The objects, results, or end products generated from constraint-based modeling software are derived from the dimensions and constraints that define the geometry of their features.
Whenever a modification or change has to be made, the modified or new part is re-created from the original part which is based on the original definitions.
Constraint-based modeling is also called feature-based modeling because its individual models consist of combinations of features.
The constraint model is made up of individual features and their relationships with other features, defined by dimensions and constraints.
Each feature (which is defined by specific properties) is a basic piece of a constraint-based solid model. To create a feature, you have to specify the geometric constraints that apply to it; then specify the size parameters and use them to generate the feature.
If a component, part, or element of the feature is modified or changed, the modeling software can be used to regenerate the modified feature in accordance with the constraints that define or are assigned to it.
Apart from defining relationships between features, constraint-based modeling software can be used to apply constraints and parameters across parts in an assembly or assembled structure (such as a group of machine parts that fit together to form a self-contained unit). As a result, when a part is changed, any related parts in the assembly can also be updated.
Because constraint-based modeling software can regenerate features and parts from the relationships stored in its database, the planning aspect of constraint-based relationships is crucial to generating useful and efficient constraint-based models that clearly reflect the design intent of products, parts, or objects.
Advantages of constraint-based model/modeling
During the evolution of designs, constraint-based models can be easily updated by altering the relationships and sizes that define them, respectively.
Categories of designs can be created because of the ease with which constraint-based models can be updated; also, it is possible to analyze, make changes, reanalyze, and make changes to the model again and again.
Constraint-based model makes it easy to update related parts to a new size after dimensions are changed.
Constraint-based model analyzes mass properties such as the weight and volume data during design so that the resulting structure behaves in the desired way.
Constraint-based model enhances the amount of time that can be used to optimize a design; this is possible because the model makes it possible for analysis to be incorporated earlier in the design process.
By focusing on the design intent for any product, constraint-based modeling helps modelers to be more imaginative, carefully consider or reconsider the function and purpose of the item being designed, and improve designs—thereby even resulting in better designs.
Types of constraints used to define and drive the constraint-based model geometry
Each object or product in a constraint-based model is defined by the constraints or dimensions/sizes and geometric relationships stored in the model and used to produce the object or product. Two basic types of constraints are used to define and drive the constraint-based model geometry:
Size constraints are the dimensions that define the model or its geometry. The type of dimensions chosen and how they are placed, respectively, are important aspects of capturing the design intent behind a model.
Geometric constraints determine the limits and maintain the geometric properties of a product or object, such as circularity, tangency, horizontality, verticality, etc. These geometric constraints are equally important in capturing design intent.
In constraint-based modeling, the term parameter refers to a named quantity that has a value that can be changed; just like a variable, it can be used to define other parameters.
However, unlike a variable, a parameter is not abstract—implying that it will always have or be assigned a value to represent a model.
For instance, the parameter called length can be assigned and defined by a value, such as 20. (Width is also a dimension but a different type of parameter.) On the other hand, the same length can be defined as having a value that is two times the width of the same object: the size or dimension of the length can be defined as: “2 × width”—meaning that, instead of assigned, the length parameter can be calculated using the width. In that case, if the value of the width is changed, the length would be automatically updated to the new value of “2 × width”.
The parameters that define and drive the object or model geometry are indicated on reproduced drawings. If the parameter value for the breadth, width, or length of a part of an object is changed, the whole object would be updated automatically.
It is important to note that the dimensions (used to define individual features) in a constraint-based model can behave in different ways. A dimension can be:
A parameter: this aspect is used in equations that “drive” the size of a model feature.
A reference dimension (often called driven dimension): this aspect derives its value from the model geometry; however, it is not a size constraint for the model.
A size constraint (often called driving dimension): this aspect of the model feature can be updated when the dimension is altered or modified.
A dimension: generally, this aspect is just any text whose value either has or does not have a relationship with the model geometry, regardless of whether or not it is included on a drawing or model view.
A combination of all the above.
Driving dimensions help to moderate the size of a feature element in the constraint-based model for an object or idea. Each driving dimension has two parts: a numerical value and a name. Each name makes it possible for the dimension it represents to be used in equations or relationships that define different parts of the model geometry. The numerical value, on the other hand, can be derived from an equation or represented by a number that defines the dimension.
Constraint-based modeling software lets users switch their display between the named and numeric dimensions in their respective models.
Like the geometric constraints used in constraint-based modeling, the size parameters can also establish relationships between features of the model component in formulas.
The operators used in the equations that express constraint-based dimensions are similar to those used in a spreadsheet or other types of programming notation.
In fact, many modelers have made it easy for users to import and export dimensions or numeric values from a completely different application; for instance, a spreadsheet.
When handling information from other applications, it is possible to use complex formulas to calculate the sizes in the other program; thereafter, the obtained results or values can then be imported back into the modeling package which, like others, has its own syntax and notation.
The exponential growth of the number of research works and publications has quickly developed solid modeling into a large body of knowledge, and the technology that backs it is applied in lots of commercial solid modeling software systems which have greatly cut down maintenance and manufacturing costs, improved product quality, and enhanced design productivity.
Solid models and modeling play a significant role in the manufacturing and assembling of parts and are used in many industries, ranging from health care to engineering to entertainment.
What is a solid model & solid modeling?
A solid model can be defined as a digital demonstration or presentation of the physical geometry of an existing or conceived concept, image, idea, or object. Solid models are easy to evaluate and comprehend, and can replace physical models; plus, they are highly visual and accurate if modelled accurately.
Solid modeling can be defined as the process of demonstrating or representing the physical geometry of an existing or conceived concept, image, idea, or object—usually on a smaller scale. It can also be defined as the process of using a serialized set of additive and subtractive programs to construct a 3D model. Generally, the geometry is completely depicted in 3D space—hence the term “3D solid modeling”.
Solid models consist of common shapes such as cylinders, cubes, triangles, squares, or spheres that are made of 2D sketches; for instance, the solid model—or specifically, the “3D solid model”—of a cube consists of six flat square surfaces that are coupled or joined together.
However complex it may be, any 3D solid modelling can be disassembled into sub-shapes that comprise of/are formed with one or more 2D sketches.
Solid modelers usually specify points, lines, curves, dimensions, positions, and surfaces and assemble them together by using intersections, unions, or difference operators to define representations of the boundaries of objects.
Many solid modelers also store the mathematical processes or operations used to produce various features of a solid model or during solid modeling. This makes it possible to easily and quickly make edits.
Solid models store the edge and vertex information of a 3D wireframe modeler, information regarding the volume to be incorporated or contained inside an object, and the surface definitions of a surface modeler.
Solid models contain information about the volumes (of objects) which are very important in many engineering calculations. It’s possible to calculate moments of inertia, weights, mass properties, and centroid from a solid model, even during the refinement process.
The end product of any solid modeling process is a representation is a complete, detailed, and clearly defined or unambiguous digital estimation of an object’s geometry or assembly of objects such as a car, a vehicle’s engine, a propeller, or an entire aircraft.
Applications of 3D solid models/modeling
Generally, the applications of solid model/modeling include:
to interpret how designed products will actually look like, and acquire an in-depth understanding of design images
to visualize specific body tissues like blood tumors and vessels
to employ efficient facilities for graphically selecting or editing features of parts that are being designed
to obtain immediate feedback that can help perform and check each design step
to acquire information needed for other analyses such as Finite element analysis (FEA) method
to disassemble complex objects into smaller shapes that can enable easier calculation of stress, strain, heat transfer, etc.
to help incorporate changes and test new models with FEA analysis again
to design orthotics, prosthetics, orthotics, and other dental and medical and dental devices—this process is sometimes called “mass customization”
to produce polygon mesh models for rapid prototyping which can help surgeons prepare for difficult surgeries
to combine polygon mesh models with CAD solid modeling and design hip replacement parts
to carry out computational analysis of complex biological processes like blood flow and airflow
to conduct computational simulation of implants (in living organisms) and new medical devices
to create various characters and make movies in the entertainment industry
One outstanding quality of surface models is the improved appearance of their surfaces and the ability to use its [appearance] complicated definitions for computer-aided manufacturing (CAM).
Evidence proves that customers purchase products, not only based on how they function, but also on their styling or how aesthetically pleasing they are, with or without visually expressing how their back edges actually appear.
By using lighting and different materials in most surface modeling softwares to create and present a realistically shaded model of a product to potential customers, you can actually evaluate their [customers’] reaction—pleasure, displeasure, or otherwise—to seeing it.
Many real-life consumer products often start out as a surface model and their interior parts are engineered to accommodate or somewhat conform to the shape of the exterior part(s).
Using surface models is cost-effective and could increase savings when used in place of physical prototypes or in place of actual products for promotional purposes. The cost-effectiveness of surface modeling depends on the complexity or difficulty of the surface, the level of accuracy it requires, and the potential purpose of the modeling.
The surface definitions of surface models eliminate the ambiguity that is inherent in some wireframe models: they make it possible for you to view the front edges or surfaces and holes by hiding the “invisible” parts of the model.
It is true that complex surfaces can be difficult to model, but it is possible to manufacture irregular shapes that are difficult to document systematically in 2D views if their complex surfaces, which are defined by a surface model, can be exported to numerically controlled machines.
Surface models (and solid models too) can be used to assess interference and fitness before a product is eventually manufactured. Oftentimes, solid models can be changed into surface models and vice versa.
Although surface models define surfaces and often provide information about the surface area of a part of a product, such information can save time, especially when a complex surface is involved. However, the accuracy of calculations in surface models may depend on the method employed by the software to store product surface data.
Most surface modeling softwares are programmed with a matrix/list of an object’s or a part’s vertices and how they are linked to one another to form edges in the CAD database which can mathematically generate surfaces (from points, lines, and curves) between an object’s vertices.
During the process of creating surface models, some surface modelers save additional information that defines and indicates the inner/inside and outer/outside parts of a surface.
This is often accomplished by saving a “surface normal”—a leading or directional line that is normal or perpendicular to the outer part of the surface. This feature makes it easy to shade and render the model.
The basic methods used to create surface models, are as follows:
Extrusion and revolution
Mesh surfaces or meshes
NURBS-based surfaces, or spline approximations
1. Extrusion and revolution
It’s possible to define a surface by using a 2D shape or profile and the axis or course about which it revolves (circles around or moves about in an orbit) or extrudes (forms or takes shape by forcing through an opening).
Figures 1 and 2 below show a surface model that is created by revolution, and the axis of revolution and profile used to create it. Surface primitives (such as cylinders, planes, and cones) are sometimes used as building blocks and can be created from the revolution or extrusion of regular geometric entities.
Figure 1
Figure 2
The surface model (figure 1) above was created by revolving the profile (figure 2) about the axis (same figure 2). (Source: Technical Drawing with Engineering Graphics, 15th edition.)
2. Mesh surfaces or meshes
In the CAD database, vertices or matrix of vertices are used to define flat plane surfaces, and the 3D location of each vertex defines each individual mesh surface. Below, figure 5 shows the matrix/list of a mesh’s vertices, while figures 3 and 4 show the wireframe view and rendered view, respectively.
Mesh surfaces are very important in modeling uneven surfaces in which it isn’t necessary to use completely smooth surfaces. Instead of producing a mesh surface with a slightly bumpy appearance, some CAD modeling packages allow users to define surfaces by a smoothed representation.
Figure 3
Figure 4
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Figure 5
A Mesh Surface: A mesh surface comprises a series of planar surfaces that are defined by a matrix or list of vertices (figure 5), a wireframe view (figure 3), and a rendered view (figure 4). (Source: Technical Drawing with Engineering Graphics, 15th edition.)
3. NURBS-based surfaces, or spline approximations
The mathematics that is behind and guides non-uniform rational B-spline curves also forms the basis for the method which is used to create surface models and surfaces in most surface modelling systems.
A set of vertices (in 3D) that are used to mathematically define smooth surfaces, are also used to define non-uniform rational B-spline (NURBS) surfaces.
The advantage that the surface modelers who use NURBS have is that, because rational curves and surfaces can be used to generate both free-form curves and analytical forms (such as cylinders, planes, lines, and arcs), the CAD database doesn’t necessarily have to be equipped with different techniques for creating surfaces by using a surface primitive, revolution, extrusion, or mesh.
Some extruded and revolved surfaces can be “lofted” or “swept”, and spline curves can be used as program or input for extruded and revolved surfaces.
“Lofting” is a term used to define any surface that fits into a series of curves that don’t intersect or meet at any point with each other. On the other hand, “sweeping” is a process whereby a surface is created by sweeping a cross section or curve along one or more “paths”.
In both cases—lofting or sweeping—the overall surface merges from the shape of one curve to the shape of the next curve, as shown in figures 6 and 7 below.
Figure 6
Figure 7
A lofted surface (figure 6) merges a series of curves that don’t intersect into a smooth surface, while a swept surface (figure 7) sweeps a cross section or curve along a curved path and merges the characteristics of both into a smooth surface model (Source: Technical Drawing with Engineering Graphics, 15th edition.)
Figure 8
Figure 9
NURBS surfaces can also be created by meshing curves that are perpendicular or cut across each other, as shown in figure 8 and 9 above. (Source: Technical Drawing with Engineering Graphics, 15th edition.)
Note
If you want to create a surface model, you don’t have to create an entire surface at once. Only entities (technically referred to as “patches”) would be enough, but you have to combine the entities or patches into a continuous model and to create complex surfaces.
Each patch can be approximated or interpolated just like a spline curve can, and surface patches are connected together by employing mathematical methods to merge the approximated edges of the patches and eventually create smooth joints.
It is important to note that sometimes or where necessary, trimming is used to create complex surface patches. For instance, a modeler might start out with a circular patch but trim it to a triangular patch and eventually merge it with other surface patches.
Some surface modeling systems use Boolean operations, while others don’t. It can be difficult to use the systems that don’t employ Boolean operations (or proficient tools for trimming surfaces) to create a feature such as a rectangular hole through a curved surface because the exact shape of the surface and hole has to be defined by assigning or fixing its edges.
There are three main types of 3D models or modeling methods integrated into CAD systems for a single software package, and each has its own strength and weakness: wireframe models/modeling, surface models/modeling, and solid models/modeling.
Although there are other types of 3D models that can be used in CAD systems for technical & engineering drawings/graphics and designs, most of them exist as a subset of the three main types of models, or they can be used individually for specific purposes.
1. Wireframe model
The Wireframe model/modeling method was the first 3D modeling method to be established. Wireframe models are often used as a starting point in 3D modeling since they eventually create a “frame” for 3D structures.
A wireframe is a three-dimensional model that only includes vertices and lines; it doesn’t contain surfaces, textures, or lighting like a 3D mesh. Instead, a wireframe model is a 3D image comprised of only “wires” that represent three-dimensional shapes.
Generally, “wireframe model/modeling” refers to any computer screen display of a model in regard to only the edges and contours of the object or artifact it represents.
Wireframes provide the most basic representation of a three-dimensional scene or object: using simple lines and curves, a wireframe model can represent a “skeleton” for building a 3D object.
Wireframe models express the contours and edges of objects by using circles, lines, and arcs orientated in 3D. The portrayal of contours and edges in the wireframe model was developed from 2D modeling practices.
The wireframe modeling method derived its name from the process of mentally or visually representing objects, sculptures, or carvings with wires as shown in Figures 1, 2, and 3 below.
Figure 1: The Wireframe model (lines, arcs, and curves in 3D) of an artefact (Source: Quora)
Figure 2: The Wireframe model of a car (Source: DepositPhotos)
Figure 3: The Wireframe model of the world (Source: PngEgg)
A wireframe model can be created in the same way a 2D CAD drawing is created. Simple geometric tools (such as circles, lines, and arcs) are drawn in 3D to express each edge where the surfaces on an object intersect.
Wireframe models don’t look as realistic or “close to reality” as some other models because they incorporate surfaces or boundaries that are often shaded.
A wireframe model can help to visualize 3D equipment which is more difficult to visualize when represented or expressed in 2D. In many cases, it is advisable not to overlook wireframe during the design of an object.
The major advantage of wireframe 3D models is that they provide a single and clear understanding of some shapes and make it possible for objects not to be represented unambiguously, especially when expressed using multi-views.
2. Surface model
CAD surface modeling/models specify limits and define an artifact or shape by using the stored information about its surface to create a realistic visual or mental picture or impression.
However, surface models do not assign any material thickness to surfaces, and the outer surfaces of objects (balls, boxes, cubes, etc.) can be shaded between or around the limits specified and defined by surface models.
Generally, surface models focus on modeling the outer/outside parts of objects, artefacts, shapes, or products, instead of the inner and mechanical parts within.
Figure 4: Surface modeling for Audi car (Source: GrabCAD)
The information (or definitions) about an artefact is stored in the CAD database. This information represents the outer or external boundaries of surfaces that could form part of the 3D model. (The process of storing the definitions of surfaces in the database is called “boundary representation” [BREP].)
To create a surface model, an entire surface doesn’t need to be created at once: only pieces or “patches” are combined into a continuous model. In summary, surfaces can be created from bits or pieces technically referred to as “patches”.
Each patch can be interpolated or approximated like a spline curve. A patch can be regarded as a “coon’s patch”—this refers to an interpolated surface that is defined by four boundary curves which have points that can be interpolated using mathematical methods.
The surface models employed in computer-aided manufacturing (CAM) need to operate at a high level of accuracy to produce really good and smooth surfaces that may require fewer control points to make their curves more fluid.
3. Solid model
The term “solid models or modeling” is a technique used by solid modelers or designers to create a representation (called a solid) of a solid object. Unlike surface and wireframe models, solid models ensure that objects are geometrically correct and all surfaces meet precisely.
Solid models not only represent the edges, vertices, and surfaces of the part, they also help determine the locations of points in space within an object or outside it.
In terms of storing information concerning the volume occupied by an object of artifact, solid models go way beyond surface models. In fact, solid models record information about the vertex and edge of the 3D wireframe modeler, the surface modeler’s surface definitions, and volume.
Because many solid modelers store the operations used to produce features, it is possible to quickly edit features of objects and easily test, define, and refine the designs that solid models represent.
Figure 5: Three technical/engineering drawing projections and their corresponding solid (shaded) model (Source: ResearchGate)
Solid models are easy to understand and highly accurate and visual if modelled accurately. Some 3D solid models are often more capable of replacing physical models.
However, 3D solid models work better with analysis packages and contain all the information about the volumes of objects which are very important in many calculations.
During the refinement process of designs, the solid model can be used as a foundation from which centroid, mass properties, moments of inertia, and weight can be estimated as many times as may be needed.
Figure 6: Difference between Wireframe model and Solid Model (Source: LearnMech)
The behavior of an object or its system can be simulated from the information stored in the solid model which can further provide useful information that may be required for other analyses.
Because solid models define entire objects, their information can be used by finite element analysis (FEA) softwares to automatically generate FEA meshes and break up complex objects into smaller objects, thereby making it easier to even calculate material properties such strain, stress, and heat transfer.
Some solid modeling softwares and FEA are structured to provide this and similar types of analysis. Other modeling softwares even permit direct model optimization based on results from FEA, and could be used to produce a new version of the model which the modeler can review further.
Generally speaking, a model is a representation or hypothetical description of a complex process, entity, system, device, or theory that helps to predict its behavior.
A model can also be defined as a small-scale object that is usually built to scale to represent the details of a much larger object.
Models are used in technical and engineering drawings and designs and also preliminary works or construction, as plans from which final products are created; for example a clay model can be created for a real or an eventual casting process.
Models in technical and engineering drawings and designs and preliminary works can be used in testing, perfecting, or honing a final product after understanding and being satisfied with how it behaves; for example, a test model can be created for a solar-powered vehicle.
This article discusses the following types of models used in technical & engineering drawings and designs:
1. Descriptive models
Descriptive models are used in technical and engineering drawings and designs to represent an object, system, entity, device, or process, in either words or pictures.
A descriptive model is a group of written specifications for a design, an object, a system, an entity, a device, or a process.
The major aim of a descriptive model is to describe and provide enough details that can express the image of the final design, object, system, entity, device, process, or product.
Sometimes, descriptive models use representations that are simplified, similar, or equivalent to something that can be more easily understood.
If all the specifications in a descriptive model are adhered to, the final design, object, system, entity, device, process, or product will perform as correctly as expected.
Sketching is another type of descriptive model for the design ideas that are expressed on paper. Two-dimensional (2D) and 3D computer-aided design (CAD) drawings are also descriptive models.
Although, in certain cases, a physical model or prototype is created to be smaller in scale, they are still regarded as another type of descriptive model.
2. Analytical models
Analytical models in technical and engineering drawings and designs help to mathematically or diagrammatically (schematically) represent and predict the future behavior of an object, system, entity, device, process, or product.
For example, an electrical circuit model or simple circuit design model can help to simulate or reproduce the behavior of an actual electrical circuit, or how it would function; therefore, an electrical circuit model is an example of an analytical model.
An effective analytical model helps to determine the best aspects of a system’s, an object’s, an entity’s, a device’s, a process’, or a product’s behavior that should be modelled.
A finite element analysis (FEA) model—such as that used to calculate important properties (for e.g., stresses, temperature, etc.) during the design of a real object, system, entity, device, process, or product—helps to simplify CAD models in a similar way.
A FEA model breaks a model into smaller elements and reduces a complex or complicated system into a series of smaller systems which helps to solve a problem, or understand and estimate certain properties more easily.
Understanding and applying an analytical model requires a good understanding of the difference between the model and the actual system, entity, device, process, or product, in order to be able to interpret any results correctly.
3. Two-dimensional (2D) models
Traditional paper drawings
Two-dimensional (2D) sketches and multi-view paper drawings represent designs for technical and engineering drawings and designs.
All the information that defines an object can be shown on paper drawing through sketch details, but may require many orthographic views which could take a long or longer time to create than CAD drawings would.
Because paper drawings are difficult to modify, the labor costs involved in producing them usually outbalance or outweigh equipment savings.
Paper drawings are not always highly accurate: their accuracy is approximately plus or minus one fortieth (1/40) of the drawing scale and makes paper drawings not particularly measurable.
2D CAD Models
Although two-dimensional (2D) CAD models share the visual characteristics of paper drawings, they are much more accurate than paper drawings and easier to modify.
CAD models represent the full size of objects, unlike paper drawings which usually don’t. Also, in CAD models you can “snap” to exact locations on objects, so as to be able to determine sizes and distances.
CAD systems have standard symbols which are easy to add and change; in addition, they have many editing tools that enable users to quickly edit and reuse drawing geometry.
Two-dimensional 2D CAD drawings can be easily and quickly printed to any desired scale, and different types of information can be singled onto several layers; this gives the model an advantage and makes it more flexible than paper drawing.
Computer-aided design accurately defines the positions of lines, arcs, and other geometry. If you query the AutoCAD database, it accurately returns information to you in the form it was originally created.
2D constraint-based modelling
Constraint-based modeling was originally started as a method to create 3D models. Constraint-based 2D models provide users with technical aspects that can help them define 2D shapes based on their individual geometry.
Users can add relationships like tangency and concentricity between entities in a drawing, and once a tangential or concentric constraint is added between two shapes or drawings (for e.g., circles), they will be constrained to remain tangential or concentric, and a user will be alerted if they attempt to make a change that will violate a selected geometric constraint.
The dimensions used in drawings constrain the sizes of the features of the drawings, and the relationships defined between components of the 2D model are retained by the software that is used when making changes to any drawing.
Geometric constraints are highly valuable tools, but must be applied with a proper understanding of basic drawing geometry if any benefit is to be derived from them.
Examples of constraints in AutoCAD 2016
The following are the constraints that define 2D objects’ respective geometry in AutoCAD:
“Vertical”: This constrains lines or pairs of points on objects to remain parallel to only the y-axis
“Horizontal”: This constrains lines or pairs of points on objects to remain parallel to only the x-axis
“Parallel”: This constrains two selected lines to remain parallel to each other
“Perpendicular”: This constrains two selected lines to be at an angle of 90° to each other
“Tangent”: This constrains two curves to be tangent to each other or to their extensions
“Smooth”: This constrains a spline to be contiguous and maintain G2 curvature continuity with another entity
“Concentric”: This constrains two arcs, circles, or ellipses to retain or maintain the same center point
“Coincident”: This constrains two points to stay connected to each other
“Collinear”: This constrains two or more line segments to remain along the same line
“Symmetric”: This constrains two selected objects to remain symmetrical about a specified line
“Equal”: This constrains selected entities to retain or maintain the same size
“Fix”: This constrains points, curve points, or line endpoints to stay in fixed position on the coordinate system
“Angular”: This constrains the angle between two lines to be retained
“Linear”: This constrains the distance between two points along the x- or y-axis to be retained
“Aligned”: This constrains a distance between two points to be retained
“Diameter”: This constrains the diameter of a circle to be retained
“Radius”: This constrains the radius for a curve to be retained
Icons for constraints in AutoCAD 2016
4. Three-dimensional (3D) models
Two dimensional (2D) models must be interpreted in order to correctly visualize 3D objects. Three-dimensional (3D) models are used to convey technical and engineering and designs to people who are unfamiliar with orthographic projection; in addition, they (3D models) are used to evaluate properties of drawings and designs that are undefined in 2D representations.
Physical models
Physical models serve as a source of visual reference and are also called “prototypes” whenever they are created in “full-size” or used to validate a nearly last or final design for production.
Physical models are good visual representations of designs; however, if they are not created from materials that would be used in a design, their weight and other features won’t match the final product.
Physical prototypes help to discover and correct many problems in designs and enable people to interact with physical models and understand how designs would eventually look like, and how they would function.
In certain cases, due to the size of a project, a physical model is created to be smaller in scale than how the final design would be. However, physical prototypes lack flexibility, and once they have been created, it is usually difficult, expensive, and time-consuming to modify or change them.
Therefore, it is advisable to use full-sized physical prototypes late in the design process, when major design changes are less likely to be made.
3D CAD models
Three-dimensional CAD models combine the characteristics of both descriptive models and analytical models and provide the benefits of both a 2D model and a physical (prototype) model.
Three-dimensional CAD models can generate standard 2D multiview drawings for visual representation, as well as rendered and shaded views.
Because 3D CAD models accurately depict the geometry of objects or devices, they can completely describe the shape, size, and appearance of objects or devices in the same way as a physical or scaled model would.
Virtual reality
Virtual reality (also called “VR”) refers to the process of interacting with a 3D CAD model as if it were real. In virtual reality, the model simulates how a user would interact with a real object, device, or system.
The term “virtual prototype” refers to 3D CAD systems that represent objects that are adequately enough to enable people, manufacturers, or designers to acquire the same type of information they would be able to acquire from creating and studying a physical model or prototype.
When a virtual reality display is used, users can be able to immerse themselves in the model and move about or through it and view it from several points of view.
If the conditions of a virtual object are altered, it would react in a certain way and provide feedback, or a sensation of its reaction would be provided to the user or person immersed in the virtual reality they subjected themselves to.
Computer-aided design (CAD) drawings are produced and stored in relationship to a coordinate system, especially Cartesian coordinate system, polar coordinate system, cylindrical coordinate system, and spherical coordinate system.
Regardless of the CAD software system that will be used in 2D and 3D CAD modeling or to produce CAD drawings, it is important to understand the basics of the most widely used coordinate systems in CAD softwares.
Majority of CAD systems use the right hand rule, as applied to coordinate systems. Although it is quite rare, some CAD systems use the left-hand rule.
To get a clear illustration of the right-hand rule, do this: as shown in Figure 1 below, stretch the thumb of your right hand—to represent the direction of the positive x-axis; stretch the index finger of your right hand—to represent the direction of the positive y-axis; and stretch the other remaining fingers of your right hand to represent the direction of the z-axis.
Figure 1: The right hand rule, as applied in coordinate systems (Source: Technical Drawing with Engineering Graphics, 15th edition.)
The right hand rule is also related to the popular Cartesian coordinate system which can be used to express drawings in 2D (x, y) and 3D (x, y, z). When using a computer for 2D (two-dimensional) or 3D (three-dimensional) modeling, the face of your computer screen represents the 2D or x–y plane, and the z-axis represents the axis pointing directly towards you, as indicated in Figure 2 below.
Figure 2: Z-axis pointing towards your direction, as computer screen face represents the 2D or x–y plane. (Source: Technical Drawing with Engineering Graphics, 15th edition.)
Two-dimensional (2D) CAD systems use only the x– and y– coordinates of the Cartesian coordinate system, while 3D CAD systems use the x-, y-, and z– coordinates. When representing a 2D system in a 3D CAD system, the line of view is along the z-axis. Figure 3 below shows an orthographic view or 2D drawing produced with only x and y values, with the z-coordinate set at 0.
Figure 3: Computer screen face showing a CAD drawing in 2D or x–y plane. (Source: Technical Drawing with Engineering Graphics, 15th edition.)
Orthographic views show only two of three coordinate directions, with the line of view generally considered to be along one axis—usually the z-axis. Two-dimensional CAD drawings are the same: they are produced with and represented by x and y coordinates, while the z-axis is the line of view.
As stated, in a CAD system, the 2D (x–y) plane is aligned with the computer screen, while the z-axis is pointing horizontally and directly towards the person using the computer. However, in machining and many other applications, the z-axis is regarded as the vertical axis. Regardless of the name given to an axis, the coordinate axes (x, y, and z) must be perpendicular to each other (mutually perpendicular).
It is more important to understand how to use axes or coordinates in a model/drawing than to name the direction of default axes and planes. As shown in Figure 4 below, the structure of a 3D object is identified by its x, y, and z coordinates, with the location (0, 0, 0) taken as the starting point from which other points are plotted.
Figure 4: The coordinates for a 3D drawing (Source: Technical Drawing with Engineering Graphics, 15th edition.)
Coordinate systems/formats used to specify locations or points
Although 2D and 3D models/drawings are stored in a single Cartesian coordinate system, a CAD user may be drawn into a situation whereby they would be required to specify locations of some features using other coordinate systems.
The most distinctive of these CAD geometry coordinate systems or location methods are absolute coordinates, relative coordinates, polar coordinates, cylindrical coordinates, and spherical coordinates:
Absolute coordinates are locations or points that are at a distance from a common point of origin in a Cartesian System. Locations are established using values on the x-, y-, and even z– axes. For example, in Figure 4 above, the absolute coordinate (3.5, 8, 4) represents a location that is 3.5 units away from the x-axis origin (0), 8 units away from the y-axis origin (0), and 4 units away from the z-axis origin (0). In other words, we can say that the location is (3.5, 8, 4) away from the origin (0, 0, 0). In Figure 5 below, the point of origin (point B) is (0, 0) and there are five absolute coordinates located away from the point of origin (0, 0): A (0, ─4), C (─6, 3), D (6, 4), E (2, ─2), and F (─3, ─5). Generally, absolute coordinates express the position/location of the points of an object with respect to an origin of a given coordinate system.
Figure 5: Absolute coordinates in 2D (Source: Siyavula)
Relative coordinates are locations that are expressed in terms of their relative distances away from a reference point that is not the point of origin. Instead of specifying a location from the actual point origin, a relative coordinate can be used to specify a location in terms of the location’s distance away from a previous location.
Polar coordinates are 2D coordinate systems in which individual locations or points are defined in terms of an angle (in degrees) and distance away from an axis—the axis could be any of x, y, or z Polar coordinates are absolute if they express a location or point in terms of its angle away from an axis and distance from the origin; on the other hand, polar coordinates are relative if they express a location in terms of its angle and distance away from another location that is not the origin.
Cylindrical coordinates are locations that are specified in terms of a radius (r), an angle (θ), and distance a (z) which is usually in the z-axis direction. Any values attached to these terms are relevant for conveying information about locations or points that are on the edge of a cylinder. The radius tells the distance of the point from the center (or origin); the angle expresses the angular inclination of the point away from an axis (for instance, the x-axis shown in Figure 7 below) along which the point is located; and the distance expresses the height of the point on a cylinder. The difference between cylindrical coordinates and polar coordinates is that cylindrical coordinates include a height distance in the z-direction.
Spherical coordinates are locations that are expressed by a radius (ρ), an angle (θ) from the x-axis, and another angle () from a 2D (example: either y–z or x–y) plane. Spherical coordinates express the position of a point on a sphere, with the origin of the coordinate system at the center of the sphere, and the radius indicating the size of the sphere.
Although some people are more naturally gifted in creating technical and engineering designs and drawings, everybody has the ability to create at least something significant, no matter how little, and enhance their level of creativity or design ability if they consistently use certain tools or apply certain techniques over a period of time.
Enhancing creativity in technical and engineering drawings is synonymous with enhancing creativity in any type of sport: study and practice is a necessary requirement. Everybody can start at any level of creativity and improve if they are willing to put in an appreciable amount of effort, both mentally and physically.
So, how can anyone develop new ideas or their creativity in technical and engineering drawings? By consistently and conscientiously engaging in technical or engineering drawing visualization, communication, and documentation and producing drawings (traditional and CAD), anybody can be able to develop a higher capacity to generate more ideas and become more creative and competitive in the world marketplace.
This article discusses the following five proven ways that can be used to enhance creativity in technical and engineering drawings, and make it easier to generate new ideas for drawings:
1. By consistently studying the natural world
The easiest way to enhance creativity is to be a student of the natural world: make it a regular practice to meditate on, ponder upon, and draw the objects that exist in the natural world.
By imagining and analyzing how objects are aligned and living things function and interact together in the environment, it would be possible to obtain so much information and inspiration from the natural world and set a firm foundation to unleash and enhance one’s creativity.
It’s important to note that objects such as spiderwebs and beehives have inspired many structural designs, and birds’ wings have inspired the design of aerodynamic structures. There is quite a lot to learn from nature, just by taking time to study living things and natural objects.
2. By learning from mentors or being part of design groups
In today’s world, most people handle technical and engineering drawings in working or team environments which usually have leaders, experts, or knowledgeable people who are usually more creative and familiar with design drawings.
Being part of a design group and having regular interaction with people who are very creative can play an important role in enhancing one’s own creativity and broadening their understanding of what it takes to generate new ideas.
3. By studying artificial or manufactured products
Artificial or manufactured products contain a great deal of information that can be interpreted by studying or observing them, regardless of whether their parts are assembled or dismantled.
By assembling or dismantling manufactured products, one can make evaluations and acquire a greater understanding of how their parts are designed and work together.
By being inquisitive and seeking how to do things differently or making improvements (in efficiency, performance, speed, etc.) in already-existing manufactured products, one could be well on the way to developing new ideas and enhancing their own creativity.
4. By conducting research on patent drawings
Patent drawings for products are great resources for ideas; researching on/studying patent drawings can enhance one’s creativity and broaden their imagination.
People still have access to patent drawings, even though patents, which are issued by governments, protect drawings and grant their respective owners certain rights to exclude other people from using, making, or selling their products for certain periods of time.
Anybody can search a government’s patent office—if available online—for the current design of a product or an idea. For instance, the USA Patent and Trademark Office’s website (www.uspto.gov), which has strict regulations on how drawings should be presented, contains design drawings that researchers can easily reproduce.
5. By surfing the Internet and examining designs or drawings
There are many outstanding sources for designs and drawings on the Internet (World Wide Web). By spending time to visit engineering and technology sites and read/study technical and engineering drawings, any interested individual can become more familiar with drawings and develop or enhance their own creativity.
The following websites can be useful for studying technical and engineering designs and drawings:
Technical and engineering drawings consist of drawn objects or items that will be eventually produced, manufactured, or constructed in real life; the sizes and dimensions of objects are always expressed by using the units of a particular measurement system.
The two most widely used measurement systems are the “Metric System” (also known as the “International System of Units”), and the “United State Customary Units”; both measurement systems consist of a number of units.
Among the two measurement systems, the metric system is the standard that is mostly used around the world, especially for expressing the sizes and dimensions of the lengths, heights, and widths of objects on technical and engineering drawings.
Various professions use measurement systems in technical and engineering drawings to communicate and document their designs; some examples of professions include civil engineering, environmental engineering, mechanical engineering, architecture, landscape design, industrial design, and manufacturing.
1. The Metric System (International System of Units, or SI Units)
The present-day metric system is the “International System of Units” which is commonly referred to as “SI Units”—an acronym from the French phrase “le Système International d’Unités”.
The International System of Units is a measurement system that was established in 1960 after an international agreement was reached; it is presently the international standard used in expressing the sizes and dimensions of objects.
Although some countries still use U.S. Customary Units to a lesser or greater degree, all countries in the world have adopted the International System of Units.
The most widely used units of the Metric System (International System of Units) are the kilometer (mm), the meter (m), and the millimeter (mm). The centimeter (cm) and the decimeter (dm) are also among the units in the Metric System, but they are rarely used on technical and engineering drawings.
It’s quite common to see some industries using a dual dimensioning system to express the units of the sizes of the dimensions of objects on each of their drawings.
For example, they could use “millimeter” and “inch” together on one drawing, even though millimeter is a unit that belongs to the Metric System (International System of Units) and inch belongs to the U.S. Customary Units.
It has to be noted that using a dual dimensioning system to express the units of the sizes of the dimensions of objects can cause a bit of confusion because the sizes derived by using two different systems may contain rounding errors whenever one unit is converted to another.
Most creators of technical and engineering drawings use Metric System units on dimensions in order to maintain consistency between different units that belong to the same measurement system. In standard practice, the following Metric System units and relationships are often used:
The United States Customary Units is a measurement system that was formalized in 1832 and has been commonly used in the United States since then.
The United States Customary System (USCS or USC) was derived from the English units that were being used in the British Empire before the United States became an independent nation.
The most widely used units in the United States Customary Units are the mile (mi.), the foot (ft.), the inch (in.), and the yard (yd.). The pica (P.) and the point (p.) are also among the units in the United States Customary Units, but they are rarely used.
Although technical and engineering drawings may use either measurement system (Metric System, or the United States Customary Units), they adhere to popularly accepted drawing standards.
The dimensions given in the United States Customary Units can be easily converted to Metric System units in decimal or fractional form. In standard practice, the following units and relationships are often used:
Just to mention a few, the importance of engineering graphics and design include (but are not limited to) the following:
Engineering graphics & design is important because it provides engineering and technology students with knowledge of techniques and standard practices generally employed worldwide in engineering graphics and design. This makes it easier or possible for design ideas to be adequately communicated, produced, and used in many countries.
Engineering graphics & design is important because it sharpens the imagination, and helps engineering professionals solve more advanced technological problems related to engineering graphics and design.
Uses/Applications of Engineering Graphics and Design
Although engineering graphics and design has many uses or applications, discussions will be limited to the following:
Engineering graphics and design can be used to produce “layout drawings” of completely designed end products; it can also be used in geometric studies to develop the movement of mechanical linkages, clearances, or arrangements.
Engineering graphics and design can be used to produce “mono-detail drawing” which is very important because it gives details and maximum clarity about any part of an engineering structure without having to view a whole structure.
Engineering graphics and design can be used to produce “assembly drawings” for 2-D projections that have to be joined together in order to form an “assembly” that gives a clear and precise overview of structures.
Engineering graphics and design can be used to produce “installation drawings” in order to provide technical information on how to properly position and install items. Installation drawings could include dimensional data, hardware descriptions, and information regarding general configuration on installation sites where control systems, electrical systems, hydraulic systems, and other types of systems exist.
Engineering graphics and design can be used to produce “modification drawings” in order to alter characteristics of items that have been purchased in bulk; examples include hinges, extrusions, channel nuts, semi-processed items as electronic equipment drawers, castings, blank panels, castings, etc. Drafts for altered items are usually prepared whenever it becomes necessary to alter existing items.
Engineering graphics and design can be used to produce “procurement control drawings” which provide criteria on performance, and identification of supplier items that list the engineering design characteristics required to ensure control of interfaces, and repeatability of performance according to design. In the commercial realm of engineering practice, procurement control drawings can be prepared for item identification, purchased items, alteration to purchased items, selection from purchased items, and development/qualification of new items.
Engineering graphics and design can be used to produce “mechanical systematic diagrams” whenever general operating principles cannot be promptly determined after studying assembly drawings. Generally, mechanical schematic diagrams clearly illustrate design information for hydraulic or pneumatic systems, and complex mechanical systems such as the complex arrangement of gears, cams, linkages, clutches, linkages, etc.
Engineering graphics and design can be used to produce “electrical & electronic diagrams” (in accordance with ANSI Y14.15 or ANSI/IEEE STD 991) in order to clearly describe the elements and functions of electrical or electronic tools/equipment in accordance with ANSI/IEEE STD 91 and 315.
Engineering graphics and design can be used to produce “functional block diagrams” in order to clearly illustrate the relationship between the functions of major elements in a system, or an assembly of various systems.
The eBook on “Technical Drawing with Engineering Graphics & Design in Practice: Definitions, Importance, and Applications”, which can be downloaded at the top of this page, discusses the following topics:
Definition of Engineering Graphics.
Definition of Graphical Engineering.
What Engineering Graphics and Design is all About
What is Engineering Design?
Application of Technical Drawing with Engineering Graphics in Engineering Design.
Basic Components of Engineering Graphics—the Code of Practice.
Importance of Engineering Graphics and Design.
Uses/Applications of Engineering Graphics and Design.
Thank you for reading.
Interested in buying world-class technical and engineering drawing eBooks? Please, read on.
Knowledge is power. The more you read, study, and absorb, the more you can greatly magnify your visualization process and become better. There is no limit.
For further reading and study of topics on technical and engineering drawings/graphics—which is essential for your education/future as an engineer/technologist and—we advise that you make a habit of reading good books.
It’s possible to get a good book from a friend or purchase it either from a local bookstore (offline) or online. In case you’d be interested in purchasing, we have six high-quality technical & engineering drawings/graphics books (eBooks/PDF books) for sale at cheap prices.
Continue scrolling down and you’ll come across their respective titles, number of pages, and lists of chapters. Each book is available for purchase at a cost of $5 (or 2,500 Naira) per book; if you wish to purchase all books, you’ll get a discount of $5 (2,500 Naira) and purchase 6 books for $25 (12,000 Naira) instead of $30 (15,000 Naira).
Note
For the past 3 years, until January 19, 2022, all the eBooks on this site were always available for free download (no payment). However, as from January 20, 2022, we introduced payments to be able to acquire, at least, little funds for the upkeep of our domain name and site maintenance for the benefit of present and future visitors who will read our articles on topics of their interest.
Instructions for payment
To purchase a copy or copies:
(1) Pay through any of the following 3 payment methods:
Send Bitcoin equivalent of USD to: 13jRM5DYmYSHvMraPB7c6JGhNk8dKzCVPg
Send Ethereum equivalent of USD to: 0xa571807E344D83797ebdFb01e3aFB3F7F43Da29B
Send USD ($) through WorldRemit, Remitly, or any other trustworthy platform/site to the following bank account:
Bank name: Guaranty Trust Bank (GTBank), Nigeria
Account name: Godwin Terhemba Ihagh
Account number: (Send Dollars to 0620810523; Naira to 0210490937)
Note: If you’d like to pay using a different payment option or another cryptocurrency that isn’t listed above, contact us through our email: godwinihagh@gmail.com or Whatsapp number: +2348033219907.
(2) After payment, take and send a screenshot(s) of the transaction(s) as evidence of payment to either our email: godwinihagh@gmail.com or Whatsapp number: +2348033219907.
(3) After confirming payment, we’ll provide you with access to the book(s) which is/are easy-to-read and contain(s) comprehensive coverage of technical and engineering drawing/drafting and design instructions that comply with present-day industry standards.
The titles of the books (arranged in decreasing order of priority [from 1 to 6]—based on our assessment) and their respective number of pages and titles of chapters are as follows:
1. Technical Graphics Communication, 4th Edition, by Gary R. Bertoline, Eric N. Wiebe, Nathan W. Hartman, William A. Ross (1335 pages), 2009
Chapter 1: Introduction to Graphics Communication, pg.5
Chapter 2: The Engineering Design Process, pg.27
Chapter 3: Design in Industry, pg.46
Chapter 4: The Role of Technical Graphics in Production, Automation, and Manufacturing Processes, pg.109
Chapter 5: Design & Visualization, pg.135
Chapter 6: Technical Drawing Tools, pg.187
Chapter 7: Sketching and Text, pg.237
Chapter 8: Engineering Geometry and Construction, pg.305
Chapter 9: Three-dimensional Modeling, pg.399
Chapter 10: Multiview Drawings, pg.488
Chapter 11: Axonometric and Oblique Drawings, pg.577
Chapter 12: Perspective Drawings, pg.631
Chapter 13: Auxiliary Views, pg.652
Chapter 14: Fundamentals of Descriptive Geometry, pg.691
Chapter 15: Intersections and Developments, pg.716
Chapter 16: Section Views, pg.759
Chapter 17: Dimensioning and Tolerancing Practices, pg.818
Chapter 18: Geometric Dimensioning and Tolerancing (GDT), pg.875
Chapter 19: Fastening Devices and Methods, pg.908
Chapter 20: Working Drawings, pg.949
Chapter 21: Technical Data Presentation, pg.1064
Chapter 22: Mechanisms: Gears, Cams, Bearings, and Linkages, pg.1105
Chapter 23: Electronic Drawings, pg.1146
Chapter 24: Piping Drawings, pg.1163
Chapter 25: Welding Drawings, pg.1187
2. Technical Drawing with Engineering Graphics, 15th Edition, by Frederick E. Giesecke, Shawna Lockhart, Marla Goodman, Cindy M. Johnson (1077 pages), 2016
Chapter 1: The World-wide Language for Graphic Design, pg.2
Chapter 2: Layouts and Lettering, pg.30
Chapter 3: Visualization and Sketching, pg.62
Chapter 4: Geometry for Modeling and Design, pg.124
Chapter 5: Modeling and Design, pg.170
Chapter 6: Orthographic Projection, pg.234
Chapter 7: 2D Drawing Representation, pg.284
Chapter 8: Section Views, pg.326
Chapter 9: Auxiliary Views, pg.362
Chapter 10: Modeling for Manufacture, pg.414
Chapter 11: Dimensioning, pg.502
Chapter 12: Tolerancing, pg.546
Chapter 13: Threads, Fasteners, and Springs, pg.592
Chapter 14: Working Drawings, pg.636
Chapter 15: Drawing Control and Data Management, pg.710
Chapter 16: Gears and Cams, pg.730
Chapter 17: Electronic Diagrams, pg.756
Chapter 18: Structural Drawing, pg.780
Chapter 19: Landform Drawings, pg.808
Chapter 20: Piping Drawings, pg.828
Chapter 21: Welding Representation, pg.846
Chapter 22: Axonometric Projection, pg.W870
Chapter 23: Perspective Drawings, pg.W900
3. Engineering Drawing & Design, 6th Edition, by David A. Madsen and David P. Madsen (1104 pages), 2017
Chapter 1: Introduction to Engineering Drawing and Design, pg.2
Chapter 2: Drafting Equipment, Media, and Reproduction Methods, pg.39
Chapter 3: Computer-Aided Design and Drafting (CADD), pg.61
Chapter 4: Manufacturing Materials and Processes, pg.109
Chapter 5: Sketching Applications, pg.162
Chapter 6: Lines and Lettering, pg.181
Chapter 7: Drafting Geometry, pg.205
Chapter 8: Multiviews, pg.228
Chapter 9: Auxiliary Views, pg.259
Chapter 10: Dimensioning and Tolerancing, pg.277
Chapter 11: Fasteners and Springs, pg. 347
Chapter 12: Sections, Revolutions, and Conventional Breaks, pg.387
Chapter 13: Geometric Dimensioning and Tolerancing, pg.409
Chapter 14: Pictorial Drawings and Technical Illustrations, pg.495
Chapter 15: Working Drawings, pg.526
Chapter 16: Mechanisms: Linkages, Cams, Gears, and Bearings, pg.561
Chapter 17: Belt and Chain Drives, pg.601
Chapter 18: Welding Processes and Representations, pg.617
Chapter 19: Precision Sheet Metal Drafting, pg.644
Chapter 20: Electrical and Electronic Drafting, pg.669
Chapter 21: Industrial Process Piping, pg.717
Chapter 22: Structural Drafting, pg.773
Chapter 23: Heating, Ventilating, and Air-conditioning (HVAC) and Pattern Development, pg.847
Chapter 24: Civil Drafting, pg.899
Chapter 25: The Engineering Design Process, pg.950
Engineering Drawing and Design Student Companion Website, pg.973
4. Engineering Design and Graphics with SolidWorks by James D. Bethune (829 pages), 2017
Chapter 1: Getting Started, pg.1
Chapter 2: Sketch Entities and Tools, pg.41
Chapter 3: Features, pg.123
Chapter 4: Orthographic Views, pg.225
Chapter 5: Assemblies, pg.299
Chapter 6: Threads and Fasteners, pg.375
Chapter 7: Dimensioning, pg.439
Chapter 8: Tolerancing, pg.509
Chapter 9: Bearings and Fit Tolerances, pg.605
Chapter 10: Gears, pg.639
Chapter 11: Belts and Pulleys, pg.699
Chapter 12: Cams, pg.725
Chapter 13: Projects, after pg.774
5. Interpreting Engineering Drawings, 8th Edition, by Theodore J. Branoff (530 pages), 2016
Unit 1: Introduction: Line Types and Sketching, pg.1
Unit 2: Lettering and Title Blocks, pg.11
Unit 3: Basic Geometry: Circles and Arcs, pg.15
Unit 4: Working Drawings and Projection Theory, pg.22
Unit 5: Introduction to Dimensioning, pg.39
Unit 6: Normal, Inclined, and Oblique Surfaces, pg.52
Unit 7: Pictorial Sketching, pg.67
Unit 8: Machining Symbols and Revision Blocks, pg.78
Unit 9: Chamfers, Undercuts, Tapers, and Knurls, pg.86
Unit 10: Sectional Views, pg.91
Unit 11: One- and Two-View Drawings, pg.110
Unit 12: Surface Texture, pg.117
Unit 13: Introduction to Conventional Tolerancing, pg.130
Unit 14: Inch Fits, pg.142
Unit 15: Metric Fits, pg.150
Unit 16: Threads and Fasteners, pg.161
Unit 17: Auxiliary Views, pg.181
Unit 18: Development Drawings, pg.190
Unit 19: Selection and Arrangement of Views, pg.196
Unit 20: Piping Drawings, pg.202
Unit 21: Bearings, pg.214
Unit 22: Manufacturing Materials, pg.220
Unit 23: Casting Processes, pg.232
Unit 24: Violating True Projection: Conventional Practices, pg.249
Unit 25: Pin Fasteners, pg.264
Unit 26: Drawings for Numerical Control, pg. 274
Unit 27: Assembly Drawings, pg.280
Unit 28: Structural Steel, pg.289
Unit 29: Welding Drawings, pg.294
Unit 30: Groove Welds, pg.305
Unit 31: Other Basic Welds, pg.315
Unit 32: Spur Gears, pg.328
Unit 33: Bevel Gears and Gear Trains, pg.337
Unit 34: Cams, pg.347
Unit 35: Bearings and Clutches, pg.353
Unit 36: Ratchet Wheels, pg.362
Unit 37: Introduction to Geometric Dimensioning and Tolerancing, pg.368
Unit 38: Features and Material Condition Modifiers, pg.380
Unit 39: Form Tolerances, pg.394
Unit 40: The Datum Reference Frame, pg.402
Unit 41: Orientation Tolerances, pg.415
Unit 42: Datum Targets, pg.432
Unit 43: Position Tolerances, pg.440
Unit 44: Profile Tolerances, pg.461
Unit 45: Runout Tolerances, pg.469
6. Architectural Graphic Standards Student Edition, 12th Edition, by The American Institute of Architects (689 pages), 2017
Chapter 1: Functional Planning, pg.3
Chapter 2: Environment, pg.31
Chapter 3: Resilience in Buildings. Pg.53
Chapter 4: Architectural Construction Documentation, pg.77
Chapter 5: Concrete, pg.93
Chapter 6: Masonry, pg.107
Chapter 7: Metals, pg.125
Chapter 8: Wood, pg.141
Chapter 9: Glass, pg.165
Chapter 10: Element A: Substructure, pg.176
Chapter 11: Element B: Shell, pg.203
Chapter 12: Element C: Interiors, pg.363
Chapter 13: Element D: Services, pg.427
Chapter 14: Element E: Equipment and Furnishings, pg.517
Chapter 15: Element F: Special Construction, pg.565
Interested in buying world-class technical and engineering drawing eBooks? Please, read on.
Knowledge is power. The more you read, study, and absorb, the more you can greatly magnify your visualization process and become better. There is no limit.
For further reading and study of topics on technical and engineering drawings/graphics—which is essential for your education/future as an engineer/technologist and—we advise that you make a habit of reading good books.
It’s possible to get a good book from a friend or purchase it either from a local bookstore (offline) or online. In case you’d be interested in purchasing, we have six high-quality technical & engineering drawings/graphics books (eBooks/PDF books) for sale at cheap prices.
Continue scrolling down and you’ll come across their respective titles, number of pages, and lists of chapters. Each book is available for purchase at a cost of $5 (or 2,500 Naira) per book; if you wish to purchase all books, you’ll get a discount of $5 (2,500 Naira) and purchase 6 books for $25 (12,000 Naira) instead of $30 (15,000 Naira).
Note
For the past 3 years, until January 19, 2022, all the eBooks on this site were always available for free download (no payment). However, as from January 20, 2022, we introduced payments to be able to acquire, at least, little funds for the upkeep of our domain name and site maintenance for the benefit of present and future visitors who will read our articles on topics of their interest.
Instructions for payment
To purchase a copy or copies:
(1) Pay through any of the following 3 payment methods:
Send Bitcoin equivalent of USD to: 13jRM5DYmYSHvMraPB7c6JGhNk8dKzCVPg
Send Ethereum equivalent of USD to: 0xa571807E344D83797ebdFb01e3aFB3F7F43Da29B
Send USD ($) through WorldRemit, Remitly, or any other trustworthy platform/site to the following bank account:
Bank name: Guaranty Trust Bank (GTBank), Nigeria
Account name: Godwin Terhemba Ihagh
Account number: (Send Dollars to 0620810523; Naira to 0210490937)
Note: If you’d like to pay using a different payment option or another cryptocurrency that isn’t listed above, contact us through our email: godwinihagh@gmail.com or Whatsapp number: +2348033219907.
(2) After payment, take and send a screenshot(s) of the transaction(s) as evidence of payment to either our email: godwinihagh@gmail.com or Whatsapp number: +2348033219907.
(3) After confirming payment, we’ll provide you with access to the book(s) which is/are easy-to-read and contain(s) comprehensive coverage of technical and engineering drawing/drafting and design instructions that comply with present-day industry standards.
The titles of the books (arranged in decreasing order of priority [from 1 to 6]—based on our assessment) and their respective number of pages and titles of chapters are as follows:
1. Technical Graphics Communication, 4th Edition, by Gary R. Bertoline, Eric N. Wiebe, Nathan W. Hartman, William A. Ross (1335 pages), 2009
Chapter 1: Introduction to Graphics Communication, pg.5
Chapter 2: The Engineering Design Process, pg.27
Chapter 3: Design in Industry, pg.46
Chapter 4: The Role of Technical Graphics in Production, Automation, and Manufacturing Processes, pg.109
Chapter 5: Design & Visualization, pg.135
Chapter 6: Technical Drawing Tools, pg.187
Chapter 7: Sketching and Text, pg.237
Chapter 8: Engineering Geometry and Construction, pg.305
Chapter 9: Three-dimensional Modeling, pg.399
Chapter 10: Multiview Drawings, pg.488
Chapter 11: Axonometric and Oblique Drawings, pg.577
Chapter 12: Perspective Drawings, pg.631
Chapter 13: Auxiliary Views, pg.652
Chapter 14: Fundamentals of Descriptive Geometry, pg.691
Chapter 15: Intersections and Developments, pg.716
Chapter 16: Section Views, pg.759
Chapter 17: Dimensioning and Tolerancing Practices, pg.818
Chapter 18: Geometric Dimensioning and Tolerancing (GDT), pg.875
Chapter 19: Fastening Devices and Methods, pg.908
Chapter 20: Working Drawings, pg.949
Chapter 21: Technical Data Presentation, pg.1064
Chapter 22: Mechanisms: Gears, Cams, Bearings, and Linkages, pg.1105
Chapter 23: Electronic Drawings, pg.1146
Chapter 24: Piping Drawings, pg.1163
Chapter 25: Welding Drawings, pg.1187
2. Technical Drawing with Engineering Graphics, 15th Edition, by Frederick E. Giesecke, Shawna Lockhart, Marla Goodman, Cindy M. Johnson (1077 pages), 2016
Chapter 1: The World-wide Language for Graphic Design, pg.2
Chapter 2: Layouts and Lettering, pg.30
Chapter 3: Visualization and Sketching, pg.62
Chapter 4: Geometry for Modeling and Design, pg.124
Chapter 5: Modeling and Design, pg.170
Chapter 6: Orthographic Projection, pg.234
Chapter 7: 2D Drawing Representation, pg.284
Chapter 8: Section Views, pg.326
Chapter 9: Auxiliary Views, pg.362
Chapter 10: Modeling for Manufacture, pg.414
Chapter 11: Dimensioning, pg.502
Chapter 12: Tolerancing, pg.546
Chapter 13: Threads, Fasteners, and Springs, pg.592
Chapter 14: Working Drawings, pg.636
Chapter 15: Drawing Control and Data Management, pg.710
Chapter 16: Gears and Cams, pg.730
Chapter 17: Electronic Diagrams, pg.756
Chapter 18: Structural Drawing, pg.780
Chapter 19: Landform Drawings, pg.808
Chapter 20: Piping Drawings, pg.828
Chapter 21: Welding Representation, pg.846
Chapter 22: Axonometric Projection, pg.W870
Chapter 23: Perspective Drawings, pg.W900
3. Engineering Drawing & Design, 6th Edition, by David A. Madsen and David P. Madsen (1104 pages), 2017
Chapter 1: Introduction to Engineering Drawing and Design, pg.2
Chapter 2: Drafting Equipment, Media, and Reproduction Methods, pg.39
Chapter 3: Computer-Aided Design and Drafting (CADD), pg.61
Chapter 4: Manufacturing Materials and Processes, pg.109
Chapter 5: Sketching Applications, pg.162
Chapter 6: Lines and Lettering, pg.181
Chapter 7: Drafting Geometry, pg.205
Chapter 8: Multiviews, pg.228
Chapter 9: Auxiliary Views, pg.259
Chapter 10: Dimensioning and Tolerancing, pg.277
Chapter 11: Fasteners and Springs, pg. 347
Chapter 12: Sections, Revolutions, and Conventional Breaks, pg.387
Chapter 13: Geometric Dimensioning and Tolerancing, pg.409
Chapter 14: Pictorial Drawings and Technical Illustrations, pg.495
Chapter 15: Working Drawings, pg.526
Chapter 16: Mechanisms: Linkages, Cams, Gears, and Bearings, pg.561
Chapter 17: Belt and Chain Drives, pg.601
Chapter 18: Welding Processes and Representations, pg.617
Chapter 19: Precision Sheet Metal Drafting, pg.644
Chapter 20: Electrical and Electronic Drafting, pg.669
Chapter 21: Industrial Process Piping, pg.717
Chapter 22: Structural Drafting, pg.773
Chapter 23: Heating, Ventilating, and Air-conditioning (HVAC) and Pattern Development, pg.847
Chapter 24: Civil Drafting, pg.899
Chapter 25: The Engineering Design Process, pg.950
Engineering Drawing and Design Student Companion Website, pg.973
4. Engineering Design and Graphics with SolidWorks by James D. Bethune (829 pages), 2017
Chapter 1: Getting Started, pg.1
Chapter 2: Sketch Entities and Tools, pg.41
Chapter 3: Features, pg.123
Chapter 4: Orthographic Views, pg.225
Chapter 5: Assemblies, pg.299
Chapter 6: Threads and Fasteners, pg.375
Chapter 7: Dimensioning, pg.439
Chapter 8: Tolerancing, pg.509
Chapter 9: Bearings and Fit Tolerances, pg.605
Chapter 10: Gears, pg.639
Chapter 11: Belts and Pulleys, pg.699
Chapter 12: Cams, pg.725
Chapter 13: Projects, after pg.774
5. Interpreting Engineering Drawings, 8th Edition, by Theodore J. Branoff (530 pages), 2016
Unit 1: Introduction: Line Types and Sketching, pg.1
Unit 2: Lettering and Title Blocks, pg.11
Unit 3: Basic Geometry: Circles and Arcs, pg.15
Unit 4: Working Drawings and Projection Theory, pg.22
Unit 5: Introduction to Dimensioning, pg.39
Unit 6: Normal, Inclined, and Oblique Surfaces, pg.52
Unit 7: Pictorial Sketching, pg.67
Unit 8: Machining Symbols and Revision Blocks, pg.78
Unit 9: Chamfers, Undercuts, Tapers, and Knurls, pg.86
Unit 10: Sectional Views, pg.91
Unit 11: One- and Two-View Drawings, pg.110
Unit 12: Surface Texture, pg.117
Unit 13: Introduction to Conventional Tolerancing, pg.130
Unit 14: Inch Fits, pg.142
Unit 15: Metric Fits, pg.150
Unit 16: Threads and Fasteners, pg.161
Unit 17: Auxiliary Views, pg.181
Unit 18: Development Drawings, pg.190
Unit 19: Selection and Arrangement of Views, pg.196
Unit 20: Piping Drawings, pg.202
Unit 21: Bearings, pg.214
Unit 22: Manufacturing Materials, pg.220
Unit 23: Casting Processes, pg.232
Unit 24: Violating True Projection: Conventional Practices, pg.249
Unit 25: Pin Fasteners, pg.264
Unit 26: Drawings for Numerical Control, pg. 274
Unit 27: Assembly Drawings, pg.280
Unit 28: Structural Steel, pg.289
Unit 29: Welding Drawings, pg.294
Unit 30: Groove Welds, pg.305
Unit 31: Other Basic Welds, pg.315
Unit 32: Spur Gears, pg.328
Unit 33: Bevel Gears and Gear Trains, pg.337
Unit 34: Cams, pg.347
Unit 35: Bearings and Clutches, pg.353
Unit 36: Ratchet Wheels, pg.362
Unit 37: Introduction to Geometric Dimensioning and Tolerancing, pg.368
Unit 38: Features and Material Condition Modifiers, pg.380
Unit 39: Form Tolerances, pg.394
Unit 40: The Datum Reference Frame, pg.402
Unit 41: Orientation Tolerances, pg.415
Unit 42: Datum Targets, pg.432
Unit 43: Position Tolerances, pg.440
Unit 44: Profile Tolerances, pg.461
Unit 45: Runout Tolerances, pg.469
6. Architectural Graphic Standards Student Edition, 12th Edition, by The American Institute of Architects (689 pages), 2017
Chapter 1: Functional Planning, pg.3
Chapter 2: Environment, pg.31
Chapter 3: Resilience in Buildings. Pg.53
Chapter 4: Architectural Construction Documentation, pg.77
Chapter 5: Concrete, pg.93
Chapter 6: Masonry, pg.107
Chapter 7: Metals, pg.125
Chapter 8: Wood, pg.141
Chapter 9: Glass, pg.165
Chapter 10: Element A: Substructure, pg.176
Chapter 11: Element B: Shell, pg.203
Chapter 12: Element C: Interiors, pg.363
Chapter 13: Element D: Services, pg.427
Chapter 14: Element E: Equipment and Furnishings, pg.517
Chapter 15: Element F: Special Construction, pg.565
Drawing is a universal language that human beings have been using to express the visual images they conceive in their minds; it is such an old practice that its recorded history could be as old as humanity.
There is evidence that as far back as 12,000 B.C., ancient caves were inscribed with drawings that give clues to some human experiences in prehistoric times.
Technical & engineering drawings—or drawings that communicate technical ideas—might have even existed before written language. There is evidence that what we now call “technical planning” in the present-day, actually started about 7,000 B.C.
As ancient and earlier societies became more civilized and advanced, they planned and organized how roads, cities, bridges, and other structures would be built; technical drawing was the most important tool to achieve this goal, especially in the fields of engineering and architecture which are deeply ingrained in society.
At inception, technical drawings were drawn with hands by using tools that can be regarded as primitive versions of the present-day manual (traditional) technical & engineering drawing tools: set square, ruler, protractor, and compass; it would remain this way for about 5,000 years before the beginning of engineering and architectural drawing/drafting.
The earliest form of modern-day drawing instruments can be found in the Museum of the Louvre, Paris, on two headless statues of Gudea (2,130 B.C.).
In ancient times, Gudea was an engineer and the governor of the city/state of Lagash which was located in the country later known as Babylon. Two contemporary drawing boards were also constructed and placed on the statues of Gudea.
The drawing boards had the top (plan) view of the temple of Ningirsu, and another drawing tool that looked like a scribing instrument and scales.
The ancient Greek civilization has had a great deal of influence on modern-day drawing through its work in geometry. Many of the manual tools used in technical & engineering drawings, such as the compass and triangles, were developed when Greek civilization was at its peak.
Around the year 450 B.C., the architects of the Parthenon, Ictinus, and Callicrates used perspective drawing by foreshortening and converging parallel lines in their technical drawings.
At different points throughout history, great civilizations across the world (Africa, Europe, Asia, Middle East, South America, North America) adopted one form of technical drawing or another.
Brief history of non-mathematical and mathematical approaches to technical & engineering drawings
During the renaissance (mainly between the 14th and 17th centuries), two popular approaches to drawing were developed at the time: the non-mathematical, and the mathematical approaches.
Giotto and Duccio used the non-mathematical approach to advance the applicability of perspective drawings by using symmetry, converging lines, and the technique of foreshortening.
On the other hand, Italian architect, Brunelleschi, used the mathematical approach and its terms to demonstrate the theoretical principles of perspective drawing. The era of Brunelleschi was followed by that of Alberti who mathematically defined the principles of perspective drawing in paintings.
Other people who advanced the mathematical approach were Francesca (who made 3-view drawings using orthogonal projection), Leonardo da Vinci (who wrote about the theory of perspective drawings), and Durer (who published a book on orthographic drawing). In the early 19th century, William Farish introduced isometric drawing as a type of pictorial drawing.
During the evolution of technical & engineering drawing, one thing is quite clear: in ancient times, it was difficult for human beings to express or illustrate 3D (three-dimensional) objects on 2D (two-dimensional) surfaces.
Brief history of the science of technical & engineering drawings known as “descriptive geometry”
A young and exceptional mathematician named Gaspard Monge developed the science of technical drawing known as descriptive geometry while designing a complicated star-shaped fortress. He used orthographic drawing to solve some problems graphically, instead of mathematically.
The great contributions of Gaspard Monge are the basis of today’s three-dimensional representations on two-dimensional media such a paper and computer screen.
Brief history of the computer graphics (CAD) form of technical & engineering drawings
Computers have had a significant impact on the types of projections used to design and produce technical & engineering drawings. In 1950, the first computer-driven display attached to MIT’s Whirlwind I computer was used to produce simple pictures; advances in computer graphics increased significantly from that time onwards.
An MIT graduate student named Ivan Sutherland published his doctoral thesis in 1963 and paved a way for the development of interactive computer graphics which later evolved into computer-aided design (CAD). In the middle of the 1960s, many studies were conducted in the field of computer graphics at MIT, Bell Telephone laboratories, GM, and Lockheed Aircraft.
Developments continued through the 1970s, and around 1980 IBM and Apple popularized the use of bitmap graphics which led to the widespread use of inexpensive graphics-based applications.
In the early 1980s, computer-based software programs began to emerge, with AutoCAD and Versa CAD being the most popularly used at the time. From the 1990s till date, the world has witnessed the growth of CAD companies and 3D modeling which supports the design of objects, products, and structures.
Interested in buying world-class technical and engineering drawing eBooks? Please, read on.
Knowledge is power. The more you read, study, and absorb, the more you can greatly magnify your visualization process and become better. There is no limit.
For further reading and study of topics on technical and engineering drawings/graphics—which is essential for your education/future as an engineer/technologist and—we advise that you make a habit of reading good books.
It’s possible to get a good book from a friend or purchase it either from a local bookstore (offline) or online. In case you’d be interested in purchasing, we have six high-quality technical & engineering drawings/graphics books (eBooks/PDF books) for sale at cheap prices.
Continue scrolling down and you’ll come across their respective titles, number of pages, and lists of chapters. Each book is available for purchase at a cost of $5 (or 2,500 Naira) per book; if you wish to purchase all books, you’ll get a discount of $5 (2,500 Naira) and purchase 6 books for $25 (12,000 Naira) instead of $30 (15,000 Naira).
Note
For the past 3 years, until January 19, 2022, all the eBooks on this site were always available for free download (no payment). However, as from January 20, 2022, we introduced payments to be able to acquire, at least, little funds for the upkeep of our domain name and site maintenance for the benefit of present and future visitors who will read our articles on topics of their interest.
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(2) After payment, take and send a screenshot(s) of the transaction(s) as evidence of payment to either our email: godwinihagh@gmail.com or Whatsapp number: +2348033219907.
(3) After confirming payment, we’ll provide you with access to the book(s) which is/are easy-to-read and contain(s) comprehensive coverage of technical and engineering drawing/drafting and design instructions that comply with present-day industry standards.
The titles of the books (arranged in decreasing order of priority [from 1 to 6]—based on our assessment) and their respective number of pages and titles of chapters are as follows:
1. Technical Graphics Communication, 4th Edition, by Gary R. Bertoline, Eric N. Wiebe, Nathan W. Hartman, William A. Ross (1335 pages), 2009
Chapter 1: Introduction to Graphics Communication, pg.5
Chapter 2: The Engineering Design Process, pg.27
Chapter 3: Design in Industry, pg.46
Chapter 4: The Role of Technical Graphics in Production, Automation, and Manufacturing Processes, pg.109
Chapter 5: Design & Visualization, pg.135
Chapter 6: Technical Drawing Tools, pg.187
Chapter 7: Sketching and Text, pg.237
Chapter 8: Engineering Geometry and Construction, pg.305
Chapter 9: Three-dimensional Modeling, pg.399
Chapter 10: Multiview Drawings, pg.488
Chapter 11: Axonometric and Oblique Drawings, pg.577
Chapter 12: Perspective Drawings, pg.631
Chapter 13: Auxiliary Views, pg.652
Chapter 14: Fundamentals of Descriptive Geometry, pg.691
Chapter 15: Intersections and Developments, pg.716
Chapter 16: Section Views, pg.759
Chapter 17: Dimensioning and Tolerancing Practices, pg.818
Chapter 18: Geometric Dimensioning and Tolerancing (GDT), pg.875
Chapter 19: Fastening Devices and Methods, pg.908
Chapter 20: Working Drawings, pg.949
Chapter 21: Technical Data Presentation, pg.1064
Chapter 22: Mechanisms: Gears, Cams, Bearings, and Linkages, pg.1105
Chapter 23: Electronic Drawings, pg.1146
Chapter 24: Piping Drawings, pg.1163
Chapter 25: Welding Drawings, pg.1187
2. Technical Drawing with Engineering Graphics, 15th Edition, by Frederick E. Giesecke, Shawna Lockhart, Marla Goodman, Cindy M. Johnson (1077 pages), 2016
Chapter 1: The World-wide Language for Graphic Design, pg.2
Chapter 2: Layouts and Lettering, pg.30
Chapter 3: Visualization and Sketching, pg.62
Chapter 4: Geometry for Modeling and Design, pg.124
Chapter 5: Modeling and Design, pg.170
Chapter 6: Orthographic Projection, pg.234
Chapter 7: 2D Drawing Representation, pg.284
Chapter 8: Section Views, pg.326
Chapter 9: Auxiliary Views, pg.362
Chapter 10: Modeling for Manufacture, pg.414
Chapter 11: Dimensioning, pg.502
Chapter 12: Tolerancing, pg.546
Chapter 13: Threads, Fasteners, and Springs, pg.592
Chapter 14: Working Drawings, pg.636
Chapter 15: Drawing Control and Data Management, pg.710
Chapter 16: Gears and Cams, pg.730
Chapter 17: Electronic Diagrams, pg.756
Chapter 18: Structural Drawing, pg.780
Chapter 19: Landform Drawings, pg.808
Chapter 20: Piping Drawings, pg.828
Chapter 21: Welding Representation, pg.846
Chapter 22: Axonometric Projection, pg.W870
Chapter 23: Perspective Drawings, pg.W900
3. Engineering Drawing & Design, 6th Edition, by David A. Madsen and David P. Madsen (1104 pages), 2017
Chapter 1: Introduction to Engineering Drawing and Design, pg.2
Chapter 2: Drafting Equipment, Media, and Reproduction Methods, pg.39
Chapter 3: Computer-Aided Design and Drafting (CADD), pg.61
Chapter 4: Manufacturing Materials and Processes, pg.109
Chapter 5: Sketching Applications, pg.162
Chapter 6: Lines and Lettering, pg.181
Chapter 7: Drafting Geometry, pg.205
Chapter 8: Multiviews, pg.228
Chapter 9: Auxiliary Views, pg.259
Chapter 10: Dimensioning and Tolerancing, pg.277
Chapter 11: Fasteners and Springs, pg. 347
Chapter 12: Sections, Revolutions, and Conventional Breaks, pg.387
Chapter 13: Geometric Dimensioning and Tolerancing, pg.409
Chapter 14: Pictorial Drawings and Technical Illustrations, pg.495
Chapter 15: Working Drawings, pg.526
Chapter 16: Mechanisms: Linkages, Cams, Gears, and Bearings, pg.561
Chapter 17: Belt and Chain Drives, pg.601
Chapter 18: Welding Processes and Representations, pg.617
Chapter 19: Precision Sheet Metal Drafting, pg.644
Chapter 20: Electrical and Electronic Drafting, pg.669
Chapter 21: Industrial Process Piping, pg.717
Chapter 22: Structural Drafting, pg.773
Chapter 23: Heating, Ventilating, and Air-conditioning (HVAC) and Pattern Development, pg.847
Chapter 24: Civil Drafting, pg.899
Chapter 25: The Engineering Design Process, pg.950
Engineering Drawing and Design Student Companion Website, pg.973
4. Engineering Design and Graphics with SolidWorks by James D. Bethune (829 pages), 2017
Chapter 1: Getting Started, pg.1
Chapter 2: Sketch Entities and Tools, pg.41
Chapter 3: Features, pg.123
Chapter 4: Orthographic Views, pg.225
Chapter 5: Assemblies, pg.299
Chapter 6: Threads and Fasteners, pg.375
Chapter 7: Dimensioning, pg.439
Chapter 8: Tolerancing, pg.509
Chapter 9: Bearings and Fit Tolerances, pg.605
Chapter 10: Gears, pg.639
Chapter 11: Belts and Pulleys, pg.699
Chapter 12: Cams, pg.725
Chapter 13: Projects, after pg.774
5. Interpreting Engineering Drawings, 8th Edition, by Theodore J. Branoff (530 pages), 2016
Unit 1: Introduction: Line Types and Sketching, pg.1
Unit 2: Lettering and Title Blocks, pg.11
Unit 3: Basic Geometry: Circles and Arcs, pg.15
Unit 4: Working Drawings and Projection Theory, pg.22
Unit 5: Introduction to Dimensioning, pg.39
Unit 6: Normal, Inclined, and Oblique Surfaces, pg.52
Unit 7: Pictorial Sketching, pg.67
Unit 8: Machining Symbols and Revision Blocks, pg.78
Unit 9: Chamfers, Undercuts, Tapers, and Knurls, pg.86
Unit 10: Sectional Views, pg.91
Unit 11: One- and Two-View Drawings, pg.110
Unit 12: Surface Texture, pg.117
Unit 13: Introduction to Conventional Tolerancing, pg.130
Unit 14: Inch Fits, pg.142
Unit 15: Metric Fits, pg.150
Unit 16: Threads and Fasteners, pg.161
Unit 17: Auxiliary Views, pg.181
Unit 18: Development Drawings, pg.190
Unit 19: Selection and Arrangement of Views, pg.196
Unit 20: Piping Drawings, pg.202
Unit 21: Bearings, pg.214
Unit 22: Manufacturing Materials, pg.220
Unit 23: Casting Processes, pg.232
Unit 24: Violating True Projection: Conventional Practices, pg.249
Unit 25: Pin Fasteners, pg.264
Unit 26: Drawings for Numerical Control, pg. 274
Unit 27: Assembly Drawings, pg.280
Unit 28: Structural Steel, pg.289
Unit 29: Welding Drawings, pg.294
Unit 30: Groove Welds, pg.305
Unit 31: Other Basic Welds, pg.315
Unit 32: Spur Gears, pg.328
Unit 33: Bevel Gears and Gear Trains, pg.337
Unit 34: Cams, pg.347
Unit 35: Bearings and Clutches, pg.353
Unit 36: Ratchet Wheels, pg.362
Unit 37: Introduction to Geometric Dimensioning and Tolerancing, pg.368
Unit 38: Features and Material Condition Modifiers, pg.380
Unit 39: Form Tolerances, pg.394
Unit 40: The Datum Reference Frame, pg.402
Unit 41: Orientation Tolerances, pg.415
Unit 42: Datum Targets, pg.432
Unit 43: Position Tolerances, pg.440
Unit 44: Profile Tolerances, pg.461
Unit 45: Runout Tolerances, pg.469
6. Architectural Graphic Standards Student Edition, 12th Edition, by The American Institute of Architects (689 pages), 2017
Chapter 1: Functional Planning, pg.3
Chapter 2: Environment, pg.31
Chapter 3: Resilience in Buildings. Pg.53
Chapter 4: Architectural Construction Documentation, pg.77
Chapter 5: Concrete, pg.93
Chapter 6: Masonry, pg.107
Chapter 7: Metals, pg.125
Chapter 8: Wood, pg.141
Chapter 9: Glass, pg.165
Chapter 10: Element A: Substructure, pg.176
Chapter 11: Element B: Shell, pg.203
Chapter 12: Element C: Interiors, pg.363
Chapter 13: Element D: Services, pg.427
Chapter 14: Element E: Equipment and Furnishings, pg.517
Chapter 15: Element F: Special Construction, pg.565
Technical & engineering drawings are real clear-cut languages used in the technical and engineering design processes for visualization, communication, and documentation; these are areas where technical & engineering drawings are very important.
As you may know, drawings are graphical representations of objects, shapes, and structures that are drawn using either freehand, mechanical, or computer methods.
Generally speaking, any technical or engineering drawing serves as a graphic model or representation of a real object or an idea that existed originally in the mind. Drawings could be abstract, such as the multi-view drawings shown in the figure below.
Figure 1: Multi-view drawing of a journal bearing which is actually a shaft or journal that rotates in a bearing
On the other hand, drawings could be more concrete, such as the computer model shown in the figure below.
Figure 2: A 3-D computer model of the inner part of an automobile
Only knowledgeable and experienced practitioners of technical & engineering drawings can sufficiently interpret the types of lines, know the exact shapes of objects (rectangles, squares, circles, etc.) in figure 1, and have a clear mental picture of how objects would appear in three-dimension (3D).
The 3-D computer model in figure 2 can be more easily interpreted and understood because its drawing or graphical details are expressed with different types of lights, colors, shades, and shadows.
The projection techniques shown in figures 1 and 2 (in 2D and 3D; on paper and computer screens) took probably a hundred years or more to develop. Actually, it has taken millennia for the techniques of technical & engineering drawing to evolve into what we use today.
We will take a brief look at the importance of technical & engineering drawing in the following areas:
Visualization
Communication
Documentation
Technical & engineering drawings help in visualization, and problem-solving
Technical & engineering drawing is a powerful tool that designers use to enhance their ability to develop greater ideas in the mind and solve problems. As you may have known, visualization is the ability to produce mental pictures (in the mind) of things that either exist or don’t exist.
Great designers like Leonardo da Vinci, and Jules Verne had excellent visualization skills that produced countless pictures of objects in their minds, and representations of how they would appear if they were/are moved around mentally—as if hands were used to move the objects around.
Everything in life—computers, cars, great pyramids, rockets, etc.—initially existed, not because of their shape or geometry, but because they were first thought about, pictured, or conceived in the minds of the people who finally constructed or produced them.
Most designers initially get ideas in the mind and sketch them on paper. Sometimes sketches are rough when initially drawn; at later stages, sketches are refined with a more professional tone, and into a more professional drawing.
Technical & engineering drawings make communication easy during design processes
Technical & engineering drawing is important because it aids communication and easy passage of ideas from one person to another, especially when it’s done without ambiguity and to such an extent that other people can be able to visualize and understand or interpret any design that embraces the basic components and code of practice of technical & engineering drawing.
Imagine how beautiful and clear final designs appear after technical drawing and 3D CAD modeling are used to clarify and refine sketches that were initially drawn as rough ideas from the mind.
Technical & engineering drawings help in documentation
Besides being useful in visualizing ideas and communicating effectively, technical & engineering drawing is important for documentation; and also for both legal and archival purposes. Documentation of drawings is always important for the present and future needs so that anyone who comes across such drawing documents may benefit from it in one way or another.
The types and uses of various types of lines in technical & engineering drawing are as follows: (Note: Two diagrams at the end of this page illustrate how the various types of lines appear in drawings.)
Break lines
Break lines are used to create breakouts on sections in order to shorten distances between parts of a drawing and give more clarity. Three types of lines are normally used as break lines; they have different line weights: long break lines, short break lines, cylindrical break lines.
Center Lines (or, long/short-dashed thin lines)
Center lines are used to locate or represent the centers of tools, circles, cylindrical surfaces or volumes, and symmetrical areas/objects, etc. Center lines are drawn as thin broken lines that have long and short dashes. In many instances, the long and short dashes vary in length; however, this depends on the scale or size of the drawing. Center lines could be extended and used as extension lines during dimensioning of objects or shapes.
Chain lines
Chain lines are broken or spaced parallel lines used to indicate either pitch lines (lines that show the pitch of gear teeth or sprocket teeth), center lines, developed views, or the features in front of a cutting plane. Usually, chain lines are applied at the beginning and end of long dashes, at center points as center lines, in dimensioning, or for other purposes.
Construction Lines
Construction lines (light thin lines) are used to develop shapes and locations of features in technical & engineering drawings. After using construction lines to develop thick visible outlines of objects, they are either left on the sketches of many drawings, or cleaned off with an eraser.
Continuous thick lines
Continuous thick lines are used to represent visible edges and outlines of objects, shapes, and structures on paper or computer. They are usually dark and heavy solid lines which are very prominent in many drawings.
Continuous thin lines
Continuous thin lines are used to represent dimension lines, extension lines, projection lines, hatching lines for cross sections, leader lines, reference lines, imaginary lines of intersections, and short center lines.
Cutting plane lines (viewing plane lines)
Cutting plane lines are used to indicate the positions of cutting planes in sections, or during sectioning. Two types of cutting plane lines can be used.
The first type is a dark line that consists of one long dash and two short dashes spaced alternately. Long dashes are usually drawn at any length between 20 and 40mm, or a little bit more; it depends on the scale and size of the drawing. On the other hand, short dashes are usually drawn approximately 3mm long, and spaced at 1.5mm (between dashes).
The second type of cutting plane line consists of short dashes of equal lengths, approximately 6mm long, with a space (of length) of 1.5mm between each short dash.
Dimension lines
Dimension lines are thin lines that have arrowheads at their opposite ends; they are used to show the precise length, breadth, width, and height of objects.
Extension lines are thin solid lines that are used to show the extent (beginning and end) of a dimension in a drawing. Extension lines are usually drawn at approximately 1.5mm away from the outlines of objects and extended 3mm longer than the outermost arrowheads located at the ends of dimension lines.
Freehand break lines are lines drawn with freehand, and used to indicate short-breaks or irregular boundaries; they can be used to set the limits of partial views or sections.
Hatching lines (or section lines)
Hatching or section lines are used to indicate the sectional view or outlook of surfaces produced as a result of making arbitrary cuts on an object. Hatching lines are usually thin lines that are drawn at an angle of 45° and equally spaced.
Hidden Lines
Hidden lines are used to describe features that cannot be seen when objects are viewed from a particular direction; they consist of short and equally spaced thin dash lines and spaces. The dashes are usually three to four times longer than the space between them.
It is recommended that the dashes used in hidden lines should be approximately 3 mm long, and have a space of 1.0mm between each dash. On the other hand, the length of the dashes, and the space between them can be slightly altered, depending on the scale and size of the drawing.
Leader lines
Leader lines are used to show the dimensions of an object, feature, or structure whenever such dimensions are not clear enough after being placed beside objects, features, or drawn structures.
Long Break line (or continuous thin straight lines with zigzags)
Long break lines (or continuous straight lines with zigzags) show continuity of partially interrupted views; they are very suitable for computer-aided design (CAD) drawings.
Symmetry Lines
Symmetry lines are imaginary lines that pass through the centers of areas, shapes, objects, and drawn structures; in most cases, symmetry lines divide objects into equal and similar-looking parts.
Visible Lines
Visible lines are thick and continuous bold lines that are used to indicate the visible edges of objects. They usually stand out when compared with other lines.
The figures below are pictorial views of various types of lines used in technical & engineering drawing:
Figure 1: A drawing that shows various types of lines
Figure 2: A drawing that shows various types of lines
Thank you for reading.
Interested in buying world-class technical and engineering drawing eBooks? Please, read on.
Knowledge is power. The more you read, study, and absorb, the more you can greatly magnify your visualization process and become better. There is no limit.
For further reading and study of topics on technical and engineering drawings/graphics—which is essential for your education/future as an engineer/technologist and—we advise that you make a habit of reading good books.
It’s possible to get a good book from a friend or purchase it either from a local bookstore (offline) or online. In case you’d be interested in purchasing, we have six high-quality technical & engineering drawings/graphics books (eBooks/PDF books) for sale at cheap prices.
Continue scrolling down and you’ll come across their respective titles, number of pages, and lists of chapters. Each book is available for purchase at a cost of $5 (or 2,500 Naira) per book; if you wish to purchase all books, you’ll get a discount of $5 (2,500 Naira) and purchase 6 books for $25 (12,000 Naira) instead of $30 (15,000 Naira).
Note
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The titles of the books (arranged in decreasing order of priority [from 1 to 6]—based on our assessment) and their respective number of pages and titles of chapters are as follows:
1. Technical Graphics Communication, 4th Edition, by Gary R. Bertoline, Eric N. Wiebe, Nathan W. Hartman, William A. Ross (1335 pages), 2009
Chapter 1: Introduction to Graphics Communication, pg.5
Chapter 2: The Engineering Design Process, pg.27
Chapter 3: Design in Industry, pg.46
Chapter 4: The Role of Technical Graphics in Production, Automation, and Manufacturing Processes, pg.109
Chapter 5: Design & Visualization, pg.135
Chapter 6: Technical Drawing Tools, pg.187
Chapter 7: Sketching and Text, pg.237
Chapter 8: Engineering Geometry and Construction, pg.305
Chapter 9: Three-dimensional Modeling, pg.399
Chapter 10: Multiview Drawings, pg.488
Chapter 11: Axonometric and Oblique Drawings, pg.577
Chapter 12: Perspective Drawings, pg.631
Chapter 13: Auxiliary Views, pg.652
Chapter 14: Fundamentals of Descriptive Geometry, pg.691
Chapter 15: Intersections and Developments, pg.716
Chapter 16: Section Views, pg.759
Chapter 17: Dimensioning and Tolerancing Practices, pg.818
Chapter 18: Geometric Dimensioning and Tolerancing (GDT), pg.875
Chapter 19: Fastening Devices and Methods, pg.908
Chapter 20: Working Drawings, pg.949
Chapter 21: Technical Data Presentation, pg.1064
Chapter 22: Mechanisms: Gears, Cams, Bearings, and Linkages, pg.1105
Chapter 23: Electronic Drawings, pg.1146
Chapter 24: Piping Drawings, pg.1163
Chapter 25: Welding Drawings, pg.1187
2. Technical Drawing with Engineering Graphics, 15th Edition, by Frederick E. Giesecke, Shawna Lockhart, Marla Goodman, Cindy M. Johnson (1077 pages), 2016
Chapter 1: The World-wide Language for Graphic Design, pg.2
Chapter 2: Layouts and Lettering, pg.30
Chapter 3: Visualization and Sketching, pg.62
Chapter 4: Geometry for Modeling and Design, pg.124
Chapter 5: Modeling and Design, pg.170
Chapter 6: Orthographic Projection, pg.234
Chapter 7: 2D Drawing Representation, pg.284
Chapter 8: Section Views, pg.326
Chapter 9: Auxiliary Views, pg.362
Chapter 10: Modeling for Manufacture, pg.414
Chapter 11: Dimensioning, pg.502
Chapter 12: Tolerancing, pg.546
Chapter 13: Threads, Fasteners, and Springs, pg.592
Chapter 14: Working Drawings, pg.636
Chapter 15: Drawing Control and Data Management, pg.710
Chapter 16: Gears and Cams, pg.730
Chapter 17: Electronic Diagrams, pg.756
Chapter 18: Structural Drawing, pg.780
Chapter 19: Landform Drawings, pg.808
Chapter 20: Piping Drawings, pg.828
Chapter 21: Welding Representation, pg.846
Chapter 22: Axonometric Projection, pg.W870
Chapter 23: Perspective Drawings, pg.W900
3. Engineering Drawing & Design, 6th Edition, by David A. Madsen and David P. Madsen (1104 pages), 2017
Chapter 1: Introduction to Engineering Drawing and Design, pg.2
Chapter 2: Drafting Equipment, Media, and Reproduction Methods, pg.39
Chapter 3: Computer-Aided Design and Drafting (CADD), pg.61
Chapter 4: Manufacturing Materials and Processes, pg.109
Chapter 5: Sketching Applications, pg.162
Chapter 6: Lines and Lettering, pg.181
Chapter 7: Drafting Geometry, pg.205
Chapter 8: Multiviews, pg.228
Chapter 9: Auxiliary Views, pg.259
Chapter 10: Dimensioning and Tolerancing, pg.277
Chapter 11: Fasteners and Springs, pg. 347
Chapter 12: Sections, Revolutions, and Conventional Breaks, pg.387
Chapter 13: Geometric Dimensioning and Tolerancing, pg.409
Chapter 14: Pictorial Drawings and Technical Illustrations, pg.495
Chapter 15: Working Drawings, pg.526
Chapter 16: Mechanisms: Linkages, Cams, Gears, and Bearings, pg.561
Chapter 17: Belt and Chain Drives, pg.601
Chapter 18: Welding Processes and Representations, pg.617
Chapter 19: Precision Sheet Metal Drafting, pg.644
Chapter 20: Electrical and Electronic Drafting, pg.669
Chapter 21: Industrial Process Piping, pg.717
Chapter 22: Structural Drafting, pg.773
Chapter 23: Heating, Ventilating, and Air-conditioning (HVAC) and Pattern Development, pg.847
Chapter 24: Civil Drafting, pg.899
Chapter 25: The Engineering Design Process, pg.950
Engineering Drawing and Design Student Companion Website, pg.973
4. Engineering Design and Graphics with SolidWorks by James D. Bethune (829 pages), 2017
Chapter 1: Getting Started, pg.1
Chapter 2: Sketch Entities and Tools, pg.41
Chapter 3: Features, pg.123
Chapter 4: Orthographic Views, pg.225
Chapter 5: Assemblies, pg.299
Chapter 6: Threads and Fasteners, pg.375
Chapter 7: Dimensioning, pg.439
Chapter 8: Tolerancing, pg.509
Chapter 9: Bearings and Fit Tolerances, pg.605
Chapter 10: Gears, pg.639
Chapter 11: Belts and Pulleys, pg.699
Chapter 12: Cams, pg.725
Chapter 13: Projects, after pg.774
5. Interpreting Engineering Drawings, 8th Edition, by Theodore J. Branoff (530 pages), 2016
Unit 1: Introduction: Line Types and Sketching, pg.1
Unit 2: Lettering and Title Blocks, pg.11
Unit 3: Basic Geometry: Circles and Arcs, pg.15
Unit 4: Working Drawings and Projection Theory, pg.22
Unit 5: Introduction to Dimensioning, pg.39
Unit 6: Normal, Inclined, and Oblique Surfaces, pg.52
Unit 7: Pictorial Sketching, pg.67
Unit 8: Machining Symbols and Revision Blocks, pg.78
Unit 9: Chamfers, Undercuts, Tapers, and Knurls, pg.86
Unit 10: Sectional Views, pg.91
Unit 11: One- and Two-View Drawings, pg.110
Unit 12: Surface Texture, pg.117
Unit 13: Introduction to Conventional Tolerancing, pg.130
Unit 14: Inch Fits, pg.142
Unit 15: Metric Fits, pg.150
Unit 16: Threads and Fasteners, pg.161
Unit 17: Auxiliary Views, pg.181
Unit 18: Development Drawings, pg.190
Unit 19: Selection and Arrangement of Views, pg.196
Unit 20: Piping Drawings, pg.202
Unit 21: Bearings, pg.214
Unit 22: Manufacturing Materials, pg.220
Unit 23: Casting Processes, pg.232
Unit 24: Violating True Projection: Conventional Practices, pg.249
Unit 25: Pin Fasteners, pg.264
Unit 26: Drawings for Numerical Control, pg. 274
Unit 27: Assembly Drawings, pg.280
Unit 28: Structural Steel, pg.289
Unit 29: Welding Drawings, pg.294
Unit 30: Groove Welds, pg.305
Unit 31: Other Basic Welds, pg.315
Unit 32: Spur Gears, pg.328
Unit 33: Bevel Gears and Gear Trains, pg.337
Unit 34: Cams, pg.347
Unit 35: Bearings and Clutches, pg.353
Unit 36: Ratchet Wheels, pg.362
Unit 37: Introduction to Geometric Dimensioning and Tolerancing, pg.368
Unit 38: Features and Material Condition Modifiers, pg.380
Unit 39: Form Tolerances, pg.394
Unit 40: The Datum Reference Frame, pg.402
Unit 41: Orientation Tolerances, pg.415
Unit 42: Datum Targets, pg.432
Unit 43: Position Tolerances, pg.440
Unit 44: Profile Tolerances, pg.461
Unit 45: Runout Tolerances, pg.469
6. Architectural Graphic Standards Student Edition, 12th Edition, by The American Institute of Architects (689 pages), 2017
Chapter 1: Functional Planning, pg.3
Chapter 2: Environment, pg.31
Chapter 3: Resilience in Buildings. Pg.53
Chapter 4: Architectural Construction Documentation, pg.77
Chapter 5: Concrete, pg.93
Chapter 6: Masonry, pg.107
Chapter 7: Metals, pg.125
Chapter 8: Wood, pg.141
Chapter 9: Glass, pg.165
Chapter 10: Element A: Substructure, pg.176
Chapter 11: Element B: Shell, pg.203
Chapter 12: Element C: Interiors, pg.363
Chapter 13: Element D: Services, pg.427
Chapter 14: Element E: Equipment and Furnishings, pg.517
Chapter 15: Element F: Special Construction, pg.565
Technical and engineering drawings express precise requirements or specifications that should be easy to interpret. There are certain types of lines used for graphical communication in technical and engineering drawing in order to convey clear messages, and abide by good professional standards. Generally, most of the lines used in practice are of uniform thickness and density.
It is vital for drafters, designers, engineers, and people to understand how and when to apply the variety of line styles which serve as a reliable means of passing on valuable information when drawn and positioned properly on drawing paper or computer.
Most objects drawn in technical and engineering drawing practice are somewhat complicated and contain a lot of planes, surfaces, and edges. In order to clearly distinguish all of them, it is important to use technical and engineering drawing lines effectively.
Lines make the difference; they are fundamental and perhaps the most important thing in technical and engineering drawings because they express or illustrate how shapes and sizes of objects would in real life after they are constructed.
In many cases, if every line has the same thickness, technical and engineering drawings would be confusing and difficult to interpret because some very important planes and parts of objects won’t stand out from dimension lines that describe only the outlook of objects.
By employing different types of lines on the basis of various thicknesses and designations, many features can be expressed in precise ways which would otherwise be difficult to express. To make sure everybody can interpret drawings the same way, the use of different types of lines was established decades ago by various committees that recognize the importance of standardization in technical & engineering drawing.
The most popular types of lines form the core of technical and engineering drawings. Some lines are dark, while others are light; some are thick, while others are thin; some are solid all through, while others are dashed in various ways.
The figures below illustrate the types of lines popularly used in technical and engineering drawings.
Figure 1: 8 types of lines used in technical & engineering drawing
Figure 2: 4 extra types of lines used in technical & engineering drawing
Figure 3: Other types of thin lines used in technical & engineering drawing
Figure 4: Hatching & cutting plane lines used in technical & engineering drawing
Figure 5: Example of a drawing that uses 6 different types of lines
Technical and engineering drawings/graphics are a bit more cumbersome or involving than artistic drawings because they require the use of terms, symbols, and rules that are somewhat universal, and which knowledgeable people can understand and use in communicating.
Practitioners of both technical and engineering drawing have done a lot of work over decades to harmonize terms, symbols, and rules universally, and in such a way that drawings made or produced in one city can be sent to another city, and understood by other people who can assembly the drawings and manufacture objects that were made or drawn somewhere else.
Standardization has made it possible to interpret one drawing in different parts of the world, no matter the language used; basically, drawings have only one interpretation. For well over 100+ years, a lot of countries set up committees on standardization in order to accomplish this goal.
Usually, committees decide on very important factors such as the best methods that could give the clearest presentation of drawings, dimensioning, symbols, and allowances (tolerances)—amongst many others.
In addition, different line styles are considered, adopted, and used to represent visible or hidden lines, and also indicate the centers of different objects, shapes, and features. If a single interpretation is desired globally, then the rules of standardization must be strictly adhered to and correctly interpreted.
Committees from countries that are part of the International Organization for Standardization (ISO)—the universal committee on standardization
Various countries have organizations, bodies, or committees that have shaped how technical and engineering drawing is practiced. Just to name a few—the British Standards Institution (BSI), established in 1901, was the world’s first national standards body; in the United States, technical and engineering drawing standards are established by the American Society of Mechanical Engineers (ASME); while Canada has the Canadian Standards Association (CSA). Generally, across the globe there exist several other organizations or bodies; all of which we won’t be able to list in this article.
The British Standards Institution (BSI) has done a lot of work and published approximately 20,000 standards. Every year it issues around 2000 new and revised standards that cover new materials, emerging processes, and technologies. In addition, it keeps the technical content of existing standards up-to-date.
Generally, members of organizations, bodies, and committees from many countries are part of the worldwide committee on standardization, which is popularly known as the International Organization for Standardization (ISO), and made up of national standards institutes from large and small countries which have different standards of living: basically, industrialized, or developed.
ISO develops technical standards that add immeasurable value to all types of businesses that use technical and engineering drawing; furthermore, it makes development, manufacturing, and supply of services and products much more efficient and safe and also makes trading easier and fairer between countries that don’t use a common language.
Although a lot of work has been done in the area of standardization, there are still certain areas of drawing practice that national standards have not yet been established for; for example, simplified drafting. In such a case, practitioners and authors have adopted certain practices used by leading industries, especially in the United States.
After the shape and size of any technical or engineering drawings are constructed, other important information for constructing the object is provided in such a way that it can be easily recognized by anyone who is knowledgeable or familiar with technical or engineering drawing.
A complete and comprehensive understanding of an object cannot be acquired by using only one pictorial view because many details of the object won’t be expressed, and may be hidden or not clearly shown if the object is viewed from only one side or direction. Because of this, any practitioner or drafter must express an object through a number of views of an object from different directions or axes. Views, such as top view, front view, and side view—either right or left—and so on, are employed in drawings in order to project one view from another, as shown in the figure below.
Orthographic views of an airplane
Application of standardization
Standardization has given a lot of uniformity to drawings and has made it easier for people from different cultural backgrounds to make use of universally accepted and adopted ideas. That’s why designers have been urged to use stock standard lengths of screws wherever possible. Lengths of screws include: 3, 4, 5, 6, 8, 10, 12, 16, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, and 200 mm.
If the length of a screw required is over 200 mm, then increments of 20 mm become the preferred ISO lengths. Sometimes this is necessary because not all diameters of screws are available for the lengths listed in the previous paragraph; for example, the lengths available for an M3 screw range between 5 and 35 mm; while the lengths available for an M10 screw range between 12 and 100 mm for a particular type of screw head. Different ranges do not always cover different types of screw heads—hence the recommendation to always check any stock lists used in technical and engineering drawing practice.
The word “dimension” can be defined as the magnitude of a shape or object in a particular direction; it can also be defined as the linear measurement of a line used to describe the value of the length, breadth, height, thickness, or circumference of an object or structure. A dimension is one of the three coordinates of the position of a point, line, area, or volume relative to three imaginary but real axes: x, y, and z.
The most common terms used to describe or express dimensions are height (or depth), length, breadth (or width); all three are often interchanged, with one dimension often being referred to by another name. The most important thing to take note of is the obvious fact each dimension or description refers to the orientation of an object along a particular axis; especially the x, y, and z axes, respectively.
Many geometric shapes have two dimensions, while other types have three dimensions: width, depth, and height; or length, width, and height—whichever combination. The choice of terms used to describe the dimensions of an object depends on the orientation of the shape and size of the object.
Figure 1: A 3D object (cube) expressed in terms of height, length and depth. (Image credit: Curiositi.)
Figure 2: 2D and 3D rectangular objects expressed in terms of a combination of any 2 and 3 terms: length, breadth, and height. (Image credit: Siyavula.)
There are quite a number of geometrical shapes used in technical and engineering drawing; they include cones, cubes, cylinders, prisms, pyramids, spheres, toroids (doughnut-shaped objects), trapeziums, etc.
Whenever any two different shapes intersect/are used together, a kind of curve, interpenetration or intersection is employed to make sure they fit together. It is very important that students or practitioners be able to draw curves and intersections in order to make good drawings and communicate clearly using the different types of technical drawing.
Figure 3: Types or shapes of objects in 2D. (Image credit: Toppr.)
Figure 4: Types or shapes of objects in 3D. (Image credit: Toppr.)
Usually, a spherical-shaped object like a basketball is usually described as having a radius or diameter, which generally, is just one descriptive term—with the height of a basketball having the same dimension as the diameter.
Usually, a cylindrical shape such as a baseball bat can be described by using terms such as “diameter”, and “length” or “height”—depending on whether it is standing up erect, or lying down flat. A hockey puck would be described using diameter, and width or thickness—i.e., two terms. On the other hand, objects that are not spherical or cylindrical could require three terms to appropriately describe their overall shape—as you might have noticed in Figure 1 (the first figure in this article).
The terms that would be used to describe a car, for instance, would include length, width, and height. Typically, width, height, and breadth would be used to describe a cupboard; while length, width, and thickness could be used to describe a sheet of drawing paper.
Generally, the terms used to describe the dimensions, sizes, and shapes of objects are interchangeable, and usually done with respect to the position or orientation of objects when they are being viewed from a particular axis. For example, if a rectangular block is being viewed while it is lying flat on the ground (say, in 2D), it could be described as having a width and height; but if it is placed in a vertical standing position (say, in 3D), and viewed from the side, it could be described as having a height, width, and breadth.
In order to avoid confusion, it is advisable that distances observed or taken from left to right be referred to as “width”, distances taken from front to back be referred to as “breadth”, and vertical distances taken from bottom to top (or vice versa) be referred to as “height”. Sometimes, the longest dimension of an object is referred to as the “length”.
In some other instances, there are certain unpopular shapes that are defined by applying mathematical methods; they include the type of complex shapes used in the design of structures such as automobiles, aircraft, and the hulls of ships—amongst many others.
This article defines orthographic drawing (drafting or projection) and uses 21 images to illustrate the meaning and types of orthographic drawing. The eBook/technical drawing PDF document for this article is available for free download at the end of the article (along with a list of world-class technical & engineering drawing/graphics books in electronic form/PDF, available for sale at cheap prices). Generally, both the article and eBook elaborate on the following:
Definition of orthographic drawing
Types of orthographic drawing
First angle projection
Third angle projection
Orthographic drawing views
Orthographic drawing tutorial & practice
Tools required for orthographic drawing practice
General procedure
Applications of orthographic drawing practice
Orthographic drawing shapes/objects for practice
Conclusion
You can click a link at the end of this article, and download a free eBook which contains all the content in this article.
1. Definition of orthographic drawing
Orthographic drawing, which is one of the three types of parallel projections (orthographic, oblique, and axonometric), can be defined as a type of technical drawing in which 3-dimensional (3D) objects are represented in 2 dimensions (2D) by projecting planes (consisting of 2 major axes) of objects so that they are parallel with the plane of the media (paper, or computer) they are projected upon.
The two major types of orthographic drawing use two-dimensional views (obtained from different directions or lines of sight) to represent different parts of three-dimensional objects, or planes of objects viewed from/along different axes—typically, the x, y, and z axes.
Generally, the best way to fully express all of the most important visible parts of any 3D object in 2D views—in either first angle orthographic projection or third angle orthographic projection—is by using a maximum number of views, which in most cases is six.
However, in practice most people or organizations use three or four views to illustrate how shapes and sizes of various parts of an object look. Generally speaking, the number of views used in an orthographic drawing or projection depends on the purpose and objective of a drawing.
2. Types of orthographic drawing
Orthographic drawing (also known as orthographic projection) consists of two types: first angle projection, and third angle projection.
First angle projection
In first angle projection, which is popularly practiced in Europe, whenever six views are used to illustrate how the sides of a 3D object look from six directions (as shown in Figure 1 below), they are usually arranged in the following manner (as shown in Figure 2 below):
The bottom view E is placed at the top of the paper or computer screen.
The front view A is placed beneath the bottom view E.
The top view D is placed beneath front view A (i.e., at the bottom of the paper or computer screen.
The right view C is placed on the left side of front view A.
The left view B is placed on the right side of front view A.
The back/rear view F (which is not shown in Figure 2) is usually placed at the extreme left or right—whichever position is convenient.
Figure 1: Six directions for six views. (Image Credit: Simmons, C. H. and Maguire, D. E. (2004). Manual of Engineering Drawing: p. 33.)
Figure 2: Five views of first angle projection; the sixth view F would depend on the shape of the back/rear view of the object. (Image Credit: Simmons, C. H. and Maguire, D. E. (2004). Manual of Engineering Drawing: p. 34.)
Whenever four views are used, the front view is usually placed at the top of a medium (paper, computer screen, etc.) along with the right side view which is placed at the left side of the front view, while the left side view is placed at the right side of the front view, and the top view (T) is placed alone beneath the front view.
It has to be noted that in many first angle orthographic drawing practices, three views could be sufficient enough to describe the shapes and dimensions of the most important sides of an object which actually exist in 3D as shown in Figure 3 below:
Figure 3: A three dimensional object with 7 visible edges (A, B, C, D, E, F, and G)
Third Angle Projection
In third angle projection, which is mostly practiced in North America, whenever six views are used to describe the sides of a 3D object from six different directions (as shown in Figure 1 above), they are usually arranged in the following manner (as shown in Figure 4 below):
The top view D is placed at the top of the paper or computer screen.
The front view A is placed beneath the top view D.
The bottom view E is placed beneath front view A (i.e., at the bottom of the paper or computer screen).
The right view C is placed on the right side of front view A.
The left view B is placed on the left side of front view A.
The back/rear view F (which is not shown in Figure 2) is usually placed at the extreme left or right—whichever position is convenient.
Figure 4: Five views of third angle projection; the sixth view F would depend on the shape of the back/rear view of the object. (Image Credit: Simmons, C. H. and Maguire, D. E. (2004). Manual of Engineering Drawing: p. 34.)
Whenever four views are used, the top view is usually placed alone at the top of a medium (paper, computer screen, etc.), while the front view is placed beneath the top view, and the right side view is placed at the right side of the front view, while the left side view is placed at the left side of the front view. (Note that third angle projection is the most popular type of orthographic drawing or projection.)
Generally speaking, the difference between first angle projection and third angle projection depends on where each view is placed on paper or computer screen according to the universally accepted requirements of the two main types of orthographic drawing/projection.
3. Orthographic drawing views
There is no general rule per se, but the best or most recommendable way to fully express the most important visible planes/parts of any 3D object in 2D views, is by using as many views as possible: probably between three and six views.
Unlike in Figure 1 above, whenever six views are used, different directions (lines of sight projected on the sides of an object) can be chosen to illustrate the top, bottom, front, rear/back, left and right views, respectively, as can be seen in Figure 5 below:
Figure 5: Six different directions (lines of sight) for six views. (Image credit: Google.)
The third angle projection of Figure 5 is shown in Figure 6 below:
Figure 6: Third angle projection of object in Figure 5. (Image credit: Google.)
The orthographic drawings or projections of other objects/shapes can be viewed in Figures 7, 8, and 9 below:
Figure 7: First angle projection of an object: (Image credit: Google.)
Figure 8: Projection of an object. (Image credit: Google.)
Figure 9: Third angle projection of an object that has dimensions in millimeters. (Image credit: Google.)
Always remember that in many orthographic drawing practices across the world, the number of views chosen or used, usually depends on the number of views required or needed.
4. Orthographic Drawing Tutorial & Practice
Tools required for orthographic drawing practice
With regular drawing practice, it is very easy to learn and perfect orthographic drawing skills. The tools usually required for practicing orthographic drawing are quite the same as the ones specified in technical and engineering drawing, respectively. Generally, the tools include:
Drawing board.
Drawing paper: either Ao, A1, A2, A3, and A4.
Drawing pencil.
Eraser.
30°×60° and 45°×45° set squares.
300 mm (30 cm) ruler.
T-square.
Drawing compasses
Figure 10: Drawing board and drawing paper
Figure 11: A set consisting of a drawing board, drawing paper, tape/clips, set square for drawing vertical lines, and T-square for drawing horizontal lines. (Image Credit: The Hong Kong Polytechnic. (N.D). Fundamentals of Engineering Drawing & CAD: Engineering Drawing Lesson 1: p. 10.)
Figure 12: 45°×45° (bigger: on the left), and 30°×60° (smaller: on the right) set-squares
Figure 13: T-square
Figure 14: Drawing compasses (for drawing circular and elliptical shapes)
T-squares and set squares must be aligned perfectly on the pure/true x and y axes, respectively, before perfect vertical or horizontal lines can be produced. It will be difficult to produce good orthographic drawings without drawing or projecting perfect vertical and horizontal lines.
General Procedure
Generally, when projecting sides or different views of 3D objects in 2D, a certain degree of concentration will be needed to ensure that shapes, sizes or dimensions are consistent and accurate. The following are recommended when making orthographic projections:
Estimate the area of paper that would be enough to draw all necessary and important views. In addition, determine an appropriate scale for your drawings. A scale is any ratio (examples: 1:10, 1:100, 1:1000, etc.) of the size of an object on paper, to the actual size of the same object in real life. Common scales for “enlargement of objects” include: 3:1, 6:1, 10:1, etc. On the other hand, common scales for “reduction of objects” include: 1:3, 1:6, 1:10, etc.
Put equal distances (which should also be considered in the total area that would be enough to accommodate all views) between views; vertically (for the top, front, and bottom views), and horizontally (for the left, right, and back/rear views).
When drawing any view—whether square-, rectangular-, or circular-shaped—mark the center lines of each shape and the center/centroid of each shape. Center lines are very important, not just because they are center lines, but because they serve many other purposes, one of them being that they help in establishing other points and lines in drawings.
Draw the top view, and project the most visible and important lines into the front view, or vice versa.
After drawing the front view, the right and left side views can be projected and drawn. In addition, the bottom and back/rear view can be also be constructed if required.
Figure 15: Top view of an object drawn on drawing paper
As an example, in order to draw perfectly straight vertical and horizontal lines for the two dimensional (2D) top view ABCD of a 3D object on paper (as shown in Figure 15 above), the following steps should be taken:
Points and A and B should be the same distance away from the top border line on the drawing paper.
Points and C and D should be the same distance away from the bottom border line on the paper.
Points and A and C should be the same distance away from the left border line on the paper.
Points and B and D should be the same distance away from the right border line on the paper.
Applications of orthographic drawing practice
Orthographic drawings have many applications scattered across various fields that require planning and designing such as architecture, construction, design, engineering, environment, estate management, manufacturing, surveying, etc.
Orthographic drawings are usually produced according to precision and requirements. It is possible for an orthographic drawing that has been produced in one country, to be used to manufacture an object in another country.
Orthographic drawing shapes/objects for practice
Like we said earlier: “practice makes perfect”. In order to strengthen your orthographic drawing skills, you may practice how to draw the views of the following objects:
Figure 16: Third angle projection of object with six views. (Image credit: The Hong Kong Polytechnic. (N.D). Fundamentals of Engineering Drawing & CAD: Engineering Drawing Lesson 1: p. 32.)
Figure 17: Three commonly practiced orthographic views. (Image credit: The Hong Kong Polytechnic. (N.D). Fundamentals of Engineering Drawing & CAD: Engineering Drawing Lesson 1: p. 33.)
The three main 2D views, and six general 2D views of an L-shaped object can be seen in Figures 18 and 19, respectively.
Figure 18: Three popular 2D views. (Image credit: Dr. Akhilesh Kumar Maurya. (N.D.). Orthographic Projections (ME 111): p. 13.)
Figure 19: Six views of the object shown in Figure 18 above. (Image credit: Dr. Akhilesh Kumar Maurya. (N.D.). Orthographic Projections (ME 111): p. 15.)
The use of colors makes it easier to understand, locate, and draw 2D views of 3D objects. With the aid of colors on objects, you can study and practice how to draw Figures 20 and 21, respectively:
Figure 20: The use of colors in orthographic projection. (Image credit: Dr. Akhilesh Kumar Maurya. (N.D.). Orthographic Projections (ME 111):p. 36.)
Figure 21: Three orthographic third angle projection views with colors. (Image credit: Dr. Akhilesh Kumar Maurya. (N.D.). Orthographic Projections (ME 111):p. 36.)
Concluding remarks
Anyone who is interested in succeeding with orthographic drawing or projection must practice consistently; there is no other easy or painless way out. The more one practices, the more proficient they will become in drawing and developing newer, sharper and more efficient ways to draw. Always remember that practice makes perfect; therefore, always practice.
If you’re interested in viewing, studying and drawing various, click here; also, if you’re interested in downloading the eBook for this article, click here and download it for free.
Thank you for reading.
Interested in buying world-class technical and engineering drawing eBooks? Please, read on.
Knowledge is power. The more you read, study, and absorb, the more you can greatly magnify your visualization process and become better. There is no limit.
For further reading and study of topics on technical and engineering drawings/graphics—which is essential for your education/future as an engineer/technologist and—we advise that you make a habit of reading good books.
It’s possible to get a good book from a friend or purchase it either from a local bookstore (offline) or online. In case you’d be interested in purchasing, we have six high-quality technical & engineering drawings/graphics books (eBooks/PDF books) for sale at cheap prices.
Continue scrolling down and you’ll come across their respective titles, number of pages, and lists of chapters. Each book is available for purchase at a cost of $5 (or 2,500 Naira) per book; if you wish to purchase all books, you’ll get a discount of $5 (2,500 Naira) and purchase 6 books for $25 (12,000 Naira) instead of $30 (15,000 Naira).
Note
For the past 3 years, until January 19, 2022, all the eBooks on this site were always available for free download (no payment). However, as from January 20, 2022, we introduced payments to be able to acquire, at least, little funds for the upkeep of our domain name and site maintenance for the benefit of present and future visitors who will read our articles on topics of their interest.
Instructions for payment
To purchase a copy or copies:
(1) Pay through any of the following 3 payment methods:
Send Bitcoin equivalent of USD to: 13jRM5DYmYSHvMraPB7c6JGhNk8dKzCVPg
Send Ethereum equivalent of USD to: 0xa571807E344D83797ebdFb01e3aFB3F7F43Da29B
Send USD ($) through WorldRemit, Remitly, or any other trustworthy platform/site to the following bank account:
Bank name: Guaranty Trust Bank (GTBank), Nigeria
Account name: Godwin Terhemba Ihagh
Account number: (Send Dollars to 0620810523; Naira to 0210490937)
Note: If you’d like to pay using a different payment option or another cryptocurrency that isn’t listed above, contact us through our email: godwinihagh@gmail.com or Whatsapp number: +2348033219907.
(2) After payment, take and send a screenshot(s) of the transaction(s) as evidence of payment to either our email: godwinihagh@gmail.com or Whatsapp number: +2348033219907.
(3) After confirming payment, we’ll provide you with access to the book(s) which is/are easy-to-read and contain(s) comprehensive coverage of technical and engineering drawing/drafting and design instructions that comply with present-day industry standards.
The titles of the books (arranged in decreasing order of priority [from 1 to 6]—based on our assessment) and their respective number of pages and titles of chapters are as follows:
1. Technical Graphics Communication, 4th Edition, by Gary R. Bertoline, Eric N. Wiebe, Nathan W. Hartman, William A. Ross (1335 pages), 2009
Chapter 1: Introduction to Graphics Communication, pg.5
Chapter 2: The Engineering Design Process, pg.27
Chapter 3: Design in Industry, pg.46
Chapter 4: The Role of Technical Graphics in Production, Automation, and Manufacturing Processes, pg.109
Chapter 5: Design & Visualization, pg.135
Chapter 6: Technical Drawing Tools, pg.187
Chapter 7: Sketching and Text, pg.237
Chapter 8: Engineering Geometry and Construction, pg.305
Chapter 9: Three-dimensional Modeling, pg.399
Chapter 10: Multiview Drawings, pg.488
Chapter 11: Axonometric and Oblique Drawings, pg.577
Chapter 12: Perspective Drawings, pg.631
Chapter 13: Auxiliary Views, pg.652
Chapter 14: Fundamentals of Descriptive Geometry, pg.691
Chapter 15: Intersections and Developments, pg.716
Chapter 16: Section Views, pg.759
Chapter 17: Dimensioning and Tolerancing Practices, pg.818
Chapter 18: Geometric Dimensioning and Tolerancing (GDT), pg.875
Chapter 19: Fastening Devices and Methods, pg.908
Chapter 20: Working Drawings, pg.949
Chapter 21: Technical Data Presentation, pg.1064
Chapter 22: Mechanisms: Gears, Cams, Bearings, and Linkages, pg.1105
Chapter 23: Electronic Drawings, pg.1146
Chapter 24: Piping Drawings, pg.1163
Chapter 25: Welding Drawings, pg.1187
2. Technical Drawing with Engineering Graphics, 15th Edition, by Frederick E. Giesecke, Shawna Lockhart, Marla Goodman, Cindy M. Johnson (1077 pages), 2016
Chapter 1: The World-wide Language for Graphic Design, pg.2
Chapter 2: Layouts and Lettering, pg.30
Chapter 3: Visualization and Sketching, pg.62
Chapter 4: Geometry for Modeling and Design, pg.124
Chapter 5: Modeling and Design, pg.170
Chapter 6: Orthographic Projection, pg.234
Chapter 7: 2D Drawing Representation, pg.284
Chapter 8: Section Views, pg.326
Chapter 9: Auxiliary Views, pg.362
Chapter 10: Modeling for Manufacture, pg.414
Chapter 11: Dimensioning, pg.502
Chapter 12: Tolerancing, pg.546
Chapter 13: Threads, Fasteners, and Springs, pg.592
Chapter 14: Working Drawings, pg.636
Chapter 15: Drawing Control and Data Management, pg.710
Chapter 16: Gears and Cams, pg.730
Chapter 17: Electronic Diagrams, pg.756
Chapter 18: Structural Drawing, pg.780
Chapter 19: Landform Drawings, pg.808
Chapter 20: Piping Drawings, pg.828
Chapter 21: Welding Representation, pg.846
Chapter 22: Axonometric Projection, pg.W870
Chapter 23: Perspective Drawings, pg.W900
3. Engineering Drawing & Design, 6th Edition, by David A. Madsen and David P. Madsen (1104 pages), 2017
Chapter 1: Introduction to Engineering Drawing and Design, pg.2
Chapter 2: Drafting Equipment, Media, and Reproduction Methods, pg.39
Chapter 3: Computer-Aided Design and Drafting (CADD), pg.61
Chapter 4: Manufacturing Materials and Processes, pg.109
Chapter 5: Sketching Applications, pg.162
Chapter 6: Lines and Lettering, pg.181
Chapter 7: Drafting Geometry, pg.205
Chapter 8: Multiviews, pg.228
Chapter 9: Auxiliary Views, pg.259
Chapter 10: Dimensioning and Tolerancing, pg.277
Chapter 11: Fasteners and Springs, pg. 347
Chapter 12: Sections, Revolutions, and Conventional Breaks, pg.387
Chapter 13: Geometric Dimensioning and Tolerancing, pg.409
Chapter 14: Pictorial Drawings and Technical Illustrations, pg.495
Chapter 15: Working Drawings, pg.526
Chapter 16: Mechanisms: Linkages, Cams, Gears, and Bearings, pg.561
Chapter 17: Belt and Chain Drives, pg.601
Chapter 18: Welding Processes and Representations, pg.617
Chapter 19: Precision Sheet Metal Drafting, pg.644
Chapter 20: Electrical and Electronic Drafting, pg.669
Chapter 21: Industrial Process Piping, pg.717
Chapter 22: Structural Drafting, pg.773
Chapter 23: Heating, Ventilating, and Air-conditioning (HVAC) and Pattern Development, pg.847
Chapter 24: Civil Drafting, pg.899
Chapter 25: The Engineering Design Process, pg.950
Engineering Drawing and Design Student Companion Website, pg.973
4. Engineering Design and Graphics with SolidWorks by James D. Bethune (829 pages), 2017
Chapter 1: Getting Started, pg.1
Chapter 2: Sketch Entities and Tools, pg.41
Chapter 3: Features, pg.123
Chapter 4: Orthographic Views, pg.225
Chapter 5: Assemblies, pg.299
Chapter 6: Threads and Fasteners, pg.375
Chapter 7: Dimensioning, pg.439
Chapter 8: Tolerancing, pg.509
Chapter 9: Bearings and Fit Tolerances, pg.605
Chapter 10: Gears, pg.639
Chapter 11: Belts and Pulleys, pg.699
Chapter 12: Cams, pg.725
Chapter 13: Projects, after pg.774
5. Interpreting Engineering Drawings, 8th Edition, by Theodore J. Branoff (530 pages), 2016
Unit 1: Introduction: Line Types and Sketching, pg.1
Unit 2: Lettering and Title Blocks, pg.11
Unit 3: Basic Geometry: Circles and Arcs, pg.15
Unit 4: Working Drawings and Projection Theory, pg.22
Unit 5: Introduction to Dimensioning, pg.39
Unit 6: Normal, Inclined, and Oblique Surfaces, pg.52
Unit 7: Pictorial Sketching, pg.67
Unit 8: Machining Symbols and Revision Blocks, pg.78
Unit 9: Chamfers, Undercuts, Tapers, and Knurls, pg.86
Unit 10: Sectional Views, pg.91
Unit 11: One- and Two-View Drawings, pg.110
Unit 12: Surface Texture, pg.117
Unit 13: Introduction to Conventional Tolerancing, pg.130
Unit 14: Inch Fits, pg.142
Unit 15: Metric Fits, pg.150
Unit 16: Threads and Fasteners, pg.161
Unit 17: Auxiliary Views, pg.181
Unit 18: Development Drawings, pg.190
Unit 19: Selection and Arrangement of Views, pg.196
Unit 20: Piping Drawings, pg.202
Unit 21: Bearings, pg.214
Unit 22: Manufacturing Materials, pg.220
Unit 23: Casting Processes, pg.232
Unit 24: Violating True Projection: Conventional Practices, pg.249
Unit 25: Pin Fasteners, pg.264
Unit 26: Drawings for Numerical Control, pg. 274
Unit 27: Assembly Drawings, pg.280
Unit 28: Structural Steel, pg.289
Unit 29: Welding Drawings, pg.294
Unit 30: Groove Welds, pg.305
Unit 31: Other Basic Welds, pg.315
Unit 32: Spur Gears, pg.328
Unit 33: Bevel Gears and Gear Trains, pg.337
Unit 34: Cams, pg.347
Unit 35: Bearings and Clutches, pg.353
Unit 36: Ratchet Wheels, pg.362
Unit 37: Introduction to Geometric Dimensioning and Tolerancing, pg.368
Unit 38: Features and Material Condition Modifiers, pg.380
Unit 39: Form Tolerances, pg.394
Unit 40: The Datum Reference Frame, pg.402
Unit 41: Orientation Tolerances, pg.415
Unit 42: Datum Targets, pg.432
Unit 43: Position Tolerances, pg.440
Unit 44: Profile Tolerances, pg.461
Unit 45: Runout Tolerances, pg.469
6. Architectural Graphic Standards Student Edition, 12th Edition, by The American Institute of Architects (689 pages), 2017
Chapter 1: Functional Planning, pg.3
Chapter 2: Environment, pg.31
Chapter 3: Resilience in Buildings. Pg.53
Chapter 4: Architectural Construction Documentation, pg.77
Chapter 5: Concrete, pg.93
Chapter 6: Masonry, pg.107
Chapter 7: Metals, pg.125
Chapter 8: Wood, pg.141
Chapter 9: Glass, pg.165
Chapter 10: Element A: Substructure, pg.176
Chapter 11: Element B: Shell, pg.203
Chapter 12: Element C: Interiors, pg.363
Chapter 13: Element D: Services, pg.427
Chapter 14: Element E: Equipment and Furnishings, pg.517
Chapter 15: Element F: Special Construction, pg.565
Basic Components of Engineering Graphics—the Code of Practice
Basic technical drawing is an essential component of all types of engineering graphics, nationally, and internationally. Within national and international trade, goods that are technical in nature almost always need to be accompanied by service diagrams or technical illustrations that express shapes, dimensions, and how components work whenever projections are assembled.
Examples of services could include consultancy work, design of communication towers, installation procedures for technological inventions, or even instructions on how to assemble simple devices.
Whenever information is exchanged, especially between people who don’t understand/use a common verbal language, technical drawings can give clarity, even when language barriers exist.
Before a unified approach was ever agreed on, IS:696: “Code of practice for general engineering drawing” was originally issued in 1955, and revised twice in 1960 and 1972 respectively.
Growing international cooperation and exportation of technology has necessitated the development of an internationally unified format that consists of components, rules, codes, conventions, and symbols that illustrate the language of technical drawing with engineering graphics.
Since the publication of the code of practice, many countries have made a lot of progress in standardizing the components of technical drawing with engineering graphics because of their adherence to the mutual agreement on the use of codes in and between countries.
The basic components of the code of practice used in technical drawing with engineering graphics include:
List of drawing tools and items.
Sizes/layout of drawing sheets.
Folding of drawing sheets: how to fold drawing sheets.
Assembly drawings.
2-D and 3-D views.
Methods of dimensioning.
Methods of sectioning.
Cross-sectional views.
Half-sections.
Method for indicating surface texture.
General principles for dimensioning.
General principles of presentation: how to present drawings.
Linear and angular boundaries/tolerances for engineering and technical drawings.
Drawings for welding and metalwork.
General scales used in drawing.
Lines: thicknesses, spacing, and proportional dimensions.
In the technologically advanced world of today, technical drawing with engineering graphics and design employs every important cognitive and manipulative skill in order to aid engineering graphical communication which uses lines, dimensions, scales, symbols, and signs to illustrate how products, processes, services, and systems look and work.
Technical drawing is applied in many fields, one of which is engineering graphics and design. Many students usually study technical drawing before gaining admission to read engineering and study engineering graphics which is just one out of many engineering subjects. The transition from technical drawing to engineering graphics and further study is usually much easier for students who have had past experience in technical drawing.
Although many people assume that technical drawing is the same as engineering graphics, there is actually a difference between the two: technical drawing is generally employed in producing diagrams and representations of object and shapes on paper, while engineering graphics is a technique used by engineers to produce engineering design drawings, including pictorial representations of data in computer-aided design (CAD) and manufacture with the use of softwares.
Engineering graphics is somewhat an advanced type of technical drawing that clearly expresses the practical requirements for engineering forms or structures. Technical drawing goes hand in hand with engineering drafting graphics and design. Generally, whenever pencil and paper, or computer is used for drafting, it must be ensured that drafts are clear and visible enough to demonstrate how things work/would work.
The procedure, skill, or actions often used to produce engineering graphics can be regarded as technical drawing or drafting. Note that technical drawing is also be applied in disciplines that are not usually regarded as fields of engineering; examples include landscaping, architecture, environmental health science, cabinet making, garment-making, etc.
Engineering graphics often combines many colors, various texts, and illustrations in order to communicate clearly and effectively using drawings, especially with people who understand the language of technical, or engineering drawing.
The complete eBook of this article can be obtained by following the links below and reading the contents. Basically, both the article and eBook discuss the following topics which can be read by following the links below:
Interested in buying world-class technical and engineering drawing eBooks? Please, read on.
Knowledge is power. The more you read, study, and absorb, the more you can greatly magnify your visualization process and become better. There is no limit.
For further reading and study of topics on technical and engineering drawings/graphics—which is essential for your education/future as an engineer/technologist and—we advise that you make a habit of reading good books.
It’s possible to get a good book from a friend or purchase it either from a local bookstore (offline) or online. In case you’d be interested in purchasing, we have six high-quality technical & engineering drawings/graphics books (eBooks/PDF books) for sale at cheap prices.
Continue scrolling down and you’ll come across their respective titles, number of pages, and lists of chapters. Each book is available for purchase at a cost of $5 (or 2,500 Naira) per book; if you wish to purchase all books, you’ll get a discount of $5 (2,500 Naira) and purchase 6 books for $25 (12,000 Naira) instead of $30 (15,000 Naira).
Note
For the past 3 years, until January 19, 2022, all the eBooks on this site were always available for free download (no payment). However, as from January 20, 2022, we introduced payments to be able to acquire, at least, little funds for the upkeep of our domain name and site maintenance for the benefit of present and future visitors who will read our articles on topics of their interest.
Instructions for payment
To purchase a copy or copies:
(1) Pay through any of the following 3 payment methods:
Send Bitcoin equivalent of USD to: 13jRM5DYmYSHvMraPB7c6JGhNk8dKzCVPg
Send Ethereum equivalent of USD to: 0xa571807E344D83797ebdFb01e3aFB3F7F43Da29B
Send USD ($) through WorldRemit, Remitly, or any other trustworthy platform/site to the following bank account:
Bank name: Guaranty Trust Bank (GTBank), Nigeria
Account name: Godwin Terhemba Ihagh
Account number: (Send Dollars to 0620810523; Naira to 0210490937)
Note: If you’d like to pay using a different payment option or another cryptocurrency that isn’t listed above, contact us through our email: godwinihagh@gmail.com or Whatsapp number: +2348033219907.
(2) After payment, take and send a screenshot(s) of the transaction(s) as evidence of payment to either our email: godwinihagh@gmail.com or Whatsapp number: +2348033219907.
(3) After confirming payment, we’ll provide you with access to the book(s) which is/are easy-to-read and contain(s) comprehensive coverage of technical and engineering drawing/drafting and design instructions that comply with present-day industry standards.
The titles of the books (arranged in decreasing order of priority [from 1 to 6]—based on our assessment) and their respective number of pages and titles of chapters are as follows:
1. Technical Graphics Communication, 4th Edition, by Gary R. Bertoline, Eric N. Wiebe, Nathan W. Hartman, William A. Ross (1335 pages), 2009
Chapter 1: Introduction to Graphics Communication, pg.5
Chapter 2: The Engineering Design Process, pg.27
Chapter 3: Design in Industry, pg.46
Chapter 4: The Role of Technical Graphics in Production, Automation, and Manufacturing Processes, pg.109
Chapter 5: Design & Visualization, pg.135
Chapter 6: Technical Drawing Tools, pg.187
Chapter 7: Sketching and Text, pg.237
Chapter 8: Engineering Geometry and Construction, pg.305
Chapter 9: Three-dimensional Modeling, pg.399
Chapter 10: Multiview Drawings, pg.488
Chapter 11: Axonometric and Oblique Drawings, pg.577
Chapter 12: Perspective Drawings, pg.631
Chapter 13: Auxiliary Views, pg.652
Chapter 14: Fundamentals of Descriptive Geometry, pg.691
Chapter 15: Intersections and Developments, pg.716
Chapter 16: Section Views, pg.759
Chapter 17: Dimensioning and Tolerancing Practices, pg.818
Chapter 18: Geometric Dimensioning and Tolerancing (GDT), pg.875
Chapter 19: Fastening Devices and Methods, pg.908
Chapter 20: Working Drawings, pg.949
Chapter 21: Technical Data Presentation, pg.1064
Chapter 22: Mechanisms: Gears, Cams, Bearings, and Linkages, pg.1105
Chapter 23: Electronic Drawings, pg.1146
Chapter 24: Piping Drawings, pg.1163
Chapter 25: Welding Drawings, pg.1187
2. Technical Drawing with Engineering Graphics, 15th Edition, by Frederick E. Giesecke, Shawna Lockhart, Marla Goodman, Cindy M. Johnson (1077 pages), 2016
Chapter 1: The World-wide Language for Graphic Design, pg.2
Chapter 2: Layouts and Lettering, pg.30
Chapter 3: Visualization and Sketching, pg.62
Chapter 4: Geometry for Modeling and Design, pg.124
Chapter 5: Modeling and Design, pg.170
Chapter 6: Orthographic Projection, pg.234
Chapter 7: 2D Drawing Representation, pg.284
Chapter 8: Section Views, pg.326
Chapter 9: Auxiliary Views, pg.362
Chapter 10: Modeling for Manufacture, pg.414
Chapter 11: Dimensioning, pg.502
Chapter 12: Tolerancing, pg.546
Chapter 13: Threads, Fasteners, and Springs, pg.592
Chapter 14: Working Drawings, pg.636
Chapter 15: Drawing Control and Data Management, pg.710
Chapter 16: Gears and Cams, pg.730
Chapter 17: Electronic Diagrams, pg.756
Chapter 18: Structural Drawing, pg.780
Chapter 19: Landform Drawings, pg.808
Chapter 20: Piping Drawings, pg.828
Chapter 21: Welding Representation, pg.846
Chapter 22: Axonometric Projection, pg.W870
Chapter 23: Perspective Drawings, pg.W900
3. Engineering Drawing & Design, 6th Edition, by David A. Madsen and David P. Madsen (1104 pages), 2017
Chapter 1: Introduction to Engineering Drawing and Design, pg.2
Chapter 2: Drafting Equipment, Media, and Reproduction Methods, pg.39
Chapter 3: Computer-Aided Design and Drafting (CADD), pg.61
Chapter 4: Manufacturing Materials and Processes, pg.109
Chapter 5: Sketching Applications, pg.162
Chapter 6: Lines and Lettering, pg.181
Chapter 7: Drafting Geometry, pg.205
Chapter 8: Multiviews, pg.228
Chapter 9: Auxiliary Views, pg.259
Chapter 10: Dimensioning and Tolerancing, pg.277
Chapter 11: Fasteners and Springs, pg. 347
Chapter 12: Sections, Revolutions, and Conventional Breaks, pg.387
Chapter 13: Geometric Dimensioning and Tolerancing, pg.409
Chapter 14: Pictorial Drawings and Technical Illustrations, pg.495
Chapter 15: Working Drawings, pg.526
Chapter 16: Mechanisms: Linkages, Cams, Gears, and Bearings, pg.561
Chapter 17: Belt and Chain Drives, pg.601
Chapter 18: Welding Processes and Representations, pg.617
Chapter 19: Precision Sheet Metal Drafting, pg.644
Chapter 20: Electrical and Electronic Drafting, pg.669
Chapter 21: Industrial Process Piping, pg.717
Chapter 22: Structural Drafting, pg.773
Chapter 23: Heating, Ventilating, and Air-conditioning (HVAC) and Pattern Development, pg.847
Chapter 24: Civil Drafting, pg.899
Chapter 25: The Engineering Design Process, pg.950
Engineering Drawing and Design Student Companion Website, pg.973
4. Engineering Design and Graphics with SolidWorks by James D. Bethune (829 pages), 2017
Chapter 1: Getting Started, pg.1
Chapter 2: Sketch Entities and Tools, pg.41
Chapter 3: Features, pg.123
Chapter 4: Orthographic Views, pg.225
Chapter 5: Assemblies, pg.299
Chapter 6: Threads and Fasteners, pg.375
Chapter 7: Dimensioning, pg.439
Chapter 8: Tolerancing, pg.509
Chapter 9: Bearings and Fit Tolerances, pg.605
Chapter 10: Gears, pg.639
Chapter 11: Belts and Pulleys, pg.699
Chapter 12: Cams, pg.725
Chapter 13: Projects, after pg.774
5. Interpreting Engineering Drawings, 8th Edition, by Theodore J. Branoff (530 pages), 2016
Unit 1: Introduction: Line Types and Sketching, pg.1
Unit 2: Lettering and Title Blocks, pg.11
Unit 3: Basic Geometry: Circles and Arcs, pg.15
Unit 4: Working Drawings and Projection Theory, pg.22
Unit 5: Introduction to Dimensioning, pg.39
Unit 6: Normal, Inclined, and Oblique Surfaces, pg.52
Unit 7: Pictorial Sketching, pg.67
Unit 8: Machining Symbols and Revision Blocks, pg.78
Unit 9: Chamfers, Undercuts, Tapers, and Knurls, pg.86
Unit 10: Sectional Views, pg.91
Unit 11: One- and Two-View Drawings, pg.110
Unit 12: Surface Texture, pg.117
Unit 13: Introduction to Conventional Tolerancing, pg.130
Unit 14: Inch Fits, pg.142
Unit 15: Metric Fits, pg.150
Unit 16: Threads and Fasteners, pg.161
Unit 17: Auxiliary Views, pg.181
Unit 18: Development Drawings, pg.190
Unit 19: Selection and Arrangement of Views, pg.196
Unit 20: Piping Drawings, pg.202
Unit 21: Bearings, pg.214
Unit 22: Manufacturing Materials, pg.220
Unit 23: Casting Processes, pg.232
Unit 24: Violating True Projection: Conventional Practices, pg.249
Unit 25: Pin Fasteners, pg.264
Unit 26: Drawings for Numerical Control, pg. 274
Unit 27: Assembly Drawings, pg.280
Unit 28: Structural Steel, pg.289
Unit 29: Welding Drawings, pg.294
Unit 30: Groove Welds, pg.305
Unit 31: Other Basic Welds, pg.315
Unit 32: Spur Gears, pg.328
Unit 33: Bevel Gears and Gear Trains, pg.337
Unit 34: Cams, pg.347
Unit 35: Bearings and Clutches, pg.353
Unit 36: Ratchet Wheels, pg.362
Unit 37: Introduction to Geometric Dimensioning and Tolerancing, pg.368
Unit 38: Features and Material Condition Modifiers, pg.380
Unit 39: Form Tolerances, pg.394
Unit 40: The Datum Reference Frame, pg.402
Unit 41: Orientation Tolerances, pg.415
Unit 42: Datum Targets, pg.432
Unit 43: Position Tolerances, pg.440
Unit 44: Profile Tolerances, pg.461
Unit 45: Runout Tolerances, pg.469
6. Architectural Graphic Standards Student Edition, 12th Edition, by The American Institute of Architects (689 pages), 2017
Chapter 1: Functional Planning, pg.3
Chapter 2: Environment, pg.31
Chapter 3: Resilience in Buildings. Pg.53
Chapter 4: Architectural Construction Documentation, pg.77
Chapter 5: Concrete, pg.93
Chapter 6: Masonry, pg.107
Chapter 7: Metals, pg.125
Chapter 8: Wood, pg.141
Chapter 9: Glass, pg.165
Chapter 10: Element A: Substructure, pg.176
Chapter 11: Element B: Shell, pg.203
Chapter 12: Element C: Interiors, pg.363
Chapter 13: Element D: Services, pg.427
Chapter 14: Element E: Equipment and Furnishings, pg.517
Chapter 15: Element F: Special Construction, pg.565
Engineering graphics and design is a combined creative activity aimed at producing engineering structures or outcomes that are useful to people and society. The graphic description of any engineering structure has to be clear and presentable, and in such a form that can be easily understood and constructed or built without much assistance from the designer.
What is Engineering Design?
Engineering design is the type of design practiced by engineers. Engineering design is different from planning because in planning—unlike in engineering design—expressions or presentations are not sufficiently complete or detailed enough to be built like final and complete designs can.
Application of scientific principles is the major thing that distinguishes engineering design from the type of design practiced by other professions: the major difference between engineering graphics and design, and the type of design practiced by other disciplines/professions is that, prior to construction, engineers use the principles of science to prove or demonstrate to an appreciable extent whether designs will work.
With a great degree of accuracy, scientific principles can be used to predict the behavior of physical systems—this is where engineering design comes in. When applying engineering design, planned systems do not have to be real; however, they may have to be clearly and precisely described in mathematical terms.
In many fields of engineering, one of the most important goals of design is to ensure that all structures (bridges, buildings, automobiles, and aircraft) are capable of carrying loads and forces without failing or collapsing.
In order to determine whether a given bridge or building can withstand forces without failing, existing mathematical models have to be employed in making checks and assessments—this is design. Loads are expressed in mathematical terms, and relevant scientific principles (such as Newton’s laws and Hooke’s law) are used to estimate the stresses that would likely be produced in a structure whenever it is acted upon by various weights of loads or forces which could include human beings, chairs, tables, wind, etc.
By comparing the estimated stresses with the limiting values of the strengths of materials expected to be used, it can be determined whether or not any structure can perform certain functions. Engineering design is usually combined with engineering graphics in order to make important and precise descriptions of the geometric and material properties of structures.
Without employing the principles of science, another way to determine whether a structure under design can perform its intended function, is to build it, test it, and hope for the best.
But in most cases, this is not a recommendable option because it doesn’t follow any tested and trusted guidelines like the fields of engineering do. Generally, the principles of science have an upper hand when it comes to design because they are based on past research and proven theories.
Before introducing technical drawing with engineering graphics into the scheme of planned construction, engineering designs have to be carefully validated (proven that they are in accord with important and applicable design criteria) in order to ensure that the most important concerns have been addressed, and intended structures will perform their functions after being built or constructed in accordance with design.
Application of Technical Drawing with Engineering Graphics in Engineering Design
Technical drawing with engineering graphics has two major roles in practical engineering design processes:
To help communicate or pass on information in an easy and understandable way between participants of engineering design processes.
To help designers create better ideas when validating design outcomes or decisions.
It is important to note that in engineering practice, all graphics/drawings remain just a means to an end—successful construction and operation of structures. Generally, engineering graphics are created to serve and support design processes, which in turn assist in the construction of structures that serve greater purposes in society.
It is in this regard that engineering graphics is significantly different from artistic drawings that are created by artists. Unlike engineering drawing, the intention of most artistic drawings to create visually or aesthetically appealing effects.
In many cases, engineering designers do not build or construct their designs or works; for example, many engineering works are usually constructed or built by contractors who work independently of designers.
This implies that there is need to communicate effectively via drawings which can clearly and suitably describe what has been designed in order to be constructed or built. Due to the fact that engineering works are usually large and spacious, many objects are scaled-down and graphically communicated in two- and three-dimensions respectively—i.e., in 2-D & 3-D.
Most times, the complete and final graphics of objects are issued at the end of engineering design processes, and provide complete descriptions of objects that would be constructed or built.
Engineering graphics can also be used to communicate internally within an organization that designs structures; for instance, communication can be from one designer to another, or from a designer to drafting staff.
Note
In order to effectively apply technical drawing with engineering graphics in any design process, engineers or students should be able to produce various types of drawing, formally, and informally. Generally, all drawings help the imagination to create and develop new ideas.
Engineering graphics can be defined as a graphical language that gives precise pictorial expressions of engineering structures and is used to make communication possible between designers and other people who might not necessarily be engineering professionals. Engineering graphics, which usually provides details that cannot be derived from engineering calculations, helps to convey ideas to people, and convert concepts into reality if drafts, illustrations or drawing follow universally accepted codes, criteria, and conventions.
Definition of Graphical Engineering
Graphical engineering can be defined as the branch of engineering that deals with the study of computer-aided design (CAD) and imaging software aimed at creating digital sketches of engineering models, structures, plans, and projections for beneficial purposes. In addition, graphical engineering combines the knowledge of technical drawing with engineering graphics, and computer software and hardware to illustrate and manipulate engineering data/content for practical purposes.
It is quite common for graphical engineering students to study programming languages, 3-D maths, programming interfaces (API) used in building 3-D engines, rendering systems for 2-D and 3-D visuals, machine drawing & design, rapid prototyping, computer-aided drafting, computer-aided design (CAD), AutoCAD, 3-D modeling & parametric design, tooling drawing & design, industrial Management, etc.
This article defines technical drawing (drafting or projection) and uses different images to illustrate the meaning, and types of technical drawing widely taught in schools and practiced in industries. The eBook/technical drawing PDF document for this article is available for free download at the end of the article (along with a list of world-class technical & engineering drawing/graphics books in electronic form/PDF, available for sale at cheap prices). Both the article and eBook discuss the following topics:
1.0 Definition of technical drawing
2.0 Types of technical drawing: parallel projection (orthographic: first angle, and third angle; oblique: cavalier, and cabinet; axonometric: isometric, dimetric, and trimetric), and perspective projection (1-point, 2-point, and 3-point)
3.0 Objectives of technical drawing
4.0 Purpose of technical drawing
5.0 Application of technical drawing
1.0 Definition of technical drawing
Technical drawing can be defined as the graphic representation of an object, concept, or idea using a universal language that consists of graphic symbols produced with the aid of drawing equipment/tools that can be used to measure straight and curved lines according to specified dimensions, scales, and codes of practice.
Technical drawing is used in many professions (engineering, architecture, manufacturing, construction, estate management, etc.) to draw or draft ideas and different views of physical objects like drainages, culverts, septic tanks, incinerators, houses, etc. Drawing—either artistic or technical—is one of the oldest forms of communication, and is believed to be older than verbal communication. Generally, there are two types of drawings: artistic drawing, and technical drawing:
Artistic drawing
Artistic drawing is the type of drawing that is abstract because its meaning is unique to the person/artist who creates it. In order to understand the meaning of an artistic drawing, one has to understand the artist’s point of view or motivation for producing a particular artistic drawing.
Sometimes, it is necessary to understand an artist in order to understand their artistic drawing because artists often take a unique/abstract approach when communicating through their drawings. This type of approach gives rise to various interpretations when their drawings are exposed to public view.
Regardless of how complex artistic drawings may appear, they express the clear feelings, beliefs, philosophies, and ideas of the artists who create them. Artistic drawings are generally freehand drawings or drawings made without the use of drawing instruments/tools.
Technical drawing
Technical drawing is the type of drawing that is not abstract because it doesn’t require an understanding of what its creator has in mind; rather, it requires an understanding that can only be gained by studying and using universally accepted tools, codes, and conventions applicable to technical drawing.
In addition to the previously stated definition of technical drawing, we can say that technical drawing clearly, precisely, and concisely communicates all important information conveyed by an idea produced in graphic form by the use of universally accepted codes of practice, tools, dimensions, notes, symbols, and specifications.
Technical drawing can be done manually on paper, or technologically on computers. When any idea or object is drawn on a computer, it is said to be drafted by computer-aided design (CAD). One major advantage of using CAD is that revisions can be easily and speedily carried out on any draft.
Any student, architect, engineer, etc., must understand the theory behind projections, dimensioning, and conventions if they wish to become proficient in drafting and interpreting drafts. It is very important for people to understand manual (traditional) drawing/drafting before exposing themselves to CAD softwares. Why? Because an understanding of manual drawings would make it easier to use CAD.
2.0 Types of technical drawing
Technical drawings are constructed on the basis of the fundamental principles of projection. There are two main types of technical drawing or projection: parallel projection, and perspective projection. (Note that each projection has various categories which will be illustrated further below.)
A projection is any drawing, draft, or representation of an idea or object that is carried out after considering views from various imaginary planes. Projections, which are quite similar to the direct views that one can see on televisions, can be used to represent actual objects if the following are employed:
the eye of the viewer looking at the object.
an imaginary plane of projection as dictated by the direction of the eye(s) of the viewer.
projectors or imaginary lines of sight.
The theories behind projection have been widely used to draft 3-dimensional objects on 2-dimensional media such as papers and computer screens. The theory of projection is based on two variables:
line of sight.
plane of projection: plane from which images can be projected—depending on the axis.
Figure 1: Lines of sight: parallel, and perspective projections
Figure 2: Planes of projection: parallel, and perspective projections
2.1 Parallel projection
Parallel projection is the type of projection in which the lines of sight or projectors are parallel to each other, and also perpendicular to the planes of objects or images. Parallel projection can be categorized or divided into orthographic, oblique, and axonometric projections.
(1) Orthographic projection
Orthographic projection (or drawing) is the type of projection in which 3-dimensional objects are represented in 2 dimensions by projecting planes (consisting of 2 major axes) of objects so that they are parallel with the plane of the medium they are projected on.
Orthographic projection can also be defined as the type of projection in which views are taken on different planes of objects and drawn (or represented) in 2 dimensions as illustrated by the principal views shown in the figures below:
Figure 3: Three major views in orthographic projectionFigure 4: Six general views in orthographic projection
There are two types of orthographic projection: first angle projection, and third angle projection:
In first angle projection (i.e., European/international system) the front view is placed at the top of a medium (paper, computer screen, etc.) along with the right side view which is placed at the left side of the front view, while the left side view is placed at the right side of the front view, and the plan (T) is placed alone beneath the front view.
In third angle projection (i.e., American system) the plan (T) is placed alone at the top, while the front view is placed beneath the plan, and the right side view is placed at the right side of the front view, while the left side view is placed at the left side of the front view. (Note that third-angle projection is more popular than first-angle projection.)
Figure 5: First angle, and third angle projections
If you would like to read more details about orthographic projection or drawing, click here.
(2) Oblique projection
Oblique projection is the type of projection in which an object is drawn in 3 dimensions, with each of the 3 dimensions (or major planes) consisting of two lines (or major axes: either xy, or yz, or xz) perpendicular to each other (i.e. 90°), and one of the 3 planes parallel to the plane of paper, or computer screen, etc.
In addition, one of the 3 planes is projected at either 30°, 45°, or 60° to the x-axis. Oblique projection is of 2 types: cavalier, and cabinet projection.
Figure 6: Oblique projection: cavalier, and cabinet projections
In cavalier projection, one of the 3 planes is drafted to represent a plane of an object “according to a given scale”, while in cabinet projection, one of the 3 planes is drafted to represent half of a plane of an object “according to half of a given scale”. A scale is any ratio (examples: 1:10, 1:100, 1:1000, etc.) of the size of an object on paper to the actual size of the same object in real life.
Figure 7: Oblique projection of objects expressed in their respective orthographic views
(3) Axonometric projection
Axonometric projection is the type of projection that consists of three-dimensional drawings in which each of the 3 major axes (x, y, and z) of an object is drawn perpendicular to each other by either 30°, 45°, or 60°, and no plane of the object is drawn parallel to the plane of the medium—paper, computer screen, etc. Axonometric projection/drawing can be categorized into three types: isometric, dimetric, and trimetric projections.
Isometric projection is a method of projection/drawing in which the edges of 3-dimensional objects are represented by 3 axes perpendicular to each other and inclined to each other by 120° on the plane of media—paper or computer; also, 2 of the 3 axes are inclined at either 30°, 45°, or 60° to any imaginary x-axis on any medium.
In dimetric projection, 2 angles between any 2 major axes are unequal, while in trimetric projection, the 3 angles between the 3 major axes are unequal. Two different angles are required to construct 2 planes of objects in dimetric projections, while 3 different angles are required to construct 3 planes of objects in trimetric projections.
Figure 8: Isometric, dimetric, and trimetric projections
2.2 Perspective projection
Perspective projection is the type of projection in which objects appear smaller as their distances from an observer increases: objects’ dimensions along a line of sight appear shorter than they actually are.
There are 3 types of perspective projections: 1-point, 2-point, and 3-point projections. One-point perspective projections consist of 1 vanishing point, while 2-point and 3-point perspective projections consist of 2 and 3 vanishing points, respectively.
A vanishing point is a point of convergence where all lines of sight meet.
Figure 9: One-point perspective projection
Figure 10: Two-point perspective projection
Figure 11: Three-point perspective projection
3.0 Objectives of technical drawing
The general objectives of studying technical drawing include the following:
to develop skills in using universally accepted tools, symbols, scales, and conventions to draw any visible object or invisible idea on paper, and computer.
to understand orthographic and isometric projections and employ them in drafting/drawing ideas and objects using both projections, respectively.
to understand and interpret technical drawings, sketches, and working drawings.
to develop the ability to use imagination to observe, visualize and draft objects, ideas, or concepts.
to develop the ability to produce clean, accurate, neat, and informative drawings in a moderate amount of time.
to develop the ability to take on any projects and draw environmental health science, civil, and environmental engineering objects/structures.
4.0 Purpose of technical drawing
To draft and design objects or structures, and assess how they would appear in real life after they are manufactured, fabricated, assembled, constructed, or built. For example, houses, septic tanks, drainages, etc., must be designed and assessed before they are built.
5.0 Application of technical drawing
Technical drawings have wide applications in any field in which planning and designing are required, such as architecture, manufacturing, engineering, construction, environment, estate management, etc.
Sanitarians, surveyors, environmental scientists, and civil/environmental engineers use technical drawings to supervise the construction of layouts, structures, objects, and boundaries for various types of properties (houses, etc.).
Technical drawings are also used in situations where ideas/designs for objects and structures need to be modified, and different 2-dimensional views need to be assembled into 3-dimensional views.
Generally, technical drawings are used by a variety of professions, including but not limited to:
engineers
architects
contractors
inventors
technicians
teachers
etc.
If you are interested in downloading the eBook of this article for free, click here. It contains all the information in this article and extra important information on its last page which has a link to images of hundreds of various shapes and sizes of objects in 2 & 3 dimensions, and categorized under different types of projections.
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The titles of the books (arranged in decreasing order of priority [from 1 to 6]—based on our assessment) and their respective number of pages and titles of chapters are as follows:
1. Technical Graphics Communication, 4th Edition, by Gary R. Bertoline, Eric N. Wiebe, Nathan W. Hartman, William A. Ross (1335 pages), 2009
Chapter 1: Introduction to Graphics Communication, pg.5
Chapter 2: The Engineering Design Process, pg.27
Chapter 3: Design in Industry, pg.46
Chapter 4: The Role of Technical Graphics in Production, Automation, and Manufacturing Processes, pg.109
Chapter 5: Design & Visualization, pg.135
Chapter 6: Technical Drawing Tools, pg.187
Chapter 7: Sketching and Text, pg.237
Chapter 8: Engineering Geometry and Construction, pg.305
Chapter 9: Three-dimensional Modeling, pg.399
Chapter 10: Multiview Drawings, pg.488
Chapter 11: Axonometric and Oblique Drawings, pg.577
Chapter 12: Perspective Drawings, pg.631
Chapter 13: Auxiliary Views, pg.652
Chapter 14: Fundamentals of Descriptive Geometry, pg.691
Chapter 15: Intersections and Developments, pg.716
Chapter 16: Section Views, pg.759
Chapter 17: Dimensioning and Tolerancing Practices, pg.818
Chapter 18: Geometric Dimensioning and Tolerancing (GDT), pg.875
Chapter 19: Fastening Devices and Methods, pg.908
Chapter 20: Working Drawings, pg.949
Chapter 21: Technical Data Presentation, pg.1064
Chapter 22: Mechanisms: Gears, Cams, Bearings, and Linkages, pg.1105
Chapter 23: Electronic Drawings, pg.1146
Chapter 24: Piping Drawings, pg.1163
Chapter 25: Welding Drawings, pg.1187
2. Technical Drawing with Engineering Graphics, 15th Edition, by Frederick E. Giesecke, Shawna Lockhart, Marla Goodman, Cindy M. Johnson (1077 pages), 2016
Chapter 1: The World-wide Language for Graphic Design, pg.2
Chapter 2: Layouts and Lettering, pg.30
Chapter 3: Visualization and Sketching, pg.62
Chapter 4: Geometry for Modeling and Design, pg.124
Chapter 5: Modeling and Design, pg.170
Chapter 6: Orthographic Projection, pg.234
Chapter 7: 2D Drawing Representation, pg.284
Chapter 8: Section Views, pg.326
Chapter 9: Auxiliary Views, pg.362
Chapter 10: Modeling for Manufacture, pg.414
Chapter 11: Dimensioning, pg.502
Chapter 12: Tolerancing, pg.546
Chapter 13: Threads, Fasteners, and Springs, pg.592
Chapter 14: Working Drawings, pg.636
Chapter 15: Drawing Control and Data Management, pg.710
Chapter 16: Gears and Cams, pg.730
Chapter 17: Electronic Diagrams, pg.756
Chapter 18: Structural Drawing, pg.780
Chapter 19: Landform Drawings, pg.808
Chapter 20: Piping Drawings, pg.828
Chapter 21: Welding Representation, pg.846
Chapter 22: Axonometric Projection, pg.W870
Chapter 23: Perspective Drawings, pg.W900
3. Engineering Drawing & Design, 6th Edition, by David A. Madsen and David P. Madsen (1104 pages), 2017
Chapter 1: Introduction to Engineering Drawing and Design, pg.2
Chapter 2: Drafting Equipment, Media, and Reproduction Methods, pg.39
Chapter 3: Computer-Aided Design and Drafting (CADD), pg.61
Chapter 4: Manufacturing Materials and Processes, pg.109
Chapter 5: Sketching Applications, pg.162
Chapter 6: Lines and Lettering, pg.181
Chapter 7: Drafting Geometry, pg.205
Chapter 8: Multiviews, pg.228
Chapter 9: Auxiliary Views, pg.259
Chapter 10: Dimensioning and Tolerancing, pg.277
Chapter 11: Fasteners and Springs, pg. 347
Chapter 12: Sections, Revolutions, and Conventional Breaks, pg.387
Chapter 13: Geometric Dimensioning and Tolerancing, pg.409
Chapter 14: Pictorial Drawings and Technical Illustrations, pg.495
Chapter 15: Working Drawings, pg.526
Chapter 16: Mechanisms: Linkages, Cams, Gears, and Bearings, pg.561
Chapter 17: Belt and Chain Drives, pg.601
Chapter 18: Welding Processes and Representations, pg.617
Chapter 19: Precision Sheet Metal Drafting, pg.644
Chapter 20: Electrical and Electronic Drafting, pg.669
Chapter 21: Industrial Process Piping, pg.717
Chapter 22: Structural Drafting, pg.773
Chapter 23: Heating, Ventilating, and Air-conditioning (HVAC) and Pattern Development, pg.847
Chapter 24: Civil Drafting, pg.899
Chapter 25: The Engineering Design Process, pg.950
Engineering Drawing and Design Student Companion Website, pg.973
4. Engineering Design and Graphics with SolidWorks by James D. Bethune (829 pages), 2017
Chapter 1: Getting Started, pg.1
Chapter 2: Sketch Entities and Tools, pg.41
Chapter 3: Features, pg.123
Chapter 4: Orthographic Views, pg.225
Chapter 5: Assemblies, pg.299
Chapter 6: Threads and Fasteners, pg.375
Chapter 7: Dimensioning, pg.439
Chapter 8: Tolerancing, pg.509
Chapter 9: Bearings and Fit Tolerances, pg.605
Chapter 10: Gears, pg.639
Chapter 11: Belts and Pulleys, pg.699
Chapter 12: Cams, pg.725
Chapter 13: Projects, after pg.774
5. Interpreting Engineering Drawings, 8th Edition, by Theodore J. Branoff (530 pages), 2016
Unit 1: Introduction: Line Types and Sketching, pg.1
Unit 2: Lettering and Title Blocks, pg.11
Unit 3: Basic Geometry: Circles and Arcs, pg.15
Unit 4: Working Drawings and Projection Theory, pg.22
Unit 5: Introduction to Dimensioning, pg.39
Unit 6: Normal, Inclined, and Oblique Surfaces, pg.52
Unit 7: Pictorial Sketching, pg.67
Unit 8: Machining Symbols and Revision Blocks, pg.78
Unit 9: Chamfers, Undercuts, Tapers, and Knurls, pg.86
Unit 10: Sectional Views, pg.91
Unit 11: One- and Two-View Drawings, pg.110
Unit 12: Surface Texture, pg.117
Unit 13: Introduction to Conventional Tolerancing, pg.130
Unit 14: Inch Fits, pg.142
Unit 15: Metric Fits, pg.150
Unit 16: Threads and Fasteners, pg.161
Unit 17: Auxiliary Views, pg.181
Unit 18: Development Drawings, pg.190
Unit 19: Selection and Arrangement of Views, pg.196
Unit 20: Piping Drawings, pg.202
Unit 21: Bearings, pg.214
Unit 22: Manufacturing Materials, pg.220
Unit 23: Casting Processes, pg.232
Unit 24: Violating True Projection: Conventional Practices, pg.249
Unit 25: Pin Fasteners, pg.264
Unit 26: Drawings for Numerical Control, pg. 274
Unit 27: Assembly Drawings, pg.280
Unit 28: Structural Steel, pg.289
Unit 29: Welding Drawings, pg.294
Unit 30: Groove Welds, pg.305
Unit 31: Other Basic Welds, pg.315
Unit 32: Spur Gears, pg.328
Unit 33: Bevel Gears and Gear Trains, pg.337
Unit 34: Cams, pg.347
Unit 35: Bearings and Clutches, pg.353
Unit 36: Ratchet Wheels, pg.362
Unit 37: Introduction to Geometric Dimensioning and Tolerancing, pg.368
Unit 38: Features and Material Condition Modifiers, pg.380
Unit 39: Form Tolerances, pg.394
Unit 40: The Datum Reference Frame, pg.402
Unit 41: Orientation Tolerances, pg.415
Unit 42: Datum Targets, pg.432
Unit 43: Position Tolerances, pg.440
Unit 44: Profile Tolerances, pg.461
Unit 45: Runout Tolerances, pg.469
6. Architectural Graphic Standards Student Edition, 12th Edition, by The American Institute of Architects (689 pages), 2017
Chapter 1: Functional Planning, pg.3
Chapter 2: Environment, pg.31
Chapter 3: Resilience in Buildings. Pg.53
Chapter 4: Architectural Construction Documentation, pg.77
Chapter 5: Concrete, pg.93
Chapter 6: Masonry, pg.107
Chapter 7: Metals, pg.125
Chapter 8: Wood, pg.141
Chapter 9: Glass, pg.165
Chapter 10: Element A: Substructure, pg.176
Chapter 11: Element B: Shell, pg.203
Chapter 12: Element C: Interiors, pg.363
Chapter 13: Element D: Services, pg.427
Chapter 14: Element E: Equipment and Furnishings, pg.517
Chapter 15: Element F: Special Construction, pg.565
Figure 10: Drawing board and drawing paper
Figure 13: T-square
Figure 14: Drawing compasses (for drawing circular and elliptical shapes)
Motivation & Environment 