AutoCAD Tutorials (categ.)

2.2.1 - Parts of a Dimension

With dimensions in AutoCAD, you can add measurements to your drawing, for conveying informationto the audience that will be looking at your drawing.
You can create several types of dimensions and control their appearance by setting up dimension styles or by editing individual dimensions.

Dimensions have several dinstict elements, such as:

Dimension text : Is the dimension value, usually shown inside or above the dimension.
Dimension line : Is the line that represent the distance being dimensioned. It indicates the direction and extend of a dimension. For angular dimensions the dimension line is an arc.
Arrowheads : Are symbols displayed at each end of the dimension line, in different sizes and shapes, for arrowheads or tick marks.
Extension lines : Are the lines that extends from the object being dimensioned, to the dimension line.
Dimension line extension : Is a part of the dimension line that extends beyond the extension line.
Extension beyond dimension line : Specifies a distance to extend the dimension line past the extension line.
Offset from origin : Sets the distance to offset the extension lines from the points on the drawing that define the dimension.
Offset from dimension line : Sets the distance to offset the dimension value (text) from the dimension line.

Fig. 3.1.1.1 - The Components of a Dimension

Fig. 3.1.1.1 - The Components of a Dimension

You can control each of these components, by edtiting or creating dimension styles.


2.2.2 - Types of Dimensions

The basic types of dimensions are:

  • Linear (horizontal and vertical)
  • Aligned
  • Radial (radius, diameter, arc)
  • Angular
  • Continuous
  • Baseline
  • Leader

Fig.3.1.1.2 - Dimension types

Fig.3.1.1.2 - Dimension types

2.2.2.1 - Linear Dimensions

In AutoCAD enviroment:

Draw an object like the one you see in Fig.2.2.2.1, without the dimensions and their description. (You will use for this the commands Polyline or Line, Circle and Elipse), or if you wish, you can also download this dwg file by ckliking here (icon), and open it with autocad.

  • Create a new Layer, set as name: A-Notes, as color: Red,  and set it is as Current.
  • Click Home tab ► Annotation panel ► select Leader icon acad icon dimLinear 8630
  • Command prompt says: Specify first extension line origin or <select object>: Turn on your OSNAPs (icon), and using ENDpoint (icon), select the uper left corner (a) of the polygon (Fig.2.1.2.2).
  • Command prompt says: Specify second extension line origin: Again using ENDpoint (icon), select the uper right corner (b) of the polygon.
  • The (horizontal) dimension (ab) appears, attached to the movement of your mouse.
  • Command prompt says: Specify dimension line location or[Mtext Text Angle Horizontal Vertical]: Move the mouse up and down and click where you want the dimension to be placed.
  • With the same proccess, create the linear dimensions for the left vertical sides (ab), (de), and the bottom horizontal side (bc) of the polygon as shown in Fig.2.2.2.2.

Fig.3.1.2.1 - Create Linear Dimension

Fig.3.1.2.1 - Create Linear Dimension

2.2.2.2 - Aligned Dimensions

Next you will create the algned dimension (cd).

  • Click Home tab ► Annotation panel ► select Linear icon acad icon dimAligned 7830
  • Command prompt says: Specify first extension line origin or <select object>: Turn on your OSNAPs (icon), and using ENDpoint (icon), select the down right point (c) of the polygon (Fig.2.1.1.2).
  • Command prompt says: Specify second extension line origin: Again using ENDpoint (icon), select the uper right corner (d) of the polygon.
  • The aligned dimension (cd) appears, attached to the movement of your mouse.
  • Command prompt says: Specify dimension line location or[Mtext Text Angle Horizontal Vertical]: Move the mouse up and down and click where you want the dimension to be placed.
  • You created the aligned dimension for the inclined side (cd), of the polygon as shown in Fig.2.2.1.2.

 

2.2.2.3 - Radial Dimensions

Raial dimensions measure the radius and diameter of arcs and circles.

Create a diameter dimension

  • Click Home tab ► Annotation panel ► select Diameter icon acad icon dimDiameter 9040
  • Command prompt says: DIMDIAMETER Select arc or circle: Select the circle, as shown in Fig.2.2.1.0.
  • Command prompt says: Specify dimensionline location or[Mtext Text Angle] : Specify with your mouse the leader line position, as shown in Fig.2.2.1.3.

The value and the dimension of the diameter are shown like this: Ø0.500.

Create a radius dimension

  • Click Home tab ► Annotation panel ► select Diameter icon acad icon dimDiameter 9040
  • Command prompt says: DIMRADIUS Select arc or circle: Select the circle, as shown in Fig.2.2.1.3.
  • Command prompt says: Specify dimensionline location or[Mtext Text Angle] : Specify with your mouse the leader line position, at the uper right side of the circle (outside), as shown in Fig.2.2.1.0.

The value and the dimension of the radius are shown like this: R0.250.

Fig.3.1.3.1 - Create Radial Dimensions

Fig.3.1.3.1 - Create Radial Dimensions

2.2.2.4 - Angular dimension

Create the angular dimension of an arc of the circle:

  • Click Home tab ► Annotation panel ► select Angular icon acad icon dimAngular 9040
  • Command prompt says: DIMANGULAR Select arc, circle, line, or , <Specify vertex>: Select a point on the circle.
  • Command prompt says: DIMANGULAR Specify second angle endpoint: Specify a second point on the circle.
  • Command prompt says: DIMANGULAR Specify dimension arc Line location: Specify with your mouse the arc line position,at the uper left side outside of the circle, as shown in Fig.2.2.1.4.
  • Command prompt says: Specify dimensionline location or[Mtext Text Angle] : Specify with your mouse the leader line position,at the uper right side of the circle (outside), as shown in Fig.2.2.1.4.

The value and the dimension of the radius are shown like this: R0.250 .

 

Create the angular dimension between the two lines (bc) and (ce):

  • Click Home tab ► Annotation panel ► select Angular icon acad icon dimAngular 9040
  • Command prompt says: DIMANGULAR Select arc, circle, line, or , <Specify vertex>: Select line (bc), as shown in Fig.2.2.1.4.
  • Command prompt says: DIMANGULAR Select second line or : Select line (ce).
  • Command prompt says: DIMANGULAR Specify dimension arc Line location [Mtext, Text, Angle, Quadrant]: Specify with your mouse the best position for the angular dimension, and click when you find a position you like, as shown in Fig.2.2.1.4.

The value and the angular dimension of the two lines are as shown in Fig.2.2.1.4.

Fig.3.1.3.2 - Create Angular Dimensions

Fig.3.1.3.2 - Create Angular Dimensions


 

2.2.2.5 - Baseline dimensions

Baseline dimensions are multiple dimensions measured from the same baseline. You have to create a linear dimension before you create baseline dimensions.

By default the origin of the last linear dimension created is used as the first extension line for the new baseline dimension. You are prompted for the second dimension line.

  • Click Annotate tab ► Dimensions panel ► select Linear icon acad icon dimLinear 8630, and draw the linear dimension (bf) as shown in Fig..2.2.1.5.
  • Click Annotate tab ► Dimensions panel ► select Baseline icon acad icon dimBaseline 9040
  • Command prompt says: DIMBASELINE Specify a second extension line origin or [Undo, Select]<Select>: Select point (g), the dimension (bg) will be created starting from point (a) that is the first point of the existing linear dimension ((af), continue selecting  point (c), poit (d), and press Esc.
  • The result is as shown in Fig.2.2.1.5.

The values and the baseline dimensions are as shown in Fig.2.2.1.5.

Fig.3.1.2.2 - Create Baseline Dimensions

Fig.3.1.2.2 - Create Baseline Dimensions

Adjust the line spacing between dimensions

  • Click Annotate tab ► Dimensions panel ► select Ajust Spase tool icon acad icon dimAjustSpace 28
  • Command prompt says: DIMSPACE Select base dimension : Select dimension (bf) as shown in Fig.2.2.1.5.
  •   Command prompt says: DIMSPACE Select dimensions to space : Select the next dimension (bg), continue selecting the other two dimensions (bc) and (bd) , and press Enter.
  •   Command prompt says: DIMSPACE Enter value or [Auto] <Auto> : Enter 0.15 to define the value of spacing between the dimensions , and press Enter.

Notice on your drawing that the line spacing of the cimensions has changed.


 

2.2.2.6 - Continuous dimensions

Cuntinued dimensions are multiple dimensions placed end to end.

You have to create a linear dimension before you create baseline dimensions.

By default the origin of the last linear dimension created is used as the first extension line for the new baseline dimension. You are prompted for the second dimension line.

  • Click Annotate tab ► Dimensions panel ► select Continue icon acad icon dimContinue 9040
  • Command prompt says: DIMCONTINUE Select continued dimension: Select the linear dimension (bg) you just created, the program uses the origin point (f) of the existing dimension (bf), as the first extension line starting from point (f). Select  selecting  point (c), poit (d), and press Esc.
  • Command prompt says: DIMCONTINUE Specify a second extension line origin or [Undo, Select]<Select>: Select point (g), the dimension (fg) will be created starting from point (f) that is the second point of the existing linear dimension (af), continue selecting  point (c), poit (d), and press Esc.
  • The result is as shown in Fig.2.2.1.6.

Fig.3.1.2.3 - Create Continuous Dimensions

Fig.3.1.2.3 - Create Continuous Dimensions


 

2.2.2.7 - Leader - Multileader

A leader object is a line with an arrowhead at one end and a multiline text object or block at the other.

The landing and leader line are associated with the multiline text object or block, so when the landing is relocated, the content and leader line move along with it.

Create a leader

  • Click Home tab ► Annotation panel ► select Leader icon acad icon leader 8028
  • Command prompt says: MLEADER Specify arrowhead location or [Leader Landing first, Content first, Options] <Options> : Select a point on the circle , as shown in Fig.2.2.2.0,
  • Command prompt says: MLEADER Specify leader landing : Select a point on the circle , as shown in Fig.2.2.2.0,
  • The result is as shown in Fig.2.2.1.6.

Fig.3.1.4.1 - Leader components - Create Leaders

Fig.3.1.4.1 - Leader components - Create Leaders

A Leader typically consists of the following components (Fig.2.2.2.0):

  • Arrowhead     : Its start point is specified with mouse
  • Leader line    : It is specified with mouse
  • Landing line  : It is defined at leader style
  • Landing gap  : It is defined at leader style
  • Text or block  : It is inserted in the drawing

You can create a leader from any point of your drawing and modify its appearance as you draw.

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