Many drawings have symmetrical elements. Often, especially in mechanical drawings, you can create one half or one quarter of a model and complete it simply by mirroring what you have drawn.

The command prompts you for the first and second points of the mirror line. This is an imaginary line across which the command creates the mirrored object. The length of the line is irrelevant — only its start point and direction are important.

The command then asks if you want to erase the source objects. The source objects are the objects you have selected to mirror. If you want to keep them, type n

STEPS: Mirroring Objects

The ARRAY command creates a rectangular or polar (circular) pattern by copying the object(s) you select as many times as you specify. The ARRAY command is a powerful drawing tool. It can quickly create large numbers of objects, thus saving a huge amount of time and effort.

Rectangular arrays

A rectangular array creates a grid of rows and columns of one or more objects. Figure 10.3 shows an example of a rectangular array. To create a rectangular array, follow these steps:

Figure 10.3. The garage door was drawn with one panel, as shown on the left side. A rectangular array created the rest of the door panels, as shown on the right.

1. 
   

   Figure 10.4. The Array dialog box.

2. Click Rectangular Array at the upper-left corner of the dialog box (if it is not already selected).

3. If you've already selected one or more objects, the dialog box indicates the number of selected objects. If you haven't selected any object, click Select Objects to return to your drawing and select objects. Press Enter to end object selection and return to the dialog box.

4. In the Rows and Columns text boxes, type the total number of rows and columns that you want.

5. Type the distance you want between the rows in the Row Offset text box, and type the distance you want between the columns in the Column Offset text box. If you want to specify the offsets by picking points on your screen, click the Pick button next to the Row Offset or Column Offset text box, or use the longer Pick button spanning both text boxes to pick diagonal points and specify both offsets at once.

6. If you want to change the angle of the array, type an angle in the Angle of Array text box. The preview panel displays the results of this value. To specify the angle by picking, click the Pick Angle of Array button.

7. To preview the array, click Preview. Click anywhere (pick) or press Esc to return to the Array dialog box if you want to make changes; otherwise, right-click to accept the array and end the command. If you change the snap angle or the UCS (as explained in Chapter 8), AutoCAD and AutoCAD LT create the rectangular array at the angle of the snap or UCS.

Polar (circular) arrays

A polar array creates copies of one or more objects arrayed in a circle around a center point. An example of a polar array is shown in Figure 10.5.

Figure 10.5. The pulley was drawn with one spoke, as shown on the left. A polar array created the additional spokes.

To create a polar array, follow these steps:

1. 

2. Click Polar Array at the top of the dialog box (if it is not already selected).

3. If you've already selected one or more objects, the dialog box indicates the number of selected objects. If you haven't selected any objects, click Select Objects to return to your drawing and select objects. Press Enter to end object selection and return to the dialog box.

4. Specify the center point by typing X and Y coordinates, or click the Pick Center Point button. If you selected an object first, check that the center point displayed is what you want.

5. Select the two items that you want to specify from the Method drop-down list. You can choose any two from the three choices:

   • Total Number of Items. Sets the total number of items in the resulting array, including the one that you are arraying.

   • Angle to Fill. Sets the number of degrees that the polar array covers. For example, to array around half of a circle, specify 180°.

   • Angle Between Items. Specifies the number of degrees between each item in the polar array.

6. Complete the values of the two items that you specified. You can click the buttons to pick the angle to fill or the angle between items on the screen.

7. Check the Rotate Items as Copied check box to rotate the objects that you are arraying. Uncheck the box to leave them unrotated.

8. Click Preview to preview the array. Click anywhere (pick) or press Esc to return to the Array dialog box if you want to make changes; otherwise, right-click to accept the array and end the command.

You can specify which point on the last object selected that AutoCAD or AutoCAD LT uses to array the objects. The command makes a calculation of the distance from the center point of the array to a base point on the last object selected. Otherwise, the command uses a default point based on the type of object selected. Table 10.1 lists the default base points. If you are arraying more than one object, you may not obtain the result you want without specifying the base point. Even for one object, you may want to change the base point that is used.

To specify the base point, click the More button at the bottom of the dialog box. The dialog box opens up to display the Object Base Point section. Uncheck Set to Object's Default. You can then either type in coordinates or, more likely, click the Pick Base Point button and use an object snap to pick the desired point on an object. The preview box adjusts according to your choice, but because the preview only shows rectangles in the place of your object, the display may not be very helpful. You can click the Preview button to preview the result in your drawing.

Note

You can use the Express Tools COPYM command to enhance your copying options. Type copym

Table 10.1. Object Base Points for Arrays

Type of Object	Default Base Point
Arc, circle, or ellipse	Center point
Polygon or rectangle	First corner
Line, polyline (2D or 3D), ray, spline, or donut	Starting point
Text (single-line or paragraph), block	Insertion point
Construction line (xline)	Midpoint
Region	Grip point

Note

The drawing used in the following exercise on arraying objects, ab10-a.dwg, is in the Drawings folder on the DVD.

STEPS: Arraying Objects

1. Open ab10-a.dwg from the DVD.

2. Save the file as ab10-02.dwg in your AutoCAD Bible folder. It looks like Figure 10.6. Object Snap mode should be on. Set Center and Intersection running object snaps.

   

   Figure 10.6. A partially completed mounting bracket.

3. 

4. Click the Select Objects button of the Array dialog box. In the drawing, pick the horizontal centerline

   

5. Make sure that Rectangular Array is selected at the top of the dialog box.

6. In the Rows text box, type 4. In the Columns text box, type 1.

7. In the Row Offset text box, type 1. (You don't need to specify the column offset because you are creating only one column.)

8. Click Preview. You should see a total of four horizontal lines, as shown in Figure 10.7. Right-click to accept the array. (If you don't see the four lines, click anywhere in the drawing area and recheck the settings in the Array dialog box.)

9. To add the holes to the pattern, again start the ARRAY command.

10. Click the Select Objects button in the Array dialog box. In the drawing, pick circle

    

11. Back in the Array dialog box, type 4 in the Rows text box and type 2 in the Columns text box.

12. Click the Pick Both Offsets button. In the drawing, pick the center of circle

    

13. Click Preview to preview the array. If the circles look like Figure 10.7, right-click. Otherwise, click in the drawing area or press Esc and check your settings. After you're done, the command arrays the holes to fit the centerlines.

14. To create a six-hole bolt circle, pick hole

    

15. Start the ARRAY command again.

16. In the Array dialog box, choose Polar Array.

17. Next to the Center Point text boxes, click the Pick Center Point button. In the drawing, pick the center of the large circle at

    

18. Make sure that the Method reads ″Total number of items & Angle to fill.″ In the Total Number of Items text box, type 6. In the Angle to Fill text box, type 360.

19. Click Preview to see the array. It should look like Figure 10.7. If it does, right-click. Otherwise, click in the drawing area or press Esc and recheck the settings in the Array dialog box. AutoCAD or AutoCAD LT completes the mounting bracket.

20. Save your drawing. It should look like Figure 10.7.

    

    Figure 10.7. The completed mounting bracket.

The OFFSET command creates lines or curves parallel to one existing object. The beauty of this command is apparent when you start to create complex objects, such as polylines, which are covered in Chapter 16. Polygons and rectangles are polylines, which means that all the line segments are one object. For example, using OFFSET, you can create concentric polygons in one step. Figure 10.8 shows two concentric polygons. The outside polygon was created with the POLYGON command, and the inside polygon was created by using OFFSET.

Figure 10.8. Use OFFSET to create concentric polygons.

The command responds with the following list of settings and prompt:

Current settings: Erase source=No  Layer=Source  OFFSETGAPTYPE=0
Specify offset distance or [Through/Erase/Layer] <Through>:

The settings show how the OFFSET command's options will function. Set the Erase option to Yes to erase the selected object and leave only the offset. Use the Layer option to specify if you want the new object to be on the same layer as the source object or on the current layer.

The OFFSET command offers two ways to specify the offset:

Use the Undo option if you don't like the result of the offset. After you offset an object, the prompt repeats so that you can offset additional objects. Press Enter to end the command.

STEPS: Using the OFFSET Command

The ALIGN and 3DALIGN commands let you move and rotate an object or objects in one procedure. They are useful in both 2D and 3D environments. By specifying where selected points on an object move, you can align the object with other objects in your drawing, as shown in Figure 10.11. You can align in two ways:

Aligning requires several steps. Even so, it can save you time when you need to move and rotate at the same time, especially if you don't know the rotation angle that you need.

Figure 10.11. Aligning a door with a wall.

Using the ALIGN command

1. The prompt asks for the first source point. Specify a point, usually an object snap on the object that you want to move.

2. The prompt asks for the first destination point. Specify the point where you want the first source point to end up.

3. The prompt asks for the second source point. If you press Enter, AutoCAD simply moves the selected objects. To continue to align, specify another point, usually another object snap on the object that you want to move.

4. The prompt asks for the second destination point. Specify the point where you want the second source point to end up.

5. The prompt asks for the third source point. You use this for 3D alignment, to specify how you want to rotate the object in the third dimension. For 2D alignment, press Enter to continue the command.

6. The prompt displays the Scale objects based on alignment points? [Yes/No] <N>: prompt. If the distances between the source and destination points are not the same, type y if you want to scale the original object so that the source and destination points match exactly.

Using the 3DALIGN command

Then follow these steps:

1. The message, Specify source plane and orientation, explains that you now need to specify the source points, which define the plane and orientation of the source object. The first prompt asks for the base point. Specify a point, usually an object snap on the object that you want to move. This point will match the first destination point. You can use the Copy option to make a copy of the object rather than move it. If you use the Continue option here, you only move the object.

2. The prompt asks for the second point. Specify another point on the source object. This point will match the second destination point. Use the Continue option to start specifying destination points.

3. The prompt asks for the third point. In 3D models, you need the third point to specify the plane.

4. The message, Specify destination plane and orientation, explains that you now need to specify the destination points for the base points you just specified. The prompt asks for the first destination point. Specify the point where you want the first base point to end up. As soon as you do this, the object moves to match the first base and destination points so that you can see how the object will look.

5. The prompt asks for the second destination point. The second base point will match this point. If you press Enter at this point, the command aligns the object with the X axis of the current UCS.

6. The prompt asks for the third destination point. You use this for 3D alignment, to specify how you want to rotate the object in the third dimension. For 2D alignment, you can place the cursor on either side of the aligning line you specified, to mirror the object in either direction. When you see the direction that you want, press Enter to end the command and align the object.

The following exercise uses the ALIGN command to align objects.

Note

The drawing used in the following exercise on aligning objects in two dimensions, ab10-c.dwg, is in the Drawings folder on the DVD.

STEPS: Aligning Objects in Two Dimensions

1. Open ab10-c.dwg from the DVD.

2. Save the file as ab10-04.dwg in your AutoCAD Bible folder. It looks like Figure 10.12. Set a running object snap for Endpoint.

   

   Figure 10.12. A base assembly for a commercial washing machine.

3. 

   Select objects: Select the horizontal angle by using a window, picking near 
    and then 
   . Press Enter to end object selection. This angle needs to be aligned with the long, diagonal support angle.
   Specify first source point: Pick the endpoint at 
    in Figure 10.12.
   Specify first destination point: Pick the endpoint at 
   .
   Specify second source point: 
   
   Pick the endpoint at 
   .
   Specify second destination point: Pick the endpoint at 
   .
   Specify third source point or <continue>: 
   
   Scale objects based on alignment points? [Yes/No] <N>: 
    to accept the default No answer.

4. Save your drawing. It should look like Figure 10.13.

Figure 10.13. The washing machine base.

As you edit a drawing, you may find that lines or arcs that once perfectly met other objects now hang over. To trim an object, you must first specify the cutting edge, which defines the point at which to cut the object you want to trim. You define the cutting edge by selecting an object. You can select several cutting edges and several objects to trim at one time, as shown in Figure 10.14. When you select an object to trim, you must pick the object on the side that you want trimmed (not on the side that you want to remain). A common use for the TRIM command is to create intersections of walls in architectural floor plans.

The object you want to trim does not have to actually intersect the cutting edge. You can trim an object to a cutting edge that would intersect the object if extended. This is called trimming to an implied intersection, an example of which is shown in Figure 10.15.

Figure 10.14. Trimming two objects by using two cutting edges.

Figure 10.15. Trimming two arcs to an implied intersection.

You can trim arcs, circles, ellipses, elliptical arcs, lines, polylines, xlines, rays, and splines. You can use polylines, arcs, circles, ellipses, elliptical arcs, lines, rays, regions, splines, text, or xlines as cutting edges. An object can be used as both a cutting edge and an object to be trimmed in the same trimming process. You can also trim to objects within blocks. (Chapter 18 covers blocks.)

You can trim to an actual or an implied intersection (an intersection that would exist if objects were extended):

Use the Undo option if the results of the trim are not what you want. You can then continue to select objects to trim. The eRase option lets you erase an object instead of trimming it, without leaving the TRIM command.

STEPS: Trimming Objects

Figure 10.16. A schematic of an air compressor.

Figure 10.17. The completed clamp in two views.

The EXTEND command has similar prompts to the TRIM command, but instead of trimming objects to a cutting edge, it extends them to a boundary edge (see Figure 10.18). As with TRIM, when you select an object to extend, you must pick the object on the side that you want extended (not on the side that you want left as is).

The object you want to extend does not have to actually intersect the boundary edge after its extension. You can extend an object to a boundary edge that would intersect the extended object if it were longer. This is called extending to an implied intersection, an example of which is shown in Figure 10.19.

Figure 10.18. Extending two lines by using an arc as the boundary edge.

Figure 10.19. Extending a line to an implied intersection.

You can extend arcs, elliptical arcs, lines, open polylines, and rays. You can use polylines, arcs, circles, ellipses, elliptical arcs, lines, rays, regions, splines, text, or xlines as boundary edges. An object can be used as both a boundary edge and an object to be extended in the same extending process.

Use the Undo option if the results of the extension are not what you want. You can then continue to select objects to extend. You can use the Fence object selection method to select objects to extend the side of the object that the fence line crosses.

STEPS: Extending Objects

Figure 10.20. An electrical schematic.

Figure 10.21. The completed electrical schematic.

The LENGTHEN command both lengthens and shortens. It works on open objects, such as lines, arcs, and polylines, and also increases or decreases the included angle of arcs. AutoCAD and AutoCAD LT offer several ways of defining the new length or included angle. Use LENGTHEN if you want to lengthen or shorten an object when there is no available intersecting edge or boundary to use with TRIM or EXTEND.

In the LENGTHEN command, the length of an arc is measured along its circumference. Don't confuse this with the Length of Chord option of the ARC command, which refers to the length of a line stretched from one endpoint of the arc to the other endpoint.

After you've used an option to specify the length you want, you see the Select an object to change or [Undo]: prompt. Here you select the object you want to change. Be sure to pick the endpoint of the object for which you want to make the change.

The same prompt continues so that you can pick other objects by using the same length specifications. Choose Undo to undo the last change. Press Enter to end the command.

STEPS: Lengthening and Shortening Objects

The STRETCH command is generally used to stretch groups of objects. For example, you can use this command to enlarge a room in a floor plan. You can also shrink objects. You can change not only the length of the objects but the angle as well. You use a crossing window to choose the objects to be stretched. All objects that cross the boundaries of the crossing window are stretched. All objects that lie entirely within the crossing window are merely moved. Successful stretching involves precise placement of the crossing window. Figure 10.24 shows the process of stretching a garage. Note that the walls that cross the boundaries of the crossing window are stretched. However, the dormer that is entirely within the crossing window is just moved. This maintains the integrity of the model.

You cannot stretch circles, text, or blocks. You can stretch arcs, although the results may not be what you expect.

The real power of the STRETCH command is in stretching a number of objects at once. However, you can also stretch one line. The results are similar to using the CHANGE command to change the endpoint of a line or to editing with grips (discussed later in this chapter).

Figure 10.24. Stretching a garage.

The STRETCH command remembers the most recent displacement throughout a session. To stretch an object by the same displacement that you most recently used, press Enter at the Specify base point or [Displacement] <Displacement>: prompt. At the Specify displacement <2.0000, 3.0000, 0.0000>: prompt, you see in angled brackets the last displacement that you used. Press Enter to stretch the object using this displacement.

When you've finished selecting objects, you see the Specify base point or Displacement <Displacement>: prompt. This step is just like moving objects, and you can respond in two ways:

When specifying a displacement by typing at the keyboard, you can use both positive and negative distances. For example, 6′<180 is the same as −6′<0. Both would stretch the objects 6 feet to the left.

STEPS: Stretching Objects

Figure 10.25. A plan view of a garage.

Figure 10.26. The longer garage.

Drawing a long line and then breaking it into two or more shorter lines is often much easier than drawing two separate lines. A common use for BREAK is to break a wall at a door or a window in an architectural floor plan. You specify two points on the object, and the command erases whatever is between those two points. Typically, you use object snaps to specify the points. Sometimes, you can use TRIM to break an object, but if you have no convenient cutting edge, you may find BREAK more efficient.

Tip

You can use BREAK to shorten an object. Pick one point on the object where you want the new endpoint to be. Pick the other point past its current endpoint to cut off the object at the point you picked on the object.

The opposite of breaking objects is joining them. The JOIN command lets you join lines, polylines, arcs, elliptical arcs, and splines. The objects must be along the same linear, circular, or elliptical path. The objects can overlap, have a gap between them, or touch end to end.

Select source object: Select the first object that you want to join.
Select lines to join to source: Select the second object. (AutoCAD knows which type of object you've selected for the first prompt and inserts it into the second prompt.) You can continue to select other objects. Press Enter to end selection.

AutoCAD joins the objects.

A nice touch is the ability to close arcs (to circles) and elliptical arcs (to ellipses). If your first object is either type of arc, you see the Select arcs to join to source or [cLose]: prompt. Use the cLose option to close the arc.

Note

STEPS: Breaking and Joining Objects

Note

The Express Tools contain a command, BREAKLINE, to create a break symbol. Choose Express Tools

The CHAMFER command creates corners from two nonparallel lines. You can also chamfer xlines, rays, and polylines. You can simply extend the lines to meet at an intersection (a square corner), or create a beveled edge. If you create a beveled edge, you define the edge by either two distances or one distance and an angle relative to the first line that you're chamfering. Figure 10.29 shows the elements of a chamfered corner.

Figure 10.29. A chamfered corner.

Chamfering is a two-step process. First you define how you want to chamfer the corner, specifying either two distances from the corner or a distance and an angle. Then you select the two lines that you want to chamfer.

Now that you have specified the settings that you want, you're ready to chamfer. Your distances or distance and angle are displayed as you just specified them. The command repeats the Select first line or [Undo/Polyline/Distance/Angle/Trim/mEthod/Multiple]: prompt. Select the first line. If you aren't creating a chamfer with equal distances, the order in which you select the lines is important. The command trims the first line selected by the first distance, and the second line selected based on either the second distance or the angle. At the Select second line or shift-select to apply corner: prompt, select the second line to chamfer the lines.

If the lines already intersect, the command trims them to create a corner. The pick points on intersecting lines should be on the part of the lines that you want to keep, not on the part of the lines that you want to trim off.

By default, CHAMFER trims the original lines that it chamfers. If you want to keep the full original lines when you add the chamfer line, choose the Trim option and choose No Trim. Use the Multiple option to continue the prompts and chamfer several corners in one command. The Undo option lets you undo your last chamfer and try again.

STEPS: Chamfering Lines

The FILLET command creates rounded corners, replacing part of two lines with an arc. Fillets are often used in mechanical drawings. In certain cases, you can use FILLET instead of the ARC command to create arcs. As with CHAMFER, you can fillet lines, xlines, rays, and polylines — they can even be parallel. You can also fillet circles, arcs, elliptical arcs, and ellipses.

The FILLET command defines the fillet arc by its radius, as shown in Figure 10.32.

Figure 10.32. A fillet consisting of two lines and an arc.

Like chamfering, filleting is a two-step process. First you define the radius of the fillet arc. Then you select the two lines that you want to fillet. You cannot select objects before the FILLET command.

To fillet, follow these steps:

By default, FILLET trims the original lines that it fillets, but the FILLET command recalls the last setting you used. If you want to keep the full original lines when you create a fillet, right-click and choose the Trim option, and then choose No Trim.

Filleting with a zero radius gives the same results as chamfering with distances set to zero. (See the previous section on chamfering.) If your existing settings are non-zero, you can press Shift as you select the second object to create a square corner.

The order in which you select the two objects to be filleted is not important. However, where you pick the objects is quite important. If two objects intersect, the command keeps the objects on the same side of the intersection as your pick point and fillets them. Those parts of the objects on the far side of the intersection are erased.

When you fillet arcs and lines, if more than one fillet is possible, FILLET connects the endpoints closest to your pick points. Filleting circles and lines can produce unexpected results. Sometimes you need to experiment to find the proper pick points.

STEPS: Filleting Objects

Geometric constraints apply to the geometric properties of objects. The basic principle is that the first object that you specify is the base object, and the second object that you specify moves or adjusts in accordance with the constraint. For example, if you have two lines at different angles and use the parallel constraint, the second line will rotate to become parallel with the base object. In most cases, you can specify a specific point on an object to manage the constraint.

To specify a geometric constraint for one or more objects, display the Parametric tab and use the Geometric panel. Each button is an option of the GEOMCONSTRAINT command. Table 10.2 lists the available geometric parameters and their functions.

By default, you see small, semitransparent icons for each geometric parameter. You can turn the display of these icons on and off, or turn them on for specific objects. Choose Parametric tab

If you pass your cursor over an icon, you see the name of the constraint. Also, the objects that it affects appear dashed.

The Auto Constrain feature only adds eight of the possible parameters, omitting Fix, Smooth, Equal, and Symmetric. You can specify which parametric constraints to apply and in which order. To do so, click the dialog box launcher arrow on the Geometric panel's title bar to open the Constraint Settings dialog box, and then click the AutoConstrain tab. The settings are self-explanatory.

For more precision, you can apply dimensional constraints, which apply a constraint based on a number or an equation. For example, you can specify a 4-unit distance between two lines. You can specify the dimensional constraint from scratch, or convert an existing dimension.After you create a dimensional constraint, you can change the constraint's value to modify the affected objects. Dimensional constraints show a lock next to their icon to distinguish them from geometrical constraints.

To apply a dimensional constraint, choose the Parametric tab

The Form option of the DIMCONSTRAINT command lets you choose one of two forms (or formats) to apply to subsequent dimensional constraints that you create:

To change the form of an existing dimensional constraint, select the constraint, display the Properties palette (Ctrl+1), and use the Constraint Form drop-down list.

AutoCAD doesn't let you over-constrain geometry. That means that you can't add more constraints than necessary. If you try to add another constraint, AutoCAD opens a message telling you that applying the constraint would over-constrain the geometry. In this situation, you can back out and add a different constraint, or you can create a reference dimension. A reference dimension is just for show; it doesn't actually constrain objects. You might use a reference dimension to show relationships that other constraints create, or to add a second label in a different location. You can change the reference property of a constraint in the Properties palette. AutoCAD displays reference constraints in parentheses.

AutoCAD gives each dimensional constraint a name and you can create expressions that reference another dimensional constraint. In this way, you can create relationships between objects. For example, the radius of a circle can be one half the distance between two lines. The result is that modifying one object then updates related objects; in the example, changing the distance between the lines would change the radius of the circle. The result is a powerful way to control the geometry of your drawing.

You edit and manage dimensional constraints in the Parameters Manager palette, as shown in Figure 10.37. The Parameters Manager lists existing dimensional parameters. You can modify these parameters and create user parameters. The Name column lists the name of each parameter. AutoCAD assigns a default name when you create a dimensional parameter, but you can change the name. Click a name to highlight it, enter a new name, and press Enter. Names cannot start with a number, contain spaces, or be more than 256 characters.

Figure 10.37. The Parameters Manager palette lets you modify dimensional parameters and create user parameters.

To change a value, you use the Expression column, not the Value column. For example, if you have a dimensional parameter that specifies a distance of 3.0 units and you want to change that value to 4.0 units, click the number in the Expression column so that it's selected, enter a new value, and press Enter. The objects adjust to be in accord with the new constraint.

You can enter expressions in the Expression column. For example, if you want the diameter of a circle to be two times the length of a line, and the parameter for the line is named length, you can enter length*2 for the circle's parameter. Then when you change the line parameter's value, which changes the length of the line, the circle's diameter automatically adjusts accordingly. In this way, you maintain the required relationships among objects.

You can also create user parameters. A user parameter can be a value or expression that you want to use as a basis for another parameter. It can be a number or equation.

STEPS: Using Parametric Constraints to Constrain Objects

Stretching with grips involves understanding how the grip points relate to the object. For example, you cannot stretch a line from its midpoint — if you think about it, there's no way to define in which direction to stretch the line. Also, you cannot stretch a circle, you can only scale it. Aside from these types of limitations, anything goes.

It's easy to move objects with grips. First, choose all the objects that you want to move. Then click any grip to activate it. This becomes the base point. Right-click to open the Grip shortcut menu and choose Move or press the Spacebar once. At the Specify move point or [Base point/Copy/Undo/eXit]: prompt, use any method to specify the second point. The selected objects move. The other options work as follows:

Rotating with grips is very similar to using the ROTATE command. First, choose all the objects that you want to rotate. Then click any grip to activate it. This becomes the base point. Right-click to open the Grip shortcut menu and choose Rotate. At the Specify rotation angle or [Base point/Copy/Undo/Reference/eXit]: prompt, type in a rotation angle or pick a point to rotate the objects. The other options work as follows:

Scaling with grips is very similar to using the SCALE command. First, choose all the objects that you want to scale. Then click any grip to activate it. This becomes the base point. Right-click to open the Grip shortcut menu and choose Scale. At the Specify scale factor or [Base point/Copy/Undo/Reference/eXit]: prompt, type a scale factor to scale the objects. The other options work as follows:

Mirroring with grips is similar to using the MIRROR command. First, choose all the objects that you want to mirror. Then click any grip to activate it. This becomes the first point of the mirror line. Right-click to open the Grip shortcut menu. Choose Mirror. At the Specify second point or [Base point/Copy/Undo/eXit]: prompt, specify the second point of the mirror line to mirror the objects.

The other options work as follows:

STEPS: Editing with Grips

You can turn grips on and off and customize their size and color. Choose Application Button

By default, grips are enabled. Also by default, grips are turned off for blocks. (Chapter 18 covers blocks.) When grips are off for blocks, you see only one grip when you select a block; this is its insertion point. When grips for blocks are on, you see all the grips you would normally see for objects.

In the Grips section, you can choose the colors that you want for unselected and selected (hot) grips. Click the drop-down lists to choose a color.

The Grip Size section lets you drag the slider bar to set the size of the grips. Click OK after you have made the desired changes.

Figure 10.42. Use the Selection tab of the Options dialog box to customize grips.

By default, when you select an object, the Quick Properties palette appears, displaying some basic properties of the object, such as its layer, color, and linetype. Other properties that appear depend on the type of object. For example, you see the length of a line, as shown in Figure 10.43. To change an object's properties, enter or choose a new value in the Quick Properties palette. If you select more than one object, you see properties that apply to all the selected objects.

Figure 10.43. The Quick Properties palette shows you an object's properties in a small space and allows you to change those properties.

Right-click any blank area on the palette for further configuration:

The rollover tooltip is a smaller version of the Quick Properties palette that appears when you hover your cursor over an object, without selecting it. You can't change properties in the rollover tooltip; they're just for your information. You can customize which properties appear, and synchronize the tooltip, with the Quick Properties palette; see Chapter 33 for more information.

The Properties palette displays an extended list of the properties of selected objects. You can also use the Properties palette to change the properties of objects.

Figure 10.45. Use the Properties palette to edit objects and their properties.

The auto-hide feature of the Properties palette makes it easy to work with the palette open all the time. Whenever the cursor moves off the palette, it collapses to just display the title bar. To auto-hide the palette, right-click the title bar and choose Auto-hide. You can also dock it; choose Anchor Left or Anchor Right from the title bar's shortcut menu. The Allow Docking item should also be checked; if it isn't, choose it from the same shortcut menu.

You can use the Properties palette to directly edit objects and to edit other object properties as well:

To change values in the Properties palette, do one of the following:

The information that you see in the Properties palette depends on the object selected. If you select more than one object, the palette shows properties that are common to those objects.

The Properties palette has three buttons in its upper-right corner: the Toggle Value of PICKADD Sysvar button, the Select Objects button, and the Quick Select button.

The Toggle Value of PICKADD Sysvar button turns PICKADD on and off. PICKADD changes how you select more than one object. When it's on (set to 1), which is the default, you can continue to select objects and they're added to the selection set. When it's off (set to 0), you need to press Shift to add objects to the selection set; otherwise, selecting an object deselects previously selected objects. Here's how to change the PICKADD variable:

As its name suggests, Quick Select is a quick, flexible, and simple way to create object selection filters. Use the FILTER command, which is covered in the following sections, to create more-complex filters or when you want to save filtering criteria for future use.

Start Quick Select in one of these ways:

The Quick Select dialog box opens, as shown in Figure 10.46.

Figure 10.46. Use the Quick Select dialog box to quickly create a selection set of objects based on specified criteria.

To create a filter, start at the top of the dialog box and work your way down. Here's how it works:

Click OK to select the objects that meet your criteria, and close the dialog box. You can start a command and use the selection set. If the command must be started before selecting objects, you can use the Previous option (type p

Note

The Express Tools include two commands to create filtered selection sets. Type fastselect

The advantage of using the FILTER command over Quick Select is that you can create more-complex filters and save them.

To create a filter, type filter

Creating a single filter

Use the Select Filter section of the dialog box to specify a filter. The drop-down list lists all the possible filters. Click the arrow to display the drop-down list. You can choose from several types of items:

• Objects

• Object properties such as color or layer

• Object snaps such as arc center or circle radius

• Logical operators such as AND, OR, and NOT (these logical operators combine filter specifications in various ways)

The first step is to choose a filter. For example, to create a filter that chooses all lines, choose Line from the drop-down list. If the item chosen does not need any further clarification, click Add to List. The filter appears in the box at the top of the dialog box. This filter would appear as Object = Line.

Many filters require a value. You have two ways to enter a value:

• If you choose an object that can be listed, the Select button becomes active. Click it and choose the value that you want. For example, if you choose Color or Layer, you can choose from a list of colors or layers.

• If you choose an object that can have any value, the boxes below the drop-down list become active. They are labeled X, Y, and Z, but this is misleading. These boxes are used for X, Y, and Z coordinates only when you choose a filter requiring coordinates, such as Viewport Center. In most cases, you use the X text box to give the filter a value. In this situation, the Y and Z boxes are not used. For example, if you choose Text Height, you type the height in the X box.

Keep in mind that you don't always want to specify that a filter equals a value. For example, if you want to create a filter that selects all circles with a radius less than 0.75, then when you choose Circle Radius, the X box becomes active. Click the arrow to display the drop-down list of relational operators and then choose one. Table 10.3 lists the relational operators.

Table 10.3. Relational Operators in the Object Selection Filters Dialog Box

Operator	Definition
=	Equal to
!=	Not equal to
<	Less than
<=	Less than or equal to
>	Greater than
>=	Greater than or equal to
*	Equal to any value

Adding a second filter

To add a second filter, you first decide on the relationship between the first and the second filters and then assign a logical operator. Logical operators always come in pairs — when you begin one operator, you must also end it. The logical operators are at the end of the drop-down list of filter objects.

Note

When two or more filters are listed without logical operators, the filter calculates them as if they were grouped with the AND operator. This means that the filter selects only objects that meet all the criteria specified.

Table 10.4 explains the four logical operators, which are called grouping operators because they group filter specifications together. The Example column explains the results of two filter specifications: Color = 1-Red and Object = Circle.

Table 10.4. Logical (Or Grouping) Operators Used for Selection Filters

Operator	Explanation	Example
AND	Finds objects that meet all criteria.	Finds red circles.
OR	Finds objects that meet any of the criteria.	Finds all red objects and all circles.
XOR	Finds objects that meet one criterion or the other but not both. Requires two criteria between Begin XOR and End XOR.	Finds red objects that are not circles and circles that are not red.
NOT	Excludes objects that meet the criteria. May have only one criterion between Begin NOT and End NOT.	If the NOT operator groups the Object = Circle filter, then it finds all red objects that are not circles.

Click Substitute and choose a saved filter to insert a saved filter into the filter you're currently defining. To add filters based on existing objects, choose Add Selected Object. This action adds all the properties of the object to the filter definition, which is often more than you want.

Figure 10.47 shows a filter that selects all lines and all polylines. The XOR operator finds objects that meet one criterion or the other but not both. Obviously, no object can be both a line and a polyline. This is a good example of a filter that you cannot create by using Quick Select.

Figure 10.47. A filter that selects all lines and all polylines.

After you've completed the filter, you should save it. Even if you don't think you'll use it again, you may make an editing error in the drawing while using it and have to go back to it. To save a filter, type a name in the Save As text box and click Save As.

You edit a listed filter by using three buttons:

To choose a named filter to edit, choose it from the Current drop-down list.

You can use filters in two ways. Most often, you choose a command first and then realize that you need a filter to select the objects. In this situation, follow these prompts:

Select objects: 'filter 

Define the filter in the Object Selection Filters dialog box. Click Apply.
Applying filter to selection.
Select objects: Type all 
 or use a large selection window to select all the objects that you want to consider in the filter.
x found
Select objects: 

Exiting filtered selection. x found
Select objects: 

The command's usual prompts then continue.

Alternatively, you can start the FILTER command and define the filter. Click Apply. At the Select objects: prompt, type all or use a selection window. Press Enter to end object selection. Then start the editing command and use the Previous selection option to select the filtered objects.

STEPS: Using Selection Filters

To create or modify a group, type group

Figure 10.48. The Object Grouping dialog box.

To create or modify a group in AutoCAD LT, type group

Figure 10.49. Use the Group Manager window to create and manage groups in AutoCAD LT.

Using a group is very simple. If a group is selectable, just pick any object in the group to select all the objects in the group. You can then edit the objects in the group as a whole. If you need to temporarily edit one object in a group, then turn off the group's selectability, as described in the previous sections.

You can change the selectable status of all groups in your drawing by choosing Application Button