. There were also once British paper sizes, which went by names rather than alphanumeric designations. Technical lettering is the process of forming letters, numerals, and other characters in technical drawing. It is used to describe, or provide detailed specifications for an object.

With the goals of legibility and uniformity, styles are standardized and lettering ability has little relationship to normal writing ability.

First Principles of Mechanical and Engineering Drawing

Download the adobe reader if you've purchased your plans in. The free version of PDF Architect already allows you to view, rotate, delete and rearrange pages as well as merge multiple documents. Buy a cheap copy of Architectural Drawing for the Building book. Architectural Design. Download size is 18 MB approx and the download link will instantly become available to you and it will always remain active in your SourceCAD dashboard. With practice you will find sketching to be fun. Architecture for Humanity works with communities around the world on site specific projects from a basketball court with an integrated rainwater collection system in Mahiga, Kenya to housing projects in Biloxi, Mississippi in response to damage done by Hurricane Katrina.

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. To make the drawings easier to understand, people use familiar symbols , perspectives , units of measurement , notation systems, visual styles, and page layout. Together, such conventions constitute a visual language and help to ensure that the drawing is unambiguous and relatively easy to understand. Many of the symbols and principles of technical drawing are codified in an international standard called ISO The need for precise communication in the preparation of a functional document distinguishes technical drawing from the expressive drawing of the visual arts.

first principles of mechanical and engineering drawing pdf

Download PDF. Excerpt from First Principles of Mechanical and Engineering Drawing The greater part Of the subject matter Of this book appeared in a series Of.


Pe Mechanical Engineering Machine Design And Materials Pdf

An engineering drawing is a type of technical drawing that is used to convey information about an object. A common use is to specify the geometry necessary for the construction of a component and is called a detail drawing. Usually, a number of drawings are necessary to completely specify even a simple component.

The question required candidates to use the principle of tangency of arcs and lines. Principles of first and third angle orthographic projection 39 7.

Engineering drawing

By Dennis E. Engineering Drawing From First Principles is a guide to good draughting for students of engineering who need to learn how to produce technically accurate and detailed designs to British and International Standards. Written by Dennis Maguire, an experienced author and City and Guilds chief examiner, this text is designed for use on Further Education and University courses where a basic understanding of draughtsmanship and CAD is necessary. More than just a series of tests, the book helps assess current understanding, diagnose areas of weakness and directs the student to further help and guidance. This is a self-contained text, but it will also work well in conjunction with the highly successful 'Manual of Engineering Drawing', by Simmons and Maguire. Open navigation menu. Close suggestions Search Search.

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Ebook `First principles of mechanical and engineering drawing`: ebooks list of H Holt-Butterfill. download b/w PDF (original scan) · download EPUB.


 Мистер, - сказала она дрожащим голосом, - я не говорила вам, как меня зовут. Откуда вы узнали. ГЛАВА 74 Шестидесятитрехлетний директор Лиланд Фонтейн был настоящий человек-гора с короткой военной стрижкой и жесткими манерами. Когда он бывал раздражен, а это было почти всегда, его черные глаза горели как угли. Он поднялся по служебной лестнице до высшего поста в агентстве потому, что работал не покладая рук, но также и благодаря редкой целеустремленности и заслуженному уважению со стороны своих предшественников.

Он надеялся, что не совершает ошибку. - Сьюзан, - начал он, - этого не должно было случиться.  - Он провел рукой по своим коротко стриженным волосам.  - Я кое о чем тебе не рассказал.

В некотором отдалении от него возникла фигура человека, приближавшегося медленно и неотвратимо. В руке его поблескивал пистолет. Беккер, отступая к стене, вновь обрел способность мыслить четко и ясно.

Агенты связались с ним, когда он находился в Южной Америке, и сообщили, что операция прошла неудачно, поэтому Фонтейн в общих чертах уже знал, что случилось. Тут вступил агент Колиандер: - Как вы приказали, мы повсюду следовали за Халохотом.

Узкая лестница спускалась к платформе, за которой тоже виднелись ступеньки, и все это было окутано красным туманом. Грег Хейл, подойдя к стеклянной перегородке Третьего узла, смотрел, как Чатрукьян спускается по лестнице. С того места, где он стоял, казалось, что голова сотрудника лаборатории систем безопасности лишилась тела и осталась лежать на полу шифровалки.

В этой встрече было что-то нереальное - нечто, заставившее снова напрячься все его нервные клетки. Он поймал себя на том, что непроизвольно пятится от незнакомцев. Тот, что был пониже ростом, смерил его холодным взглядом.

Мысли ее по-прежнему возвращались к сотруднику лаборатории систем безопасности, распластавшемуся на генераторах. Она снова прошлась по кнопкам. Они не реагировали. - Выключите ТРАНСТЕКСТ! - потребовала .

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