Basic Drawing Commands

Basic Drawing Commands

2.1 Creating point

Command: Point

Point objects are useful as nodes or reference geometry for object snaps & relative offsets. You can set the style of the points and their size relative to the screen.

There are different types of points as shown in the figure above. Changing the style of points

1. Makes them more visible and also it is easier to differentiate from grid dots
2. Affects the display of all point objects on the drawing screen.

point mode: Command = pdmode/ddptype

Point size: Command = Pdsize

It's Uses:

1. They are very useful for construction purposes and it helps us to find a coordinate.
2. We can find a point using the NODE object snap. Sometimes, they are used as symbols.

2.2 Creating straight line and construction line

Lines are the most simple and easy objects in AutoCAD drawing. Usually, lines are the first objects you will like to draw when starting a new drawing. It's because they can be used as 'construction lines' and we use it repeatedly in our rest of the drawings. Always remember many of the basic methods of creating drawings with AutoCAD is very similar as creating drawings on a drawing board.

Line command:

It creates single straight line segments between any two points. When you pick the 1st point and move the cursor like cross-hairs to the location of the 2nd point, you will see the rubber band like line that shows you where the line will be drawn after you pick the second point. You can continue to pickthe other points if you want or you can hit ENTER to end this LINE command. Each of the line segments we created are separate objects and they can be erased, copied or moved as per requirement.

1. Choose Draw(from the menu bar), Line.

or

2. Click Line icon from the toolbar.

or

3. Type LINE in the command prompt

Command: LINE (or L)

4. Press ENTER (always after the command is given)
5. Pick any point on the drawing screen with the help of mouse cursor
6. Pick Specify next point or [Close/Undo]:(point)
7. Pick Specify next point or [Close/Undo]:(point)
8. Press ENTER to end line sequence

or

9. Type C to create a closed polygon

To point : C (close) (hit enter)

Construction line:

1. Xline : It helps to create a line of infinite length.

Command: Xline

2.Ray: It helps us to create a line that starts at a point and then continues to infinity. It extends infinitely in only 1 direction from the 1st pick point. The direction of RAY command is determined by the position of the 2nd pick point.

Command: ray

Different ways of drawing X-line

• Horizontal and Vertical:

It creates construction lines that pass through a point you give and are parallel to the X or Y axis of the current UCS (User Coordinate System).

• Angle:

It creates a construction line in one of 2 ways. Either you select a reference line & then give the angle of the construction line from that line, or you create a construction line at a certain angle to the horizontal axis by providing an angle and a point through which the construction line should pass.

• Bisector:

It creates a construction line that bisects an angle you specify. You specify the vertex and the lines that create the angle.

• Offset:

It creates a construction line that is parallel to a baseline you specify. You specify the offset distance, select the baseline, and then indicate on which side of the baseline to locate the construction line.

2.3 Creating circle, arc and ellipse

Besides LINE and POLYLINE, the CIRCLE, ARC and ELLIPSE command are also frequently used commands in AutoCAD drawing. CIRCLE is probably the one that you will use most frequently in upcoming drawings and fortunately it is also very simple to draw.

Circle:

There are no. of ways you can create the circle. The default method is to pick the Center point & then either pick a 2nd point on the circumference of the circle or enter the circle radius'r'.

Command: Circle or C

Different ways of drawing circle:

1. Center, Radius
2. 3-Points
3. 2-Point
4. Center, Diameter
5. Tan, Tan, Radius
6. Tan, Tan, Tan

For instance:

3P (Three Points)

It draws a circle based on3 points on the circumference.

Specify first point on circle: point (1)

Specify second point on circle: point (2)

Specify third point on circle: point (3)

2P (Two Points)

It draws a circle based on 2 endpoint of the diameter.

Specify first endpoint of circle's diameter: point (1)

Specify second endpoint of circle's diameter: point (2)

TTR (Tangent, Tangent, Radius)

It draws a circle with a specified radius tangent to the two objects.

Specify point on obj. for first tangent of circle: Select a circle, arc or line

Specify point on obj. for second tangent of circle: Select a circle, arc or line

Specify radius of circle :

Arc:

Command: Arc

The 'ARC' command allows us to draw an arc of a circle. There are many way to define an arc, where the default process used 3 pick points, a start point, a 2nd point and an end point.

Different ways of drawing arc: Any one of the following ways can be used to draw an arc.

• 3 points
• Start, center, end
• Start, center, angle
• Start, center, length
• Start, end, angle
• Start, end, direction
• Start, end, radius
• Center, start, end

and so on...

For instance:

By specifying 3 points:

You can draw an arc by specifying 3 points.In the following example, the start point of the arc will snap to the endpoint of a line. The 2nd point of the arc will snap to the middle circle in the illustration.

By Specifying Start, Center, End

When you know the start point, center point, and endpoint, you can draw an arc by providing either the start point or the center point at first. The center point is the center of a circle that the arc is part of.

By Specifying Start, Center, Length

If you have a start point & a center point you can snap to; if you know the chord length, use the Start, Center, Length or the Center, Start, Length option in order to draw an arc.

Here, the length of the chord of the arc determines the angle we include.

By Specifying Start, End, Direction/Radius

If you have a start point and an endpoint, use the Start, End, Direction or the Start, End, Radius option to draw an arc.

The example figure on the left shows an arc that is drawn by specifying a start point, endpoint, and radius. You can provide the radius of the arc by entering a length or by moving the pointing device clockwise or counterclockwise and clicking to give a distance.

The example figure on the right shows an arc that is drawn with the pointing device by providing a start point and an endpoint and a direction. Moving the cursor up from the start point and endpoint, it draws the arc concave to the object, as shown in above figure. Moving the cursor down draws the arc convex to the object.

Ellipse:

The ellipse command has the following options:

- Endpoint Axis

- Center

-Arc

Some of the ellipse command options are:

a) The Axis End

This default option requires Picking 3 points as indicated in the command sequence above.

b) The Rotation

If the rotation option is used with the Axis End method, the following syntax is used:

/Rotation: R

Rotation around major axis: Pick

The specified angle is the no. of degrees the shape is rotated from the circular position.

c) The Center

With many practical application, the center point of the ellipse is known, and therefore the center option should be used.

Command: ELLIPSE

Arc/Center/: C

Center of ellipse: Pick or (coordinates)

Axis endpoint: Pick

/Rotation: Pick

(This distance is measured perpendicularity from the established axis))

The rotation option appear and can be invoked after specifying the center first Axis endpoint.

2.4 Creating polygons

We can create rectangles and regular polygons within a few seconds. Creating polygons is a simple way to draw equilateral triangles, rectangles, pentagons, hexagons, octagon and so on. The 'POLYGON' command can be used for drawing any regular polygon from three(3) sides up to 1024 sides. To complete this command it requires 4 inputs from the user. They are: the no. of sides, a pick point for Center of the polygon, the polygon inscribed or circumscribed and a pick point which determines the radius of the imaginary circle and the orientation of the polygon both.

You can also create the polygon by entering the length of a side by using the Edge option and you can control the size of polygon by entering an exact 'r' for the circle.

We can create polygons by any one of the following ways:

To draw a circumscribed polygon

1. Click Draw menu > polygon.
2. In the command line, enter the no. of sides.
3. Specify the center of the polygon (1).
4. Enter 'c' to specify a polygon circumscribed about a circle.
5. Enter the radius length (2).

To draw an inscribed polygon

1. Click Draw menu > polygon.
2. In the command line, enter the no. of sides.
3. Specify the center of the polygon.
4. Enter 'i' to specify a polygon inscribed within a circle of specified points.
5. Enter the radius length.

To draw a polygon by specifying 1 edge

1. Click on Draw menu > polygon.
2. In the command line, enter the no. of sides.
3. Enter 'e' (i.e. Edge)
4. Specify the start point for 1 polygon segment.
5. Specify the endpoint of the polygon segment.

Spline:

Splines are defined either with control vertices or with fit points. By default, the fit points coincide with the spline, while the control vertices define acontrol frame. The control frames provide a convenient method to shape the spline. Each method has its advantages.

The SPLINE command creates a particular type of spline known as a non uniform rational B-spline curve. A NURBS curve produces a smooth curve between control points. You create splines by specifying points. You can close the spline so that the start and endpoints are coincident and tangent.

You can use any of the following methods for creating splines:

1. Choose Draw (from menu bar), spline

or

2. Click on the 'SPLINE' icon.

or

3. Type SPLINE (in the command line)

Command: SPLINE

then,

4. Select any starting point for the spline

object/:(pick point)

5. Select points until you complete the structure of the spline

enter point:(pick points)

6. Press 'ENTER' or 'CLOSE' to complete the spline
7. Pick starting tangent point for the same spline

enter the start tangent:(pick point)

8. Pick ending tangent point for spline

enter the end tangent:(pick point)