Setting Dimension Variables

Chapter 9 discussed the various options for dimensioning available through the Dimension Style and other dialog boxes and mentioned that most of these options have equivalent system variables. Later in this appendix you'll find a complete discussion of all elements of the Dimension Style dialog box and how to use it.

This section provides further information about the dimension variables. For starters, Table C.2 lists each variable, its default status, and a brief description of what it does. You can get a similar listing by entering “Dimstyle at the command prompt, and then typing ST to select the Status option. Alternatively, you can use the AutoCAD Help system. This section also discusses a few system variables that do not appear in the Dimension Style dialog box.

Table C.2: Dimension Variables
Dimension Variable	Default Setting	Description
General Dimension Controls
Dimaso	On	Turns partial associative dimension on and off (obsolete).
Dimassoc	2	Turns true associative dimension on and off: 0 = exploded dimension; 1 = pre-2002 associative dimensions; 2 = fully associative dimensions.
Dimsho	On	Updates dimensions dynamically while dragging.
Dimstyle	Standard	Indicates name of current dimension style.
Dimtmove		Sets the way dimension text behaves when moved: 0 = move dimension line with text; 1 = add leader and move text freely; 2 = no leader and move text freely .
Dimupt	Off	Controls user positioning of text during dimension input: 0 = automatic text positioning; 1 = user - defined text positioning allowed.
Scale
Dimasz	0.18 (approx. ³ / ₁₆ ²	Indicates arrow size .
Dimcen	0.09 (approx. ³ / ₃₂ ² ⁾	Indicates center mark size.
Dimlfac	1.0000	Multiplies measured distance by a specified scale factor.
Dimscale	1.0000	Indicates overall scale factor of dimensions.
Dimtsz		Indicates tick size.
Dimtxt	0.18 (approx. ³ / ₁₆ ² ⁾	Indicates text height.
Offsets
Dimdle	²	Indicates the amount the dimension line extends beyond the extension line.
Dimdli	0.38 (approx. ³ / ₈ ² ⁾	Indicates the dimension line offset for continuation or base.
Dimexe	0.18 (approx. ³ / ₁₆ ² ⁾	Indicates the amount the extension line extends beyond the dimension line.
Dimexo	0.0625 or ¹ / ₁₆ ²	Indicates extension line origin offset.
Tolerances
Dimalttz		Controls zero suppression of tolerance values: 0 = leave out zero feet and inches; 1 = include zero feet and inches; 2 = include zero feet; 3 = include zero inches; 4 = suppress leading zeros in decimal dimen- sions; 8 = suppress leading zeros in decimal dimensions.
Dimdec	4	Sets decimal place for primary tolerance values.
Dimlim	Off	When on, shows dimension limits.
Dimtdec	4	Sets decimal place for tolerance values.
Dimtm	²	Indicates minus tolerance.
Dimtol	Off	When on, shows dimension tolerances.
Dimtolj	1	Controls vertical location of tolerance values rela- tive to nominal dimension: 0 = bottom; 1 = middle; 2 = top.
Dimtp	²	Indicates plus tolerance.
Dimtzin		Controls zero suppression in tolerance values: 0 = leave out zero feet and inches; 1 = include zero feet and inches; 2 = include zero feet; 3 = include zero inches; 4 = suppress leading zeros in decimal dimen- sions; 8 = suppress leading zeros in decimal dimen- sions; 12 = suppress leading and trailing zeros in decimal dimensions.
Dimension Variable	Default Setting	Description
Rounding
Dimazin		Controls zero suppression for angular dimensions: 0 = display all zeros; 1 = suppress leading zeros; 2 sup- press trailing zeros; 3 = suppress all zeros.
Dimrnd	²	Indicates a rounding value.
Dimzin		Controls zero suppression dimension text: 0 = leave out zero feet and inches; 1 = include zero feet and inches; 2 = include zero feet; 3 = include zero inches; 4 = suppress leading zeros in decimal dimensions; 8 = suppress leading zeros in decimal dimensions; 12 = suppress leading and trailing zeros in decimal dimensions.
Dimension Arrow & Text Control
Dimadec	“1	Controls the number of decimal places shown for angular dimension text: 1 = uses the value set by Dimdec dimension variable; 0 “8 = specifies the actual number of decimal places to be shown.
Dimatfit	3	Controls the way text and arrows are placed when there is not enough room to fit both within exten- sion lines: 0 = place both outside extension lines; 1 = move arrows first; 2 = move text first; 3 = move either text or arrows, whichever is best fit.
Dimaunit		Controls angle format for angular dimensions; set- tings are the same as for Aunits system variable.
Dimblk		Predefined or user-defined arrow block name. You can enter a user-defined block name or one of the following: _DOT, _DOTSMALL, _DOTBLANK, _ORI- GIN, _ORIGIN2, _OPEN, _OPEN90, _OPEN30, _CLOSED, _SMALL, _OBLIQUE, _BOXFILLED, _BOXBLANK, _CLOSEDBLANK, _DATUMFILLED, _DATUMBLANK, _INTEGRAL, ARCHTICK.
Dimblk1		Predefined or user-defined arrow block name for first end of dimension line used with Dimsah. See Dimblk for valid options.
Dimblk2		Predefined or user-defined arrow block name for second end of dimension line used with Dimsah. See Dimblk for valid options.
Dimdsep	. (period)	User-defined separator for decimals when dimen- sion units are set to decimal.
Dimfit	3	Controls location of text and arrows for extension lines, if space is not available for both: 0 = text and arrows placed outside; 1 = text has priority, arrows are placed outside extension lines; 2 = arrows have priority; 3 = AutoCAD chooses between text and arrows, based on best fit; 4 = a leader is drawn from dimension line to dimension text when space for text not available; 5 = no leader.
Dimfrac		Sets the fraction format for architectural and frac- tional formats: 0 = vertical; 1 = diagonal; 2 = not stacked .
Dimgap	¹ / ₁₆ ² or 0.09 ²	Controls distance between dimension text and dimension line.
Dimension Variable	Default Setting	Description
Dimjust		Controls horizontal dimension text position: 0 = centered between extension lines; 1 = next to first extension line; 2 = next to second extension line; 3 = above and aligned with the first extension line; 4 = above and aligned with second extension line.
Dimldrblk		Sets the arrow type for leaders : 0 = standard closed filled arrow; (period) = no arrow. See Dimblk for valid options.
Dimlunit	Off	Sets unit style for all dimension types except angu- lar: 1 = Scientific; 2 = Decimal; 3 = Engineering; 4 = Architectural; 5 = Fractional; 6 = WindowsDesktop.
Dimsah	Off	Allows use of two different arrowheads on a dimen- sion line. See Dimblk1 and Dimblk2.
Dimtfac	^1.0 ²	Controls scale factor for dimension tolerance text.
Dimtad		When on, places text above the dimension line.
Dimtih	On	When on, text inside extensions is horizontal.
Dimtix	Off	Forces text between extensions.
Dimtoh	On	When on, text outside extensions is horizontal.
Dimtvp value.		Controls
Dimtxsty	Standard	Controls text style for dimension text.
Dimunit	2	Controls unit style for all dimension style groups except angular. Settings are same as for Lunit sys- tem variable.
Dimension & Extension Line Control
Dimsd1	Off	When on, suppresses the first dimension line.
Dimsd2	Off	When on, suppresses the second dimension line.
Dimse1	Off	When on, suppresses the first extension line.
Dimse2	Off	When on, suppresses the second extension line.
Dimsoxd	Off	When on, suppresses dimension lines outside extension lines.
Dimtofl	Off	When on, forces a dimension line between exten- sion lines.
Alternate Dimension Options
Dimalt	Off	When on, alternate units selected are shown.
Dimaltd	2	Indicates alternate unit decimal places.
Dimaltf	25.4000	Indicates alternate unit scale factor.
Dimalttd	2	Indicates alternate unit tolerance decimal places.
Dimaltu	2	Indicates alternate unit style. See Lunits system variable for values.
Dimaltz		Controls the suppression of zeros for alternate dimension values.
Dimapost		Adds suffix to alternate dimension text.
Dimpost		Adds suffix to dimension text.
Colors and Line Weights
Dimclrd	0 or ByBlock	Controls color of dimension lines and arrows.
Dimclre	0 or ByBlock	Controls color of dimension extension lines.
Dimclrt	0 or ByBlock	Controls color of dimension text.
Dimlwd	ByBlock	Controls the line weight of dimension lines. Valid values are ByLayer, ByBlock, or integer representing 100th millimeter.
Dimlwe	ByBlock	Controls the line weight of extension lines. Valid values are ByLayer, ByBlock, or integer representing 100th millimeter.

Finally, for those of you who might want to write macros, scripts, or AutoLISP programs to control dimension styles, you'll learn about using two options of the Dimstyle command to set and recall dimension styles from the command line: “ Dimstyle S and “Dimstyle R .

If you want to change a setting through the command line instead of through the Dimension Style dialog box, you can enter the system variable name at the command prompt.

Storing Dimension Styles through the Command Line

After you have set the dimension variables as you like, you can save the settings by using the Dimstyle command. The Dimstyle/Save command records all the current dimension variable settings (except Dimassoc) with a name you specify. Follow these steps:

At the command prompt, enter “Dimstyle .
At the [Save/Restore/Status/Variables/Apply/?] <Save>: prompt, press .
When the Enter name for new dimension style or [?]: prompt appears, you can enter a question mark ( ? ) to get a listing of any dimension styles currently saved, or you can enter a name under which you want the current settings saved.

For example, suppose you change some of your dimension settings through dimension variables instead of through the Dimension Style dialog box, as shown in the following list:

Dimtsz 0.044

Dimtad On

Dimtih Off

Dimtoh Off

These settings are typical for an architectural style of dimensioning; you might save them under the name My Architectural, as you did in an exercise in Chapter 9. Then suppose you change other dimension settings for dimensions in another format ” surveyor 's dimensions on a site plan, for example. You might save them with the name Survey, again using the Save option of the Dimstyle command. When you want to return to the settings you used for your architectural drawing, use the Restore option of the Dimstyle command, described in the next section.

Restoring a Dimension Style from the Command Line

To restore a dimension style you've saved by using the Dimstyle Save option:

At the command prompt, enter “Dimstyle .
At the [Save/Restore/STatus/Variable/Apply/?] <Restore>: prompt, press .
At the following prompt

Enter dimension style name or [?] or <select dimension>:

you have three options: enter a question mark (?) to get a listing of saved dimension styles; enter the name of a style, such as Arch, if you know the name of the style you want; or use the cursor to select a dimension on the screen whose style you want to match.

Notes on Metric Dimensioning

The AutoCAD user community is worldwide, and many of you might be using the metric system in your work. As long as you are not mixing Imperial (feet and inches) and metric measurements, using the metric version of AutoCAD is fairly easy. In the Drawing Units dialog box (choose Format Units), set your measurement system to decimal, and set the Drawing Units For DesignCenter Blocks option to the appropriate metric option; then draw distances in millimeters or centimeters. At plot time, select the MM radio button (millimeters) under Paper Size and Paper Units in the Plot dialog box.

If your drawings are to be in both Imperial and metric measurements, you will be concerned with several settings, as follows :

Dimlfac Sets the scale factor for dimension values. The dimension value will be the measured distance in AutoCAD units times this scale factor. Set Dimlfac to 25.4 if you have drawn in inches but want to dimension in millimeters. The default is 1.00. If you want to scale dimension values from millimeters to inches, use a value of 0.03937.

Dimalt Turns the display of alternate dimensions on or off. Alternate dimensions are dimension text added to your drawing, in addition to the standard dimension text.

Dimaltf Sets the scale factor for alternate dimensions (that is, to metric from Imperial). The default is 25.4, which is the millimeter equivalent of 1 ² . If you are using metric ISO units, the default will be 0.03937, which is the inch equivalent of 1 mm.

Dimaltd Sets the number of decimal places displayed in the alternate dimensions.

Dimapost Adds asuffix to alternate dimensions, as in 4.5 mm.

Using the AutoCAD Metric Template

If you prefer, you can use the metric template drawing supplied by AutoCAD:

Choose File New. If you see the Select Template dialog box, go to step 2; otherwise skip to step 3.
Select the Acadiso.dwt file and click Open . You can also select ACADISO “ Named Plot Style.DWT if you want to use a named plot style.
In the Create New Drawing dialog box, click the Template button. Then select the filename Acadiso.dwt and click OK to open the template. You can also select ACADISO “ Named Plot Style.DWT if you want to use a named plot style.

These templates are set up for metric/ISO standard drawings. You can also use the Metric radio button in the Start From Scratch option of the Create New Drawing dialog box. When you choose Metric from the Create New Drawing dialog box, subsequent new files will be set to metric by default.

If the AutoCAD 2005 Startup dialog box does not appear when you open AutoCAD or if you don't see the Create New Drawing dialog box when you choose File New, you can turn these dialog boxes on by using the Startup option in the System tab of the Options dialog box. Choose Tools Options and then click the System tab in the Options dialog box. In the General Options group , select Show Startup Dialog Box from the Startup drop-down list.