Extension Line Origin

Dimensions

Elliot Gindis , in Up and Running with AutoCAD 2016, 2016

Baseline Dimensions

These are continuous stacks of dimensions, as seen in Figure 6.11.

Figure 6.11. Baseline dimensions.

The baseline dimension, as mentioned before, is very similar in principle to the continuous dimension. The goal is to make a neat stack of evenly spaced dimensions that all start at one point (the base in baseline). To begin, erase the previous continuous dimensions (leaving the squares) and once again draw one linear (horizontal) dimension, as seen before in Figure 6.9.

Step 1.

Once you have the squares and one linear dimension, start up the baseline command via any of the preceding methods.

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AutoCAD says: Specify a second extension line origin or [Undo/Select] <Select>:

Step 2.

A new dimension appears. Pick the next point (corner) along the string of rectangles and click on it (always using OSNAP points, no eyeballing).

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AutoCAD says: Dimension text = 4.0

Your value, of course, may be different.

Step 3.

You can continue this until you run out of objects to dimension; at that point, just press Esc. Your result is shown in Figure 6.12.

Figure 6.12. Baseline dimensions result.

Occasionally, just like with the continuous dimension, AutoCAD may not automatically know what the source for the baseline string may have been and ask you to Select base dimension:. Just pick the linear dimension you wish to serve as the "source" and continue with Step 2 as before.

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Dimensions

Elliot J. Gindis , Robert C. Kaebisch , in Up and Running with AutoCAD® 2022, 2022

Linear dimensions

These are any dimensions that are strictly horizontal or vertical (Fig. 6.2). We describe a general approach next, applicable to either the horizontal or vertical dimension, so be sure to practice both. Before you begin, create a generic square or rectangle as seen in Fig. 6.2.

Figure 6.2. Linear (horizontal and vertical) dimensions.

For Ribbon input

Step 1. Press the Ribbon icon (with the sunburst pattern), or type in dim and press Enter.

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AutoCAD says: Select objects or specify first extension line origin or [Angular/Baseline/Continue/Ordinate/aliGn/Distribute/Layer/Undo]:

Step 2. Hover the mouse over any vertical or horizontal line making up the square shape. It becomes highlighted and a horizontal or vertical dimension appears in "preview" mode; shifting around as you move the mouse.

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AutoCAD says: Select line to specify extension lines origin:

Step 3. Click once to select the line to dimension, moving the dimension moving the dimension to its appropriate location, just to the outside of the square.

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AutoCAD says: Specify dimension line location or second line for angle [Mtext/Text/text aNgle/Undo]:

Step 4. Click one last time to fix the dimension in place.

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AutoCAD says: Select extension line origin as baseline or [Continue]:

You are done at this point and can move your mouse to another line that you may wish to dimension. This "one-touch" method of entry was introduced 3   years ago with AutoCAD 2016, somewhat speeding up dimensioning, and it continues with this version of AutoCAD.

For Typing, (Quick Dim)

Step 1. Type in qdim and press Enter.

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AutoCAD says: Associative dimension priority = Endpoint

Select geometry to dimension:

Step 2. Pick any of the lines of your square, with the entire square becoming highlighted.

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AutoCAD informs you: 1 found.

Go ahead and press Enter.

Step 3. Drag the dimension out to its appropriate location, just to the outside of the square. You will not yet see the actual dimension, only the extension lines, as you move the mouse up and down.

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AutoCAD says: Specify dimension line position, or

[Continuous/Staggered/Baseline/Ordinate/Radius/Diameter/datumPoint/Edit/seTtings] <Continuous>:

Step 4. Click one last time to fix the dimension in place. You are done at this point and can repeat the command for another location.

For Typing or Ribbon Input (Linear Dim, "Legacy" Method)

Step 1. Type in dimlinear and press Enter, or press the appropriate Ribbon icon (with a basic horizontal dimension).

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AutoCAD says: Specify first extension line origin or <select object>:

Step 2. With the ENDpoint OSNAP select one of the corners of the square.

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AutoCAD says: Specify second extension line origin:

Step 3. With the ENDpoint OSNAP select any other nearby corner of the square—vertically or horizontally. A dimension appears; go ahead and drag it to its appropriate location.

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AutoCAD says: Specify dimension line location or [Mtext/Text/Angle/Horizontal/ Vertical/Rotated]:

Step 4. Click one last time to fix the dimension in place. The dimension appears and the command line shows the same value you already saw on the screen (e.g., Dimension text   =   2.8422).

To summarize, as you just saw, there are essentially three ways to create virtually any dimension. The first is via the relatively new "one-touch" method. This can be done only via the Ribbon. This method allows you to begin the dimensioning command and "touch" any geometry you want to dimension, with the appropriate dimension appearing automatically. Second is the qdim approach. It has been around for a while and can be accomplished via all four methods of input. It is a bit more cumbersome than Dim, but not by much, giving you the dimensions of some, but not all, geometry selected. It is mostly limited to linear and radius/diameter dimensions. The final version is the much older, but still effective, Linear command. It can also be executed via all four input methods. It requires two points, not a line, to create a linear dimension and takes a bit more time to do.

For users of AutoCAD 2015 and older releases, you can also type in Dim:, press Enter, and type in hor for a horizontal or vert for a vertical dimension, and then proceed to place it point by point following the previous Linear description. This method of command input is not available from AutoCAD 2016 on, but that does not matter much, as the more advanced Dim command can handle point-by-point dimension entry just as easily as the "one-touch" approach if you happen to pick corners instead of lines.

In general, linear dimensions are by far the most common in drawings and are also the basis for the continuous and baseline dimensions, to be covered later. Be sure to run through both the horizontal and vertical linear dimensions, with all methods shown, before settling on one. Next is the aligned dimension, which gives the true distance of a slanted surface. We describe it using the brand-new one-touch approach, but the command matrix shows other options.

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Dimensions

Elliot J. Gindis , Robert C. Kaebisch , in Up and Running with AutoCAD 2019, 2018

For Ribbon or Typing Input (Dim, Primary Method)

Step 1. Press the first Ribbon icon in the command matrix (with the sunburst pattern), or type in dim and press Enter.

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AutoCAD says: Select objects or specify first extension line origin or [Angular/Baseline/Continue/Ordinate/aliGn/Distribute/Layer/Undo]:

Step 2. Hover the mouse over any vertical or horizontal line making up the square shape. It becomes dashed and a horizontal or vertical dimension appears in "preview" mode, shifting around as you move the mouse.

•

AutoCAD says: Select line to specify extension lines origin:

Step 3. Click once and drag the dimension out to its appropriate location, just outside the square.

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AutoCAD says: Specify dimension line location or second line for angle [Mtext/Text/text aNgle/Undo]:

Step 4. Click one last time to fix the dimension in place.

•

AutoCAD says: Select extension line origin as baseline or [Continue]:

You are done at this point and can move your mouse to another line that you may wish to dimension. This "one-touch" method of entry was introduced 3   years ago with AutoCAD 2016, somewhat speeding up dimensioning, and it continues with AutoCAD 2019.

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Dimensions

Elliot Gindis , in Up and Running with AutoCAD 2014, 2014

Aligned Dimension

This is a dimension that measures a slanted line or object (Figure 6.3).

Figure 6.3. Aligned dimensions.

Step 1.

Create a small to medium-size rectangle or square and chop off any corner, or just do this to your existing shape, as seen in Figure 6.3. Then, begin the aligned dimension command via any of the preceding methods.

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AutoCAD says: Specify first extension line origin or<select object>:

Step 2.

Turn on your OSNAPs and, using ENDpoint, select the upper left start of the slanted line.

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AutoCAD says: Specify second extension line origin:

Step 3.

Again, using ENDpoint, select the lower right end of the slanted line. The dimension appears.

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AutoCAD says: Specify dimension line location or [Mtext/Text/Angle]:

Step 4.

Move the mouse up and down and click where you want the dimension to go, usually a short distance from the object. It sets and the value is shown.

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AutoCAD says: Dimension text=2.9255

Your value likely is different, of course.

Again, note an important distinction with keyboard entry. Instead of setting the value in Step 4, AutoCAD throws in one more step, allowing you to alter the dimension on the spot. You can enter a new value or press Enter to accept the natural one. We do not detail the AutoCAD responses with keyboard entry here; the previous linear dimensions should serve as a good example.

The next two dimensions, diameter and radius, are essentially similar, although we cover them separately for clarity. Note the primary differences: the symbol indicating diameter (Ø) and the symbol for radius (R) prior to the value. Although you can set this up, by default there is no line crossing the circle halfway for radius, or all the way across for diameter, so you have to read the values carefully and look for the appropriate symbol to know what you are looking at.

Also, note the location of the values. They are positioned at roughly 10, 2, 4, and 8 o'clock relative to the circle. Do not just put them anywhere; hand-drafting rules still apply in CAD, and designers have typically left them in these positions for clarity, consistency, and style.

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