Editing Alignments with Grips

As you learned in the first section, alignments are different. They’re smarter and more sophisticated than basic AutoCAD entities. They have more types of grips, and the way they respond to geometric changes is more intelligent. You can leverage this to make quick visual edits to your alignment without ever typing a number or entering a command.

To experiment with using grips to edit alignments, follow these steps:

The Exercise File can be downloaded at the end of the article  

1. Open the drawing named Graphical Editing.dwg located in the Chapter 05 class data folder.
2. Click the Jordan Court alignment to display its grips. Click the upright triangular grip on the second curve, and drag it to a new location. This grip is located at the PI. As you move it, the curve always remains tangent and the radius of the curve remains constant (see Figure 5.4).

   Tips :This exercise goes more smoothly if Osnaps are turned off. If they are turned on, you can press F3 to turn them off.

   Figure 5.4  Moving a PI grip.

3. Click the circular grip at either end of the curve, and move it to a different location. These grips are located at the PC and PT. As you move them, the radius changes and tangency is maintained at both ends of the curve (see Figure 5.5). They can be used to graphically set the exact beginning point or ending point of a curve.

   Figure 5.5  Moving a PC or PT grip.

4. Click the circular grip at the midpoint of the curve, and move it to a different location. This grip is located at a pass-through point, and it forces the curve to pass through that point while maintaining tangency at both ends. This is accomplished by changing the radius of the curve (see Figure 5.6). This grip can be used to make the curve pass through a specific point.

   Figure 5.6  Moving the pass-through-point grip.

5. Click the triangular grip located near the midpoint of the curve, and place it in a new location. This grip controls the radius of the curve while maintaining tangency at both ends of the curve (see Figure 5.7).

   Figure 5.7  Moving the radius grip.

6. Click the square grip at the end of the Jordan Court alignment, and place it in a different location. This type of grip is located at either the beginning or the end of the alignment. As it is moved, the geometry adjacent to it will respond. In the case of this alignment, the curve just before the endpoint changes the locations of its beginning and ending points to remain tangent at both ends (see Figure 5.8).

   Figure 5.8  Moving the start point or endpoint grip.

7. Click the square grip located at the midpoint of the last tangent in the alignment, and move it to a different location. This grip moves the tangent while maintaining its orientation in the drawing. Adjacent geometry responds as needed to meet its geometric rules. In the case of this alignment, the PI to the left of this grip changes location and the curve to the right changes its beginning and ending points to remain tangent (see Figure 5.9).

   Figure 5.9  Moving the tangent midpoint grip.

Editing Alignments

• Editing Alignments with Grips
• Editing Alignments Using the Alignment Layout Tools
• Editing Alignments Numerically

Download Exercise File :

• Editing Alignments - Metric     --- ( 2.44 MB )
• Editing Alignments - Imperial  --- ( 2.18 MB )