5.1 Dimension styles.

A dimension style is a named set of settings that controls how every dimension in a drawing looks: the type and size of arrowheads, the extension and dimension lines, the text height and position, the units and precision, and how dimensions fit into tight spaces. Instead of formatting each dimension separately, the designer sets up a style once and applies it, so all dimensions in a drawing set look consistent and follow office and industry standards. Dimension styles can also be made annotative so that the same style prints at the correct size at different drawing scales. Example: a flour mill's office refurbishment drawings use a style named INT-50 with architectural ticks, 2.5 mm text and millimetre units with no decimals, so every plan and elevation dimension prints identically.

5.1.1 Parts of a dimension

Every linear dimension is made of the same parts, and the dimension style controls each of them. Understanding the parts makes it easier to choose the right settings. Example: a motor garage's workshop plan shows that the extension lines start 2 mm away from the wall so they do not touch the wall outline.

5.1.2 Dimension style settings

Dimension style settings are grouped into tabs in the Dimension Style Manager. Each tab controls one aspect of how dimensions appear. Example: a dental laboratory's joinery drawings use a style whose Primary Units tab shows millimetres with no decimals, while its Fit tab places text above the line when space is tight.

Lines

• Dimension line colour and line weight: Set by layer or a fixed thin weight so dimensions stay lighter than the drawing.
• Extend beyond ticks: How far the dimension line runs past architectural ticks, typically 1 to 2 mm.
• Baseline spacing: Distance between stacked dimension lines, usually 7 to 10 mm.
• Extension line offset from origin: Gap between the object and the start of the extension line.
• Fixed-length extension lines: Option to keep extension lines a set length for a tidy appearance.

Symbols and arrows

• Arrowhead type: Architectural ticks are standard for building and interior drawings, while closed arrows suit joinery and furniture details.
• Arrow size: Size of the arrowhead or tick at print scale, usually 2 to 3 mm.
• Centre marks: Type and size of marks placed on circles and arcs.
• Arc length symbol: Position of the symbol on arc-length dimensions.
• Jog angle: Angle of the jog on jogged radius dimensions.

Text

• Text style: The text style used for dimension text, set up separately in the text style settings.
• Text height: Printed height of the dimension text, commonly 2.5 mm.
• Text placement: Vertical position above or centred on the line, and horizontal position.
• Text alignment: Aligned with the dimension line or always horizontal.
• Offset from dimension line: Gap between the text and the line.

Fit

• Fit options: What moves outside the extension lines when space is tight: text, arrows or both.
• Text placement when moved: Whether text moves beside the line, above it with a leader, or above it without a leader.
• Scale for dimension features: Overall scale factor or annotative setting that controls printed size.
• Draw dimension line between extension lines: Keeps a dimension line even when text is outside.

Primary units

• Unit format: Decimal for metric drawings.
• Precision: Number of decimal places, usually 0 for millimetre drawings.
• Measurement scale factor: Multiplies measured values, used when a drawing is not at full size.
• Zero suppression: Removes leading or trailing zeros.
• Prefix and suffix: Adds text such as "mm" or "R" automatically.

Alternate units and tolerances

• Alternate units: Shows a second unit, such as inches beside millimetres, for imported products.
• Tolerance method: Shows permitted variation, such as 600 ±2, for manufactured joinery.
• Tolerance precision: Decimal places of the tolerance values.
• Upper and lower values: The allowed variation above and below the dimension.
• Use in interior work: Tolerances are mainly used in joinery and shop drawings rather than general plans.

5.1.3 Dimension styles and drawing scale

Dimension text and arrows must print at the same size whatever the drawing scale. This is achieved either with an overall scale factor or with annotative styles. Example: an estate agent's show house drawings at 1:50 and 1:20 both print dimension text 2.5 mm high because the style is annotative.

Methods of scaling dimension styles

Worked example: overall scale factor for dimension text

Model text height = printed text height × scale factor

A tea room's plan is printed at 1:50 and dimension text must print 2.5 mm high.

Model text height = 2.5 × 50

Model text height = 125 mm in model space

Typical interior dimension style values

5.1.4 Creating and managing dimension styles

Dimension styles are created in the Dimension Style Manager and saved in the office template so they are available in every new drawing. Child styles and overrides allow variations without creating many separate styles. Example: a vocational centre's drafting lecturer sets up two styles in the class template, one for plans and one for details, so all students' drawings look consistent.

Steps for creating a dimension style

1. Open the Dimension Style Manager: Type D or DIMSTYLE and press Enter.
2. Start a new style: Click New, name the style clearly, such as INT-PLAN, and choose a style to start from.
3. Set annotative if required: Tick Annotative so the style scales automatically.
4. Set lines: Adjust extension line offset, extension beyond the dimension line and baseline spacing.
5. Set symbols and arrows: Choose architectural ticks and set the size.
6. Set text: Select the text style, set the height and choose placement above the line.
7. Set fit: Choose how text and arrows move when space is tight and set the scale method.
8. Set primary units: Choose decimal millimetres with zero precision and suppress trailing zeros.
9. Save and set current: Click OK, then Set Current, and test the style on a sample dimension.

Managing dimension styles

• Child styles: Variations for one dimension type, such as radius dimensions with arrows inside a style that uses ticks.
• Style overrides: Temporary changes to one dimension without changing the style, used sparingly.
• Updating dimensions: Changing a style updates every dimension that uses it.
• Comparing styles: The Compare button shows differences between two styles.
• Transferring styles: Styles are copied between drawings using DesignCenter or by including them in templates.
• Purging unused styles: Unused styles are removed before issuing drawings.

Worked example: dimension style for a scale not yet set up

Required scale factor = 1 ÷ drawing scale ratio

A shopping arcade's shopfront elevation is to be printed at 1:25, and the office only has a 1:50 style with factor 50.

Required scale factor = 1 ÷ (1/25) = 25

Change in size from the 1:50 style = 25 ÷ 50 = 0.5

A copy of the 1:50 style is made with scale factor 25, so text and arrows print at the same size as on 1:50 drawings.