Introduction and CAD Overview

Just the Beginning

Disclaimer & Copyright

All care has been taken to ensure the accuracy of the information contained in this course, however no warranty expressed or implied is given that this information is either current or accurate and should not be relied on for any purpose.

No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording or by any information or storage retrieval system, without express permission in writing from CAD International.

Copyright© 2020 CAD Australia Pty Ltd trading as CAD International. All Rights Reserved.

Prerequisites

We assume you already know the basics of how to use a computer and that you have internet access. Your computer is capable of running the software successfully and your mouse has a scroll wheel on top. (Apple Magic Mouse® or notebook touchpads are not supported)

Windows® & Mac®

This course was authored on a Windows® PC. Mac® users may need to transpose references to Windows® keyboard shortcuts. E.g. Alt = Option, Ctrl = Command. Where possible we have put Mac® specific keys in BLUE italics.

Marking & Assessment

If you’re doing this course as a certificate course directly with CAD International, you’ll need to email your quizzes and drawing exercises for marking by CAD International-certified tutors. Submit these to support@cad.com.au

Have Fun, Step by Step

This course is planned with your success in mind. Resist the urge to skip the foundation exercises.

We’ve used light-hearted, fun examples in this course to help you fully grasped the concepts and ideas before you apply them to the serious nature of your design business. Your memory will recall more easily when you’re having fun.

Mistakes

If you should find a mistake in the content of this course please notify info@cad.com.au straight away so we can rectify the error and make your learning experience “better, faster, funner®”

Caves to CAD

As far back in human history as we can discover, the art of drawing has been used to communicate the world around us. From markings in the sand to rock carvings, mankind has been able to translate what he sees into a two-dimensional representation on some form of surface.

As we evolved, both our real world and our imagination was drawn or painted. Our visual impressions laid out onto a 2D surface to communicate what was in the one person’s imagination to another who could then build it. This became even more important when the construction or development of an idea involved more than one person. The entire team needed to be reading, translating and modifying the drawings in a collaborative design scenario.

Engineers, inventors, architects, artists, designers, scientists and creative minds throughout time have turned to pen or pencil and paper to get their ideas seen and understood, and for thousands of years, apart from the invention of the articulated drawing machine and drawing board this remained almost unchanged – then arrived C.A.D.

CAD is an anagram for Computer Assisted Design or Computer Aided Drafting and was adopted by designers in the 1980’s when the mass adoption of the personal computer (PC) changed almost every aspect of our lives. CAD is arguably the most significant design breakthrough of all time.

Just like the pencil, CAD is a tool that a designer can use to translate ideas back and forth to his own brain or to others in the creative process, but unlike a pencil it has a whole range of distinct advantages that assist the designer to save time and effort. The most common of these advantages are accuracy, duplication and editing.

Vector vs. Raster

Unlike regular drawings done by hand or when using other computer graphic processes, CAD is precise and can be scaled with no loss of accuracy.  This is because CAD uses a mathematical way to describe the lines in the drawing known as Vector graphics whilst other programs such as image or photo editing programs use Raster graphics.

Raster (also known as Bitmap) graphics interprets the world as a series of dots that the human eye merges in order to form a realistic image. Printers, TV and computer screens rely on this process to convince us that what we see is real, but if you were to look closely you would see that a line is in fact nothing more than a jagged set of dots. To lengthen a line, you would have to add more dots and to shorten you would have to remove dots. The big problem comes when you have to represent real world objects in real size as a series of dots, there are just too many dots to manage and the accuracy is only as good as the size of a single dot. If you’ve ever zoomed in to a digital photo you can see the dots and the jagged or grainy image.

Vector graphics on the other hand define lines using numerical values. A straight line for instance is defined by two end points with absolute positions in space. Lines, arcs, circles, text, etc. are complete objects and not just a series of dots. If you zoom in to a line created in Vector based software it remains continuous, stepped visually only by the dots on your screen or printer’s output resolution.

A vector line could be imagined as being a piece of string stretched between two points. If you move the end points the string follows and is repositioned. A raster line can be imagined as a stack of bricks. You have to move every brick to change the direction or position.

<!– –>

CAD software is a special type of Vector program. It allows you to work in real-life measurements. So, if a wall is 10 meters long then you can specify 10 meters (or 10,000mm) when you draw the wall. The software will automatically take care of the drawing scale to reduce or enlarge your drawing to your desired size without affecting the actual dimensions of the objects you’ve drawn.

Modern CAD software lets you to include raster images in the CAD drawing as well as your accurate Vector line work. This means you can include photographs and artwork in your CAD communication.

Knowledge

Just as the word Xerox® is used in the USA to refer to photocopying and a Hoover® is used in the UK to refer to a vacuum cleaner, AutoCAD® is often (incorrectly) used to refer to all CAD software, but it clearly isn’t.
‘CAD’ is not a product or brand but a generic term that encompasses hundreds of software programs dedicated to assisting designers and technical drafters in many industries.
Forgive those who don’t know this fact and feel free to educate them!

Why CAD?

For those of you that can draw beautiful drawings using pen and paper you may be asking ‘why do I need to use CAD at all?’ The answer is simple…

  1. Accuracy. CAD is incredibly accurate and when used correctly provides precision 2D drawings and 3D models that ensure processes like building and manufacturing are dimensionally error free.
  2. Consistency. Whether you feel like drawing that day or not, or when you have multiple designers and drafters in your office CAD allows you to maintain a set of clear office standards in every drawing.
  3. Speed. CAD lets you draw faster and make changes to designs in an instant. When used correctly a single design change can be reflected automatically in every drawing with no extra effort.
  4. Compatibility. By sharing files between you and your associates you can benefit directly from the work already done by others. For instance, a Landscape Architect or Designer can use the CAD drawings from a surveyor or Architect without needing the redraw from scratch.
  5. Safe storage. CAD drawings take up no physical space, and can be backed up off site in case of fire or disaster.
  6. Quantities. Take-offs can be performed on CAD drawings and models that allow for rapid more accurate costing of designs
  7. Downstream activity. By using CAD, you can create a virtual model of your designs that can then be used by many downstream processes. E.g. Engineering can test your models for strength, flexibility, functionality using other software that can read your CAD files. Designs can be checked for appearance, weight, and accuracy of fit. In Architecture the CAD models can become Building Information Models (BIM) and be checked for heat loss, wind resistance, and maintenance scheduling. CAD models can also become real 3D objects using emerging 3D printing techniques.
  8. Appearance. Your drawings have a better chance of being clean, neat and easy to read.
  9. Enjoyment. CAD should be a lot of fun. It is an extension to the designer’s creative process and provides a powerful way to get thoughts and ideas into reality.

Concepts

In this section we look at some important concepts used in almost every CAD program and we’ll also cover some CAD terminology.  Don’t be concerned if you don’t understand 100% of the information immediately. You’ll ‘catch-on’ as you begin to use the software.

Drawings and Models

Because the software we’re using in this course lets you create 2D drawings as well as 3D models in the same space, we’ll use the terms ‘draw’ and ‘model’ interchangeably.

Coordinates

We’ve already explained that CAD is vector based and this is important because CAD relies on its ability to draw accurately using numeric coordinates in space rather than dots on a page. In all CAD software there’s a coordinates system based on the idea that somewhere, a place called ‘absolute zero’ or ‘model zero’ exists. This is where all coordinates are measured from and it usually has a symbol on screen that represents its position. Typically, you’ll see this symbol as a set of ‘L’ shaped X and Y labelled pointers.

Two dimensional coordinates are usually expressed as values in the ‘X’ and ‘Y’ direction. In 3D there are also coordinates on the ‘Z’ axis.

Model Space

The next concept is that the space you’re working in is infinite and not a limited size piece of paper. You could draw something as small as an atom or as large as the solar system. Size doesn’t matter!

Zoom

To fit very large or very small models onto your screen, CAD software allows you to move closer or further away from the drawing. This is called Zooming and it works in the same way as a zoom lens on a camera. The size of the model itself doesn’t change – only how big it looks on screen.

Scale

A drawing is a representation of the real thing, usually at an enlarged or reduced size so that it can fit on a sheet of paper and be printed. This is known as drawing to scale. CAD lets you draw at an objects real size (1:1) and will automatically shrink or enlarge views of that object to fit within a defined window (Viewport) on your sheet (Layout).

E.g. (1:100), (1inch = 1ft), (½” = 1ft), (1:1000) etc.

Most industries work with common scale values to make it easier to compare one drawing with another or to measure off of the printed drawing with a ‘scale rule’

Pan / Scroll

Moving left, right, up or down around the screen is known as Panning or Scrolling. It allows you to work on any part of the drawing by sliding the desired area of the drawing into view.

Files

The drawings are stored in your computer as files. File names usually have two parts, the name itself followed by an extension to the name. The file extension is usually made up of three letters and these identify what format or language the file is stored as.

Different CAD programs use different formats, for example Drawing001.DWG, Drawing001.CAD, Drawing001.DXF, Drawing001.DGN, Drawing001.PRT etc. In this program the file extension is .CAD

Tech Tip

Your computer may be set to hide the file extensions so you can’t see them. Switching them on will make it easier to identify what types of files you’re working with

Layers

Layers are an important concept in CAD software. Every drawing is made up of a number of Layers on which you place your entities.

For the purpose of 2D drawings, layers can be thought of as a series of clear sheets all stacked on top of each other with separate sets of information.

Layers are used as a way of segregating the information in your drawing so you can visibly switch information on or off and can selectively pick the entities you want to work with without picking the ones you don’t.

Layers are numbered from 0 – 2047 and can also be named and grouped to make them easier to work with. A well organised drawing will be separated into layers, each with its own purpose.

Only one layer can be active to draw on at any one time.

Entities

CAD works with the idea that the elements you insert into your drawing are unique objects known as ‘entities’.

Entities are not ghostly creatures but refer to all the bits that make up a drawing.

A straight line is an entity, an arc is an entity, a circle is an entity, text is an entity, a symbol is an entity, an area of hatching is an entity, a dimension is an entity, an image file is an entity and so on.

Note

This software allows you to have any number of colours, line styles and line thicknesses on each layer. This means you don’t need too many layers to keep your drawing organised. It also means your layers are not locked into a single colour, style or weight