ABOUT CAD

Computer-aided design (CAD), also known as computer-aided drafting (CAD) or computer-aided design and drafting (CADD), is the use of computer systems to assist in the creation, modification, analysis, or optimization of a design .CAD is an important industrial art extensively used in many applications, including automotive, shipbuilding, and aerospace industries, industrial and architectural design, and many more. CAD is also widely used to produce computer animation for  special effects in movies,advertising and technical manuals.  Because of its enormous economic importance, CAD has been a major driving force for research in computational geometry, computer graphics (both hardware and software), and discrete differential geometry.

Current computer-aided design software packages range from 2D vector--based drafting systems to 3D solid and surface modelers. Modern CAD packages can also frequently allow rotations in three dimensions, allowing viewing of a designed object from any desired angle, even from the inside looking out. Some CAD software is capable of dynamic mathematical modeling, in which case it may be marketed as CADD.

CAD has become an especially important technology within the scope of computer aided technologies, with benefits such as lower product development costs and a greatly shortened design cycle. CAD enables designers to layout and develop work on screen, print it out and save it for future editing, saving time on their drawings.

CAD Software's

• Auto CAD http://en.wikipedia.org/wiki/AutoCAD

• CADian     https://www.cadian.com/english/index.asp

• ArchiCAd  http://en.wikipedia.org/wiki/ArchiCAD

• Revit         http://en.wikipedia.org/wiki/Autodesk_Revit

• Pro Engineer http://en.wikibooks.org/wiki/Pro_Engineer

• CATIA     http://en.wikipedia.org/wiki/CATIA

• Inventor  http://usa.autodesk.com/autodesk-inventor/

• Solid Edge http://en.wikipedia.org/wiki/Solid_Edge

• Solidworks http://en.wikipedia.org/wiki/SolidWork

What Is CAD?

CAD stands for Computer Aided Design. It is a combination of hardware and software combinationswhich have revolutionized the way designers work. Speed and efficiency have increased, as well as ease of communication. For example,working drawings could be time consuming and any revisions even more so. CAD has not only reduced the time spent drafting to a fraction of what it used to be, but any changes in the drawing can also be done quickly without having to redraw everything. Moreover, different views can be easily created using the same drawing. Although designers use CAD to produce beautifully layered graphic work, perspectives and walkthrough animations, even test a design before implementation, there are times when CAD drawings lack the human emotional content seen in hand drawings.

Generalized Design Process Includes

-         Customer Order

-         Problem Definition(Initial Design)

-         Geometric Modeling

-         Engineering Analysis

-         Design Evaluation

-         Production And Marketing

Main Applications of Computer Aided Design (CAD)

Drafting Detailing
This process is used to create the 2D drawings of components or assemblies; usually directly  from a 3D model, although 2D CAD can create 2D drawings directly.
Solid Modeling

This process is used to create solid components of desired shape by joining and cutting

different solid volumes. The final solid model is a virtual replica of an actual product but

it can be seen and rotated like a real product.

Surface modeling

This process is used to create surfaces of desired shape by trimming, stitching and

Joining different surfaces to create a final shape model.

Assembly

This process is used to assemble the models created in solid or surface modeling to

Create a final assembly. This is used to see the actual fitment of all models and see the

actual working of assembly.

Reverse Engineering

This process is used to convert the real component into 3D CAD Model. Different types

of instruments such as laser scanner, white light scanner, CMM (coordinate measuring

Machine) etc. are used to measure or decode the shape of real model. The virtual

Model obtained can then be modified in a CAD program

Auto CAD Made Simple

Lets Learn Auto CAD

  Before you begin to use the software, you need to become familiar with the interface and some of the
  core functionality and features.

Navigating the Working Environment

The working environment and the types of interface elements that you must
become familiar with if you are to become proficient in the software.Before you begin creating drawings, you should familiarize yourself with the interface

1. Application Menu
2. Quick Access Toolbar
3. Info center
4. Title Bar
5. Ribbon
6. Drawing Area
7. Crosshairs
8. Command Window
9. Status Bar

1.  Application Menu

You can use the Application Menu to access several key commands such as New, Open,                                                                                Save, Print, and Close. Most of these commands lead to sub menus that give you more detailed options.

2. Quick Access Toolbar

Store commands that you frequently access in AutoCAD. By default, you can access New, Open, Save, Plot, Undo, and Redo from the Quick Access toolbar. Add commands to the Quick Access toolbar using the shortcut menus of all commands on the ribbon, menu browser, and toolbars.

3. Info Centre

Search for information through keywords or phrases, display the Communication Center panel for product updates and announcements, or display the Favorites panel to access saved topics. You can also receive information from RSS feeds to which you subscribe, or feeds published by your CAD manager.

4. Title Bar

In addition to housing the Application Menu button, the title bar contains the Quick                                                        

Access toolbar and the Info Center.

5. Ribbon

On the top of the AutoCAD window, just below the title bar, is a wide area called the Ribbon.

 It provides easy access to many AutoCAD tools with tabs, panels, and buttons.

   In AutoCAD, a panel is a grouping of buttons for  In the Home tab of the Ribbon, the Draw,

   Modify, LayersAnnotation, Block, Properties, Groups, Utilities, and Clipboard panels are

displayed.

6. Drawing Area\Graphical Area

    The graphical area is the area of the interface where your drawing is shown. There are two  

Scroll bars, one on the right side (vertical) allow you to scroll the diagram vertically.And

The other at the bottom (horizontal) allows you to scroll the diagram horizontally

7. Crosshair

   As you move the pointing device in the drawing area, notice that the pointer becomes a special cursor

Called the crosshairs. You will use the crosshairs to pick points and select objects in the drawing area. 

.  When you move outside the drawing area, the normal Windows pointer appears.

8. Command Window

    Notice the Command Line window near the bottom of the screen. you can enter AutoCAD   commands at the Command line window. However, in many cases, it is faster and easier to use buttons on the Ribbon and on toolbars, or to use dynamic input.

9. Status Bar

   View the coordinate values of your cursor, and access several buttons for turning drawing   tools on and off, as well as many display tools used to scale annotations

SELECTION METHOD IN AUTOCAD

Before you learn how to use modifying tool bar in Autocad.You need to know something about object          selection.As your drawing grows in complexity and contains more objects, you need to use different  selection methods to select these objects efficiently.

Before You start use AutoCAD modify commands you need to know something about object selection methods.All of the modify command require that you make one or more object selections.

The different methods are:-

1.Pick Single

You can pick single object when AutoCAD ask you to select objects.

2. Window

one can define a window selection by clicking at two points. Click first point on the left side, and 2nd point on the right side. This will select all elements inside the window.

3. Cross Window

   Basically if your window selection defined from right to left, then it will be cross window selection. It will select all elements inside and touching the window.

4. Fence

  You can select drawing elements by defining ‘a fence’ that touched objects you wanted. Just type F then [enter] to activate it. After you finish defining your fence, press [enter] to select.

5. Window Polygon

This option behaves as window selection, but you can define unlimited points for that window. Just type WP then [enter] to activate it. All elements inside the window will be selected.

6. Crossing Polygon

 Similar to cross window selection.Activated by entering CP command.

7. Touching Objects

 When AutoCAD ask you to select object, type ‘FS then [enter]. We use ‘for transparent   use.Pick your object, and then all objects touching it will be selected.

8. Cycle Overlapping Objects

  If you have many overlapped drawing elements or close to each other, and you are too lazy to zoom in, you can cycle between them by pressing [shift] + [space]. Hold your [shift] key, and press [space] several times until you found your object. Release your keyboard key, and then click your mouse.

9. Select Previous or Last Objects

Did you ever want to select your previous selection?  Easy, just type P then [enter] when AutoCAD ask you to do selection.

What about last object created? Either the last drawn or result from modify operations such as copy. Type L then [enter].

10. Remove/Add

    Sometimes it’s easier to select all elements then remove some of them from your selection    set. You can do this by holding [shift] and select object you want to exclude. OR, you can type R  then [enter] to switch to remove mode.

To activate add objects, type A then [enter].

11. Lasso selection

This feature is introduced in AutoCAD 2015. You can click and hold your left mouse then drag the pointer to make a lasso selection. Similar to window and crossing polygon, but you don’t need to type anything to activate this mode. If you drag your pointer first to the right, it will be a window selection. But if after the first click you drag it to the left, it will be crossing window selection. Like you see below.

  Selecting the objects by picking

 

The most obvious way to select an object in AutoCAD is simply to pick it.Generally all you have to do is place your cursor over an object, click the mouse button and the object will be selected.

 

 Using a Window to Select Objects

 

 Selection sets are useful when you want to modify a number of objects. You can create a selection set
either before or after activating the pertinent command.

 

 Implied Window Selection

 

 
An implied window is a method of selecting objects by creating a selection window around those
objects. To select objects using an implied window, click in a blank area of the drawing then drag
the cursor from left to right and click the opposite corner of the selection window. Objects enclosed
completely within the implied window will be selected.

•  Only objects that are entirely within the rectangular window are selected.

•  If any part of an object is outside the window, that object is not selected.

•  Although the drag movement must be from left to right, it can also be up and across, or down and across the drawing area. The drag movement shown here is up and across.

•  The window selection area has a solid outline and a differently colored shading to distinguish it from that used in a crossing selection.

•  The shaded area indicates the points in space used to define the corners of the rectangular Window.

   Manual Window Selection

You can define a selection window by using the Window selection method. In response to any Select
Objects prompt, enter W and press ENTER. This enables you to create a regular selection window in
which you are not restricted as to the direction of the cursor movement when defining the points.
When you specify the Window option, you can define the window from left-to-right or right-toleft,
and it always results in a regular selection window. Only objects that are completely within the
selection window will be included in the selection set.

  Implied Crossing Selection

Implied crossing means that you have not manually specified a specific selection method. To make a
crossing selection, you specify opposite corners that define a rectangular area. The first corner point
must be in your drawing area, but cannot be touching any existing objects. After specifying the first
corner point, you drag the cursor from right to left to create a crossing selection that is in the opposite
direction of the previous Window selection.

• All objects that are within or touched by the rectangular crossing window are included in the   selection set.

• Although the drag movement must be from right to left, it can be up and across or down and across the drawing area.

• The crossing window has a dashed outline and a differently colored shading to distinguish it from that used in a window selection.

•  The shaded area indicates the points in space that were used to define the corners of the rectangular window.

    Manual Crossing Selection

You can define a non-implied Crossing Window by using the Crossing Window selection method.
In response to any Select Objects prompt, enter C and press ENTER. This enables you to create a
Crossing selection window where the direction of the cursor movement is not restricted when you
define the points. When you specify Crossing Window, you can define the window from left to right or
right to left, and it always results in a Crossing selection window.

Setting The Workspace

What is Workspace?

A workspace is a task-oriented drawing environment oriented in such a way as to
provide you with only the tools and interface elements necessary to accomplish the tasks relevant to
that environment.

AutoCAD has four workspace configuration

1. 2D Drafting and Annotation 
2. 3D Modeling
3. AutoCAD Classic
4. Initial Setup Workspace       

AutoCAD is shown here with the 2D Drafting & Annotation workspace active

AutoCAD is shown here with the 3D Modeling workspace active   

AutoCAD is shown here with the AutoCAD Classic workspace active.

How can we set the desired workspace in the AutoCAD?

 Click the Workspaces settings icon, located at the bottom right corner of the AutoCAD window.Select 2D  

 Drafting & Annotation.

 

SETTING THE UNITS IN AUTOCAD

       How to set units in AutoCAD?

Before creating the drawing we must set the unit.However, you must decide what units you will use. One drawing unit could represent one millimetre, one centimetre, one metre, kilometre, mile etc.

We can set drawing units in three ways.

• By entering the short key"UN"

• Application menu >Drawing Utilities>UNITS

• Format>UNITS

      
       Drawing Units Dialog Box

 When you enter Units command ,drawing units dialog box will be displayed.You can  set the unit types
  for length, angle, and insertion scale. You can set the precision for both length and angle units and you
  can also set the angle direction. The precision options are displayed in the selected unit format.
  To set your drawing units, select the appropriate unit in the Length and Angle lists and then set the unit's      precision with the Precision lists for length and angle.

            Guidelines for Setting Units

•  While it is possible to set the drawing units at any time, it is recommended that you do this when you   start a new drawing.

•  Regardless of the current unit setting, you can always enter units in decimal format.

•  To input values in a format other than decimal, you must set the appropriate unit type.