AUTOCAD Draw toolbar - LINE, POLYLINE, RECT, POLYGON ~ Mechanical Engineering Design Software Tutorials

AutoCAD Basic Draw toolbar Introduction

The Draw commands can be used to create new objects such as lines and circles. Most AutoCAD drawings are composed purely and simply from these basic components. A good understanding of the Draw commands is fundamental to the efficient use of AutoCAD.

The sections below cover the most frequently used Draw commands such as Line, Polyline and Circle as well as the more advanced commands like Multiline and Multiline Style. As a newcomer to

AutoCAD, you may wish to skip the more advanced commands in order to properly master the basics.

You can always return to this tutorial in the future when you are more confident.

Draw toolbar

In common with most AutoCAD commands, the Draw commands can be started in a number of ways. Command names or short-cuts can be entered at the keyboard, commands can be started from the Draw pull-down menu, shown on the right or from the Draw toolbar. The method you use is dependent upon the type of work you are doing and how experienced a user you are. Don't worry too much about this, just use whatever method feels easiest or most convenient at the time. Your drawing technique will improve over time and with experience so don't expect to be working very quickly at first.

1) Lines

Lines are probably the most simple of AutoCAD objects. Using the Line command, a line can be drawn between any two points picked within the drawing area. Lines are usually the first objects you will want to draw when starting a new drawing because

they can be used as "construction lines" upon which the rest of your drawing will be based. Never forget that creating drawings with AutoCAD is not so dissimilar from creating drawings on a drawing board. Many of the basic drawing methods are the same.

Anyone familiar with mathematics will know that lines drawn between points are often called vectors. This terminology is used to describe the type of drawings that AutoCAD creates. AutoCAD drawings are generically referred to as "vector drawings". Vector drawings are extremely useful where precision is the most important criterion because they retain their accuracy irrespective of scale.

Command Sequence

Command: LINE

Specify first point: (pick P1)

Specify next point or [Undo]: (pick P2)

Specify next point or [Undo]: (to

end)

2) The Construction Line command creates a line of infinite length which passes through two picked points. Construction lines are very useful for creating construction frameworks or grids within which to design.

3) The Rectangle Command

The Rectangle command is used to draw a rectangle whose sides are vertical and horizontal. The position and size of the rectangle are defined by picking two diagonal corners. The rectangle isn't really an AutoCAD object at all. It is, in fact, just a closed polyline which is automatically drawn for you.

Command Sequence

Command: RECTANG

Specify first corner point or

[Chamfer/Elevation/Fillet/Thickness/Width]: (pick P1)

Specify other corner point or [Dimensions]: (pick P2)

4) The Polygon Command

The Polygon command can be used to draw any regular polygon from 3 sides up to 1024 sides. This command requires four inputs from the user, the number of sides, a pick point for the centre of the polygon, whether you want the polygon inscribed or circumscribed and then a pick point which determines both the radius of this imaginary circle and the orientation of the polygon.

The polygon command creates a closed polyline in the shape of the required polygon.

This command also allows you to define the polygon by entering the length of a side using the Edge option. You can also control the size of the polygon by entering an exact radius for the circle. Follow the command sequence below to see how this command works.

Autocad Polygon Command

Command Sequence

Command: POLYGON

Enter number of sides <4>: 5

Specify center of polygon or [Edge]: (pick P1 or type E to define by edge length)

Enter an option [Inscribed in circle/Circumscribed about circle] : (to accept the inscribed

default or type C for circumscribed)

Specify radius of circle: (pick P2 or enter exact radius)

In the illustration above, the polygon on the left is inscribed (inside the circle with the polygon vertexes touching it), the one in the

middle is circumscribed (outside the circle with the polyline edges tangential to it) and the one on the right is defined by the

length of an edge.

5) The Spline Command

The Spline command creates a type of spline known as a nonuniform rational B-spline, NURBS for short. A spline is a smooth curve that is fitted along a number of control points. The Fit Tolerance option can be used to control how closely the spline conforms to the control points. A

low tolerance value causes the spline to form close to the control points. A tolerance of 0 (zero) forces the spline to pass through the control points. The illustration on the right shows the effect of different tolerance values on a spline that is defined using the same four control points, P1,

P2, P3 and P4.