One of the first tasks in setting up a drawing is to choose the unit type. Units define how objects are measured. You can save the unit type in a template.

Note

When you start AutoCAD or AutoCAD LT for the first time, the Initial Setup dialog box appears and prompts you to select your industry and a template. This can affect your units. For example, if you choose the Architecture option on Page 1 and a template suitable for your industry on the last page, whenever you start a new drawing, your units will be architectural. You can change these settings at any time by choosing Application Button

The coordinates you use in AutoCAD or AutoCAD LT are measured in units that can represent any real-world measurement, such as inches or millimeters. A surveyor or city planner might even use miles or kilometers as the base unit. However, different disciplines have customs that express units differently, and you should use the unit type appropriate for the type of drawing you're creating. This ensures that everyone involved understands the drawing. AutoCAD and AutoCAD LT offer five types of units, as shown in Table 5.1. The sample measurement column shows how a line 32.5 units long would be displayed in the various unit types.

Notice how the engineering and architectural units translate a line of 32.5 units into feet and inches. Engineering and architectural units assume a unit of 1 inch, unlike the other unit types, which can represent any measurement.

The unit type affects how coordinates are shown on the status bar and how information about objects is listed. You generally input coordinates by using the type of units you've chosen, although in some cases you can input coordinates in another unit type.

Setting the drawing units

When you know the units you want to use, you set them in the Drawing Units dialog box. To set the units, choose Application Button

Warning

AutoCAD and AutoCAD LT round off measurements to the nearest precision value you choose. Say that you choose a precision of two decimal places, using decimal units. You want to draw a line so that it is 3.25 units long, but when you type the coordinate, by accident you press the 4 key at the end, resulting in a line 3.254 units long. This line is displayed as 3.25 units long, making it difficult for you to spot the error. Therefore, setting a higher precision than you need to show is a good idea.

Figure 5.1. The Drawing Units dialog box.

Setting the angle type

As with units, your choice of angle type depends on your profession and work environment. Decimal Degrees is the default. Table 5.2 lists the types of angles.

Table 5.2. Angle Types

Angle Type Name	Sample Measurement	Description
Decimal Degrees	32.5	Degrees, partial degrees in decimals
Deg/Min/Sec	32°30′0″	Degrees, minutes, and seconds
Grads (gradians)	36.1111g	Gradians
Radians	0.5672r	Radians
Surveyor	N 57d30′ E	Surveyor (directional) units

Note

A minute is

To set the angle type, choose the option you want from the Type drop-down list of the Angle section of the Drawing Units dialog box (shown in Figure 5.1).

Note

Changing these angle settings does not automatically change the way your dimension annotations appear. Use the Dimension Style Manager, which is discussed in Chapter 15, to change dimensions.

Setting the angle measure and direction

By convention, degrees increase in a counterclockwise direction, and you measure angles so that 0 degrees starts to the right, also called the East direction. To change the angle direction, click Clockwise in the Drawing Units dialog box. To change the direction of 0 degrees, click Direction to open the Direction Control dialog box, as shown in Figure 5.2.

Figure 5.2. The Direction Control dialog box.

Here you can choose to have 0 degrees start in a direction other than East. You can also choose Other and type any other angle or click the Pick an Angle button to pick two points on your screen that specify an angle. Click OK to close the Direction Control dialog box. Click OK to close the Drawing Units dialog box.

Note

Changing the angle direction affects what happens when you input angles and what you see in the coordinate display. It does not change the absolute coordinates, which are set according to the User Coordinate System (UCS). Chapter 8 covers using and customizing UCSs.

If you are using Dynamic Input, the angle that you see in the Dynamic Input tooltip never goes above 180°. This angle in the tooltip represents the angle to your current point and goes from 0° to 180° in both the clockwise and counterclockwise directions.

Note

At the bottom of the Drawing Units dialog box, you can choose units for lighting. See my discussion of lighting in Chapter 25 for more information.

STEPS: Setting Drawing Units

1. Begin a new drawing by using the acad.dwt or acadlt.dwt template. Close any palettes that may be open. If Dynamic Input isn't on, click the Dynamic Input button on the status bar. This exercise assumes that you have input of coordinates set to relative coordinates, the default setting. (For more information, see Chapter 4.)

2. Save the drawing as ab05-01.dwg in your AutoCAD Bible folder.

3. Choose Application Button

   

4. In the Length section, choose Architectural.

5. Click the arrow to the right of the Precision drop-down list in the Length section. Choose 0′-0 1/8″.

6. In the Angle section, choose Deg/Min/Sec.

7. In the Precision box, choose 0d00′.

8. In the Units to Scale Inserted Content drop-down list, set the units to Inches.

9. Click OK.

10. Choose Home tab

    

    Specify first point: 2,2 
    
    Specify next point or [Undo]: 1′<0 
    
    Specify next point or [Undo]: 6-3/4<153 
    
    Specify next point or [Close/Undo]: Right-click and choose Close.

11. Choose View tab

    

Note

You would not actually use Deg/Min/Sec for angles in an architectural drawing, but the exercise gives you the opportunity to set the angular units.

You can specify the area of your drawing, also called the limits. The drawing limits are the outer edges of the drawing, specified in X,Y units. You need to set only the width and length of the drawing. Together, these two measurements create an invisible bounding rectangle for your drawing.

Almost universally, the lower-left limit is 0,0, which is the default. Therefore, the upper-right corner really defines the drawing size. Remember that you typically draw at life size (full scale). Therefore, the size of your drawing should be equal to the size of the outer extents of what you're drawing, plus a margin for a titleblock (if you plan to add one), annotation, and dimensioning. If you want to show more than one view of an object, as is common in both architectural and mechanical drawings, you need to take this into account.

To decide on the upper-right corner limits (the width and length) for your drawing, you need to consider what the drawing units mean for you. Generally, the smallest commonly used unit is used, often inches or millimeters. Therefore, if you're drawing a plan view of a house that is approximately 40 feet across (in the X direction) by 30 feet deep (in the Y direction), this translates to a top-right corner of 480,360. Adding room for a titleblock brings you to about 500,380.

The limits define an artificial and invisible boundary to your drawing. However, you can draw outside the limits. The limits affect the size of the grid, when displayed. (See Chapter 4 for a discussion of the grid.) The ZOOM command with the All option also uses the limits, but only if no objects are outside the limits. (See Chapter 8 for a discussion of the ZOOM command.)

To set the drawing limits, type limits

You need to consider the fact that your drawing will most likely be plotted onto a standard paper (sheet) size. The standard orientation for drafting (and the default for most plotters) is landscape orientation, meaning that as you look at the drawing, the paper is wider than it is tall. Figure 5.3 shows an example. To scale a drawing onto a piece of paper in a pleasing manner requires a rectangular shape that somewhat resembles the proportions of standard paper sizes.

Figure 5.3. Drawings are usually oriented horizontally, as in this example.

In addition, although you specify the scale at plotting time, it helps to be aware at the outset of the scale you'll use when plotting your drawing. One important reason for establishing the scale at the beginning is to ensure that text, whether annotations or dimensions, is readable in its final plotted form. Applying a scale ensures that text remains a reasonable size even as the rest of the drawing is scaled up or down. Scale also affects linetypes that contain dots or dashes.

Some drawings are not scaled. Examples are electrical or electronic schematics, piping diagrams, and railroad schematics. These drawings are representations of electrical or electronic connections but do not resemble the actual physical object that will eventually be created from the drawing. These drawings can be any size as long as they are clear and organized.

When determining your scale to fit a drawing on a sheet of paper, be aware that a plotter cannot print on the entire sheet. A certain amount of the margin around the edge is not available for drawing. The plotter's manual can let you know the width of this unprintable margin. On average, you can assume a half-inch margin on each side; thus you should subtract 1 inch from both the length and width sheet measurements to determine the actual drawing space. Table 5.3 shows standard U.S. sheet sizes.

Table 5.4 lists standard metric sheet sizes.

Working with scale formats

A scale is often indicated in the format plotted size=actual size or plotted size:actual size. Because you draw at actual size, the actual size is also the drawing size. For example, a scale of ¼″=1′ means that ¼ inch on the drawing, when plotted out on a sheet of paper, represents 1 foot in actual life — and in the drawing. This is a typical architectural scale. A windowpane 1 foot wide would appear ¼-inch wide on paper.

From the scale, you can calculate the scale factor. You use the factor when you set the size for text (see Chapter 13) or for dimensions (see Chapter 15). To do this, the left side of the scale equation must equal 1, and the two numbers must be in the same measurement (for example, both in inches). This requires some simple math. For ¼″=1′, you would calculate as follows:

¼″=1′
1″=4′	Both sides of the equation multiplied by 4
1″=48″	4′ converted to 48″

Therefore, the scale factor is 48. This means that the paper plot is

In mechanical drawing, you might draw a metal joint that is actually 4 inches long. To fit it on an 8½-x-11-inch sheet of paper, you could use a 2″=1″ scale, which means that 2″ on the paper drawing equals 1″ in actual life and the drawing. Calculate the scale factor:

2″=1″

1″=½″

The scale factor is ½. This means that the paper plot is twice the real size.

Most professions use certain standard scales. Therefore, you do not usually have a choice to pick any scale you want, such as 1″:27′. Instead, the conventions of your profession, client, or office dictate a choice of only a few scales. Some typical architectural scale factors are:

• 192: 1/16″ = 1′

• 96: 1/8″ = 1′

• 48: 1/4″ = 1′

• 24: 1/2″ = 1′

• 12: 1″ = 1′

Civil engineering scales are somewhat different and range to larger sizes — a bridge is bigger than a house. Some typical scale factors are 120 (1″ =10′) and 240 (1″ =20′).

Metric scales can be used for any purpose. Example scale factors are 10000 (1mm = 10 meters), 5000 (1mm = 5 meters), 1000 (1 mm = 1 meter), or 100 (1cm = 1 meter).

Using annotative scales

You can assign an annotative property to certain objects so that they automatically resize to the proper scale when you lay out the drawing for plotting. The following types of objects can be annotative:

• Text (see Chapter 13)

• Dimensions and leaders (see Chapters 14 and 15)

• Hatches (see Chapter 16)

• Blocks and attributes (see Chapter 18)

You would especially use annotative scaling when you need to display your drawing at more than one scale. For example, you might display the entire drawing at one scale and a detail at another scale. (See Chapters 13, 14, 15, 16, 17, and 18 for more detailed information on annotative styles and objects.)

Using annotative objects avoids the necessity to manually figure out how large these objects need to be; when you scale them, they will be the proper size. For example, if your drawing scale will be 1:48, and you want your text to be ¼″ high, then you would need to multiply the desired height of the text (¼″) by the scale factor to get a text height of 12. However, by setting the annotative scale for the text to 1/4″ = 1′-0″, you can simply set the height of the text to ¼″ and not worry about the calculations.

The procedure for creating annotative objects differs somewhat for each type of object, but the overall process is the same:

1. If necessary, create an annotative style and make it current. Annotative text, dimensions, and multileaders require an annotative style.

2. Decide on the scales that you will use for each object. For example, you might have two text objects each at a different scale, or one text object that you need to display at two different scales.

3. 
4. 

5. Create the object.

6. When you're ready to plot, you can set the desired annotative scale, and plot. You can also create viewports and set their scale. See Chapter 17 for details and an exercise using annotative objects.

If you want one object to have more than one scale, you can add an annotative scale to it. Follow these steps:

1. Select the object and right-click in the drawing area.

2. Choose Annotative Object Scale

   
   

   Figure 5.4. The Annotation Object Scale dialog box enables you to add an annotation scale to an annotation object.

3. Click Add to display the Add Scales to Object dialog box, where you can choose one or more scales.

4. Click OK twice to close both dialog boxes.

You can also open the dialog box by displaying the Properties palette, clicking the Annotative Scale item, and clicking the Ellipsis button that appears.

Customizing the scale list

You generally choose a scale during the process of laying out a drawing. AutoCAD and AutoCAD LT have a list of scales from which you can choose. You can find this list in several places (which I discuss throughout the book):

• On the Annotation Scale list on the status bar, as mentioned earlier

• In the Add Scales to Object dialog box, also mentioned earlier

• In the VP Scale list of the status bar, when you select a viewport (see Chapter 17)

• In the Plot Scale drop-down list section of the Page Setup dialog box (see Chapter 17)

• In the Plot Scale section of the Page Setup dialog box (see Chapter 17)

• In the Standard scale item of the Properties palette when a viewport is selected (see Chapter 17)

• In the Sheet Set Manager (AutoCAD only), when placing a view on a layout (see Chapter 26)

You might use unusual scales in your office or want a list that includes only the scales that you use. You can customize the scale list for this purpose.

To customize the scale list, choose Annotate tab

Figure 5.5. Use the Edit Scale List dialog box to create your own custom scales.

To add a new scale, click Add. In the Add Scale dialog box, name the scale. The name is what will show on the list. Then define the scale by completing the Paper Units and Drawing Units text boxes. For example, to add a 1:12 scale, you would name the scale 1:12, set the Paper Units to 1 and the Drawing Units to 12.

To delete scales that you don't use, select the scale and click Delete. You can also edit existing scales (select the scale and click Edit), move them up or down in the order of the list, and reset the list (click Reset) to its original status. Click OK when you're done.

Note

AutoCAD 2010 stores the scales list within the drawing file, so this list can vary with the drawing. Scales used in any externally referenced files will also show up in this list, even if they weren't originally set in your host file.

A titleblock is a rectangle that includes spaces for the drawing title, company name, drafter name, and so on. It generally comes with a border that bounds your drawing. Many drawings require titleblocks. You can insert an existing titleblock in two ways:

To find the location of the templates, choose Application Button

A few other items are generally set up in advance and are included in a template. Other chapters of this book cover the following:

If you know that you'll be using snap, grid, and ortho modes (covered in Chapter 4) a lot in certain drawings, and you know the suitable settings for snap and grid, you can set these and save them in a template because these settings are saved with the drawing. In other cases, you might want to leave them off and turn them on only when you need them.

Many settings, such as running object snaps, the type of snap (grid or polar), and the polar distance, are saved in the Windows registry, not in your drawing. As a result, when you open AutoCAD or AutoCAD LT, they're automatically set to the same setting that you had when you last closed the program, regardless of the setting in the drawing. Therefore, you cannot save these settings in a template.

STEPS: Setting Drawing Aids and Creating a Template

The MVSETUP command is used in two different ways: to set up a drawing and to create viewports for paper space layouts (covered in Chapter 17). This command does not exist in AutoCAD LT.

MVSETUP provides a command-line routine to walk you through some of the basic setup functions discussed in this chapter. You can use MVSETUP when you start to customize AutoCAD to set up a drawing from a script file or AutoLISP program (topics covered in Parts VI and VII of this book). To use MVSETUP, type mvsetup

Enable paper space? [No/Yes] <Y>:

Type n

The next prompt lets you enter the units type:

Enter units type [Scientific/Decimal/Engineering/Architectural/Metric]:

Choose the option you want. Then AutoCAD displays a list of scale factors appropriate to the units option you chose. (To see them all, you may have to press F2 to open the AutoCAD Text Window.) At the Enter the scale factor: prompt, type in a numeric scale factor.

Finally, AutoCAD prompts you to set the drawing limits with the following two prompts:

Enter the paper width:
Enter the paper height:

After each prompt, enter a number based on the size of the paper on which you plan to plot. AutoCAD draws a rectangle of the size that you indicated for the drawing limits.

Note

There are two wizards to help you set up a drawing. You need to activate the Startup dialog box to find them. To do so, enter startup

This chapter explained setting up a drawing so that it behaves the way you want it to. You read about:

This chapter ends Part I, "AutoCAD and AutoCAD LT Basics." Now that you know the basics, you can go on to Part II, "Drawing in Two Dimensions." The next chapter covers drawing simple lines, polygons, rectangles, and infinite construction lines.