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Specify Units, Angles and Scale

May 20, 2011

Specify the units of measurement you want to use, their format, and other conventions.

Determine Units of Measurement

When you start drawing, you specify the units of measurement, their formats as well as the number of decimal fraction.

Set the Units Format

     You can set the display format of the unit. These formats include scientific, decimal, engineering, architectural and fractional notation. To enter architectural feet and inches format, you can indicate feet using the prime symbol ( ' ), for example, 72'3. You do not need to specify inches by entering quotation marks ( " ).

    You can set the unit type and precision in the Quick Setup wizard, the Advanced Setup wizard, or the Units Control dialog box. These settings control how your coordinate, offset, and distance entries are interpreted, and how coordinates and distances are displayed.

    The input format of three-dimension coordinates is the same as the input format of the two-dimension coordinates: scientific, decimal, engineering, architectural and fractional notation.

    The unit format for creating and listing objects, measuring distance and displaying coordinate locations is different from the dimension units setting used in creating dimension values.

     With ZWCAD, you typically draw at full size (1:1 scale), and then set a scale factor when you print or plot your drawing. Before you begin drawing, however, you need to determine the relationship between drawing units and real world units.

      For example, you can decide whether one linear drawing unit represents an inch, a foot, a meter, or a mile. In addition, you can specify the way the program measures angles. For both linear and angular units, you can also set the degree of display precision, such as the number of decimal places or smallest denominator used when displaying fractions. The precision settings affect only the display of distances, angles, and coordinates. ZWCAD always stores distances, angles, and coordinates using floating point accuracy.

Open drawing units dialog

  • Choose Format > Units.

Command line UNITS

Convert Drawing Units

       When you create a new drawing in one system of measurement (imperial or metric) and then change to the other system, use SCALE to scale the model geometry by the appropriate conversion factor to obtain correct distances and dimensions. The conversion is shown as follows:

      For example, to convert inches to centimeters, you scale the drawing by a factor of 3.25. To convert from centimeters to inches, the scale factor is 1/3.25 or about 0.3077.

Set Angle Conventions

        You can specify the location for angle 0 and the positive direction for the angle measurement: clockwise or counterclockwise. You can also specify the format and the number of decimal fraction. Shown as the following illustrations:

  • Specify the measurement unit and precision. The units include grad, radian, surveyor's unit and degree, minute and second.

  • Specify where the angle measurement starts from: east, west, south, north or others. For example, to enter a coordinate relative to the current coordinate for a property line that is 54 feet, 7 inches long with a bearing of 60 degrees north, 12 minutes, 6 seconds east, enter @54'7"<n60d12'6"e.

  • Specify the positive direction: counterclockwise or clockwise. The angle 0 can be set to any location.

Setting scale factors

       Instead of drawing to a particular scale, you draw everything full size in the program. Although it's a good idea to keep your scale factor in mind when setting up a drawing, you don't need to set the scale until you print it. For example, when you draw a mechanical part 40 inches in length with ZWCAD, you actually draw it as 40 inches, rather than applying a scale factor as you draw. When you print your drawing, you can assign the scale at which the drawing is to print.

       Scale, however, does affect the way a few elements such as text, arrows, or linetypes print or plot in your drawing. For these, you can make adjustments when you first set up your drawing so that they print or plot at the correct size. For example, when you draw text, you need to determine the text size so that when you print it later at a particular scale, the text height is correct.

        After you determine the eventual scale of your finished drawing, you can calculate the scale factor for the drawing as a ratio of one drawing unit to the actual scale unit represented by each drawing unit. For example, if you plan to print your drawing at 1/8" = 1'-0", your scale factor ratio is 1:96 (1/8" = 12" is the same as 1 = 96). If you want your printed scale to be 1 inch = 100 feet, your scale factor ratio is 1:1200.

       The following table shows some standard architectural and engineering scale ratios and equivalent text heights required to create text that measures 1/8 inch high when you print the drawing at the specified scale.


Standard scale ratios and equivalent text heights
Scale Scale factor Text height
1/16" = 1'-0" 192 24"
1/8" = 1'-0" 96 12"
3/16" = 1'-0" 64 8"
1/4" = 1'-0" 48 6"
3/8" = 1'-0" 32 4"
1/2" = 1'-0" 24 3"
3/4" = 1'-0" 16 2"
1" = 1'-0" 12 1.5"
1 1/2" = 1'-0" 8 1"
3" = 1'-0" 4 0.5"
1" = 10' 120 15"
1" = 20' 240 30"
1" = 30' 360 45"
1" = 40' 480 60"
1" = 50' 600 75"
1" = 60' 720 90"
1" = 100' 1200 150"

       You can use these scale factors to predetermine the size of your drawing to make sure that it fits on a specific size paper when you print it. You control the size of your drawing by the drawing limits. To calculate the drawing limits to match the size of your paper, multiply the dimensions of your paper size by your scale factor.

      For example, if the paper you use to print measures 36 inches x 24 inches and you print your drawing at 1/8" = 1'-0" (in other words, using a scale factor of 96), the size of your drawing measured in drawing units is 36 x 96 (or 3,456 units) wide and 24 x 96 (or 2,304 units) high.

      Keep in mind that you can print the finished drawing at any scale, regardless of the scale factor you calculate. You can also print on paper of a different size and use the Layout tabs to create different views of your drawing and to position and scale those views differently. The scaling factor is not related to the size of the entities you draw; it simply provides a preliminary guide to help you establish the text height and drawing limits when you begin your drawing. You can change the text height and drawing limits at any time.


Apply scale factors

You can set the following factor to determined whether the drawing is plotted on the model space or paper space.

  • Text. Sets text height in the text style (STYLE) or in the process of creating text. The text plotted height should be set in proportion to scale factor in model space. The text created on the layout should be set at 1:1.

  • Dimension. Sets dimension scale in the dimension style (DIMSTYLE) or through system variable DIMSCALE.

  • Linetype. To plot objects from the Model tap, use system variables CELTSCALE and LTSCALE to set scale for noncontinuous lines. To plot objects from a layout (paper space), use system variable PSLTCALE.

  • Hatch. Sets hatch scale in the Boundary Hatch dialog box or through system variable HPSCALE.

  • View. When you plot a drawing from a layout, you may need to use ZOOM xp command, where xp is a ratio that is relative to the paper size ( scale factor of reciprocal).

Setting the text height

       The text height setting controls the height of text, measured in drawing units. Set this value initially so that text used for your most common annotations, when scaled to the size at which you will print a drawing, measures 1/8-inch high on the printed drawing.

      For example, if you plan to print your drawing at 1/8" = 1'-0" and you want your text to be 1/8-inch high in the final drawing, create that text 1 foot high (in your realworld drawing units) so that when you print it, it appears 1/8-inch high on the paper.

      You must create text 4 feet high that you want to print 1/2-inch high.

To set the text height

  1. Choose Format > Text Style.

  2. Type a value in the Text Height text under Text Measurements.

  3. Press OK to save the current settings.

NOTE The default text height applies only if the current text style height is 0.0. Otherwise, the text height for the current style takes precedence.

Commands Reference

UNITS: Controls coordinate and angle display formats and precision

System Variables Reference

UNITMODE: Controls the display format for units

ANGBASE: Sets the base angle to 0 with respect to the current UCS

ANGDIR: Sets the direction of positive angles

AUNITS: Sets units for angles

AUPREC: Sets the number of decimal places for all read-only angular units displayed on the status line, and for all editable angular units whose precision is less than or equal to the current AUPREC value  

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