Creating a Symbol

Creating a Symbol
To save a drawing as a symbol, you use the Block tool. In word processors, the term
block
refers to
a group of words or sentences selected for moving, saving, or deleting. You can copy a block of text
elsewhere within the same file, to other files, or to a separate file or disk for future use. AutoCAD
uses blocks in a similar fashion. In a file, you can turn parts of your drawing into blocks that can be
saved and recalled at any time. You can also use entire existing files as blocks.
You’ll start by opening the file you worked on in the last chapter and selecting the objects that
will become a block:
1.
Start AutoCAD, and open the existing
Bath
file. Use the one you created in Chapter 3,
or open
04-bath.dwg
sample file from the Sybex web site. Metric users can use the
04-
bath-metric.dwg
file. The drawing appears just as you left it in the last session.
2.
In the Draw toolbar, click the Make Block tool or type
B
↵
, the keyboard shortcut for the Make
Block tool, to open the Block Definition dialog box. You can also choose Draw 
Block 
Make.



3.
In the Name text box, type
Toilet
4.
In the Base Point group, click the Pick Point button. This option enables you to select a base
point for the block by using your cursor. (The
insertion base point
of a block is a point of reference
on the block that is used like a grip.) When you’ve selected this option, the Block Definition
dialog box temporarily closes.
TIP
Notice that the Block Definition dialog box gives you the option to specify the X, Y, and Z coordinates
for the base point instead of selecting a point.
5.
Using the Midpoint osnap, pick the midpoint of the back of the toilet as the base point.
Remember that you learned how to set up Running Osnaps in Chapter 3; all you need to do
is point to the midpoint of a line to display the Midpoint Osnap marker and then left-click
your mouse.



After you’ve selected a point, the Block Definition dialog box reappears. Notice that the X,
Y, and Z values in the Base Point group now display the coordinates of the point you picked.
For two-dimensional drawings, the Z coordinate should remain at 0.
Next, you need to select the objects you want as part of the block.
6.
Click the Select Objects button in the Objects group. Once again, the dialog box momentarily
closes. You now see the familiar object-selection prompt in the Command window, and the
cursor becomes an Object Selection cursor. Click a point below and to the left of the toilet.
Then, use a selection window to select the entire toilet. The toilet is now highlighted

WARNING
Make sure you use the Select Objects option in the Block Definition dialog box to
select the objects you want to turn into a block. AutoCAD lets you create a block that contains no
objects. If you try to proceed without selecting objects, you’ll get a warning message. This can
cause confusion and frustration, even for an experienced user.
7.
Press
↵
to confirm your selection. The Block Definition dialog box opens again.
8.
Select Inches from the Block Unit drop-down list. Metric users should select Centimeters.
9.
Click the Description list box, and enter
Standard Toilet
.
10.
Make sure the Retain radio button in the Objects group is selected, and then click OK. The
toilet drawing is now a block with the name Toilet.
11.
Repeat the blocking process for the tub, but this time use the upper-left corner of the tub as the
insertion base point and give the block the name
Tub
. Enter
Standard Tub
for the description.
TIP
You can press
↵
or right-click the mouse and choose Repeat Block from the shortcut menu to
start the Make Block tool again.
When you turn an object into a block, it’s stored in the drawing file, ready to be recalled at any
time. The block remains part of the drawing file even when you end the editing session. When you
open the file again, the block is available for your use. In addition, you can access blocks from other
drawings by using the AutoCAD DesignCenter and the Tool palettes. You’ll learn more about the
DesignCenter and the Tool palettes in Chapter 27.
A block acts like a single object, even though it’s really made up of several objects. One unique
characteristic of a block is that when you modify it, all instances of that block are updated to reflect
the modifications. For example, if you insert several copies of the toilet into a drawing and then
later decide the toilet needs to be a different shape, you can edit the Toilet block, and all the other
copies of the toilet are updated automatically.
You can modify a block in a number of ways after it has been created. In this chapter, you’ll learn
how to make simple changes to individual blocks by modifying the block’s properties. For more
detailed changes, you’ll learn how to redefine a block after it has been created. Later, in Chapter 17,
you’ll learn how to use the Block Editor to make changes to blocks.