Drawing the tub and toilet in Chapter 3 may have taken what seemed to you an inordinate amount of time. As you continue to use AutoCAD, however, you will learn to draw objects more quickly. You will also need to draw fewer of them because you can save drawings as symbols to be used like rubber stamps, duplicating drawings instantaneously wherever they are needed. This saves you a lot of time when you’re composing drawings,
To make effective use of AutoCAD, you should begin a symbols library of drawings you use frequently. A mechanical designer might have a library of symbols for fasteners, cams, valves, or any type of parts for his or her application. An electrical engineer might have a symbols library of capacitdrs, resistors, switches, and the like. A circuit designer will have yet another unique set of frequently used symbols. This book’s companion CD-ROr. [contains a variety of ready-to-use symbols libraries. Check them out-you’re hkely to find some you can use. In Chapter 3, you drew two objects-a bathtub and a toilet-that architects often use. In this chapter, you will see how to create symbols from those drawings. You will also learn about layers and how you can use them to organize information.
A symbols lrbrary was a crucial part of the production of the San Francrsco Main Llhrary construction documents. Shown here is a portion otan AutoCAD floor plan of the library where some typical symbols were used. Notice the familiar door symbols, like the door you created In Chapter 2 And yes, there are even toilets in the lower half of the plan in the public restroorns Thp method for drawing the wide flange demonstrated <Itthe end 01 Chapter 3 IS ,Imllilr to the one thill was used to create the I-beam column symbols shown here. Symbol use isn’t restricted to the uuddlflYcomponents. Room ‘lumber labels, diamondshaped interior elevation reference symbols, and the hexagonal column grid symbols are all common to an architectural drnwmq, regardless of the project’s size. As you wor+ through this chapter, keep IIImind that all of the symbols used in tile library draw were created using the tools presented here.
Creating a Symbol
To save a drawing as a symbol, you use the’ Block tool. In word processors, the term block refers to a gro’up of words or sentences selected for moving, saving, or deletion. A block of text <;anbe copied elsewhere within the same file, to other files, or to a separate file on disk for future use. AutoCAD uses blocks in a similar fashion. Within a file, you can turn parts of your drawing into blocks that can be saved andrecalled at any time. You can aha use entire existing files as blocks.
1. Start AutoCAD and open the existing Bath file. Use the one you created in Chapter 3 or open 04-BATH. dwg on the companion CD-ROM. The drawingappears just as you left it in the last session.
2. In the Draw toolbar, click the Make Block tool or type B.J, the keyboard shortcut for the Make Block tool.
3. Type Toilet.J into the Name input box.
4. In the Base Point button group of the dialog box, click the Pick Point button.’
This option enables you to select a base point for the block using your cursor. (The insertion base point of a block is similar to the base point you used as a handle on an object in Chapter 2.) When you’ve selected this option, the Block Definition dialog box temporarily disappears.
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 some Running Osnaps all YOll need to do is point to the midp()m~ of,a line to display the Midpoint Osnap marker, and then left-click your mouse. Once you’ve selected a point the Block Definition dialog box reappears. Notice that the x,
y, and z values in the Base Point button group now display the coordinates of the point you picked.
6 Next, you need to select the actual objects that you want as part of the block. Click the Select Objects button in the Objects button group. Once again, the dialog box momentarily disappears. 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 window the entire toilet. The toilet is now highlighted.
7. Press.J to confirm your selection. The Block Definition dialog’ box appears again.
8 Select Inches from the Insert Units 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 button group is checked, 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.
When you turn an object into a block, it is stored within the drawing file, ready to be recalled at any time. TIle block remains part of the drawing file even when you end the editing session. When you open the file again, the block will be available for your use. In addition, you can access blocks from other drawings using a feature called the AutoCAD DesignCenter. You’ll learn more about the DesignCenter later.
A block acts like a single object. even though it is really made up of several objects. One unique characteristic of a block is that when you modify a block, all instances of that block are updated to reflect the modifications. For example, you can insert several copies of the toilet into a drawing, then later, if you decide the toilet needs to be of a different shape, you can edit the Toilet block and all of the other copies of the toilet are updated automatically.
In earlier versions of AutoCAD, you had to redraw a block and then redefine the block using the steps in the previous exercise. AutoCAD 2000 offers a new, ‘ easier way to make changes to blocks called In-Place Xref and Block Edit. You’ll learn more about this fea~e later in this chapter.