19-06-2012, 12:15 PM
Computer Aided Design
Computer aided design (CAD) can be defined as any design activity that involves the effective use of computers to create, modify or document an engineering design.
Reasons for using CAD:
(a) To increase the productivity of the designer.
(b) To improve the quality of design.
© To improve design documentation.
(d) To create manufacturing database.
CAD involves the following components:
(a) Drafting (2D)
(b) Modeling (3D)
A typical CAD system essentially consists of following components:
(a) Workstation (commonly known as PC)
CPU
Input devices
Graphics terminal
(b) Secondary storage device
© Plotting device
COMMANDS OF 2D
SAVE
This command allows us to save our drawing in AutoCAD environment.
OPEN
This command use to open our created AutoCAD file.
LIMITS
This command allows us to change the upper and lower limits of the drawing area. By default the size of screen is 12x9 units. Limits are always to be specified in two dimensions i.e. we are just to specify the X and Y coordinates for the lower left corner and upper right corner. We cannot put limits for the Z direction as Z direction is kept limitless.
ZOOM
This is the second command i.e. this command should follow the LIMITS command. It magnifies the drawing on display screen or shrinks it. Use “ALL” option to apply the limits selected. From zoom command we can also switch to PAN or 3ORBIT, this can be dome by right clicking the mouse button and choosing the mode we require.
CIRCLE
We use this command to draw circle using various different methods. We can create a circle by beginning with the center point or one of three points on the circumference (3p OR 2p), or we can select objects to which the circle is tangent.
OSNAP
It helps in easy selection of various parts of the figure like center, endpoint etc. Whichever option we’ll select will get highlighted when we’ll move cursor on it or close to it. Osnap options look like as shown in previous figure.
DRAW ARCS BY SPECIFYING START, CENTER AND END: When we know the start point, center point and end point, we can draw an arc by specifying either the start point or the center point first. The center point is the center of a circle that the arc is part of.
DRAW ARCS BY SPECIFYING START,CENTER AND ANGLE: When we have a start point and s center point we can snap to and we know the included angle, use the start, Center, Angle or the Center, Start, Angle option.
DRAW ARCS BY SPECIFYING START, CENTER AND LENGTH: When we have a start point and a center point we can snap to; when we know the chord length, use the Start, Center, Length or the Center, Start, Length option. The length of the chord of the arc determines the included angle.
Computer aided design (CAD) can be defined as any design activity that involves the effective use of computers to create, modify or document an engineering design.
Reasons for using CAD:
(a) To increase the productivity of the designer.
(b) To improve the quality of design.
© To improve design documentation.
(d) To create manufacturing database.
CAD involves the following components:
(a) Drafting (2D)
(b) Modeling (3D)
A typical CAD system essentially consists of following components:
(a) Workstation (commonly known as PC)
CPU
Input devices
Graphics terminal
(b) Secondary storage device
© Plotting device
COMMANDS OF 2D
SAVE
This command allows us to save our drawing in AutoCAD environment.
OPEN
This command use to open our created AutoCAD file.
LIMITS
This command allows us to change the upper and lower limits of the drawing area. By default the size of screen is 12x9 units. Limits are always to be specified in two dimensions i.e. we are just to specify the X and Y coordinates for the lower left corner and upper right corner. We cannot put limits for the Z direction as Z direction is kept limitless.
ZOOM
This is the second command i.e. this command should follow the LIMITS command. It magnifies the drawing on display screen or shrinks it. Use “ALL” option to apply the limits selected. From zoom command we can also switch to PAN or 3ORBIT, this can be dome by right clicking the mouse button and choosing the mode we require.
CIRCLE
We use this command to draw circle using various different methods. We can create a circle by beginning with the center point or one of three points on the circumference (3p OR 2p), or we can select objects to which the circle is tangent.
OSNAP
It helps in easy selection of various parts of the figure like center, endpoint etc. Whichever option we’ll select will get highlighted when we’ll move cursor on it or close to it. Osnap options look like as shown in previous figure.
DRAW ARCS BY SPECIFYING START, CENTER AND END: When we know the start point, center point and end point, we can draw an arc by specifying either the start point or the center point first. The center point is the center of a circle that the arc is part of.
DRAW ARCS BY SPECIFYING START,CENTER AND ANGLE: When we have a start point and s center point we can snap to and we know the included angle, use the start, Center, Angle or the Center, Start, Angle option.
DRAW ARCS BY SPECIFYING START, CENTER AND LENGTH: When we have a start point and a center point we can snap to; when we know the chord length, use the Start, Center, Length or the Center, Start, Length option. The length of the chord of the arc determines the included angle.