Radial Diameter Dimension

Parent page: PCB Dialogs

The Radial Diameter Dimension dialog.


This dialog allows the designer to specify the properties of a Radial Diameter Dimension object. A radial diameter dimension is a group design object. It allows for the dimensioning of an arc or circle with respect to the diameter, rather than the radius. The dimension can be placed either internally or externally, in relation to the circumference of the arc/circle.

For information on how a placed radial diameter dimension object can be modified graphically, directly in the workspace, see Graphical Editing.


The Radial Diameter Dimension dialog can be accessed during placement by pressing the Tab key.

After placement, the dialog can be accessed in one of the following ways:

  • Double-clicking on the placed radial diameter dimension object.
  • Placing the cursor over the radial diameter dimension object, right-clicking and choosing Properties from the context menu.


  • Text Width - the current dimension text stroke width (the "thickness" of the lines used to produce the lettering).
  • Line Width - the current arrow line width (the "thickness" of the lines used to produce the arrows).
  • Text Height - the current height of the dimension text characters. The character width used to display or print the text is automatically proportioned to this height. A minimum height of 36mil (0.9mm) will allow the string to be legibly photoplotted.
  • Text Gap - the current gap between the dimension text and the non-arrow end of the arrow line.
  • Arrow Size - the current arrowhead size. The size is measured as the distance between the arrow tip and the end of the arrow 'legs'.
  • Arrow Length - the current length of the arrow to which the dimension text is not associated. Note that the value entered into this field is applied only when the Arrow Position is set to Outside.
Quickly change the units of measurement currently used in the dialog between metric (mm) and imperial (mil) using the Ctrl+Q shortcut. This affects the dialog only and does not change the actual measurement unit employed for the board, as determined by the  and  buttons in the Home | Grids and Units area of the main menus.


  • Layer - the layer the dimension is currently assigned to. Dimensions can be assigned to any available layer, click on the list to view and select a different layer, from all those currently defined for the board.
  • Format - the current setting for the format of the dimension text. Use the associated drop-down to change the format as required. The options listed will depend on the chosen Unit and present based on the actual value for the current dimension. In generic terms, the available options are:
    • None - no dimension text is displayed.
    • Value Only - no units are displayed, only the dimension value (eg. ø600.00).
    • Value and Unit - units are displayed after the dimension value (eg. ø600.00mil).
    • Value and Bracketed Unit - units are displayed in brackets after the dimension value (eg. ø600.00(mil)).
For all formats other than None, the fixed prefix of ø is also displayed.
  • Text Position - the current position of the dimension text. Use the associated drop-down list to choose one of the following options:
    • Aligned - the dimension text will be aligned with the angle of the dimension line.
    • Unidirectional - the dimension text will remain horizontal, irrespective of the dimension alignment angle.
    • Manual - the dimension text will be available for manual placement by the user.
  • Unit - the current unit that is selected for the calculation and display of the dimension value. Choose either Mils, Millimeters, Inches, Centimeters, or Automatic.
The Automatic setting follows the actual measurement unit employed for the board, as determined by the  and  buttons in the Home | Grids and Units area of the main menus.
  • Arrow Position - the current position of the dimension arrows. The available options are:
    • Inside - the arrows will be positioned inside the arc/circle (pointing outwards).
    • Outside - the arrows will be positioned outside the arc/circle (pointing inwards).
  • Precision - the current setting for the number of decimal places to the right of the decimal point that the dimension will be displayed to. The maximum number of decimal places is 6.
  • Angular Step - the current angular step setting for the dimension. This is the rotation step used when placing the arrow portion of the dimension. Moving the arrow around the circle or arc during placement of the dimension, the number and position of possible places to anchor the dimension are determined by this angular step value.
  • Prefix - the prefix to the dimension value. This field is fixed with the character ø.
  • Locked - enable this option to protect the dimension from being edited graphically.
An object that has its Locked property enabled cannot be selected or graphically edited. Double click on the locked object directly and disable the Locked property, to graphically edit the object.
  • Suffix - the current suffix to the dimension value.
  • Sample - this field presents a sample of how the dimension text will appear, in accordance with specified Format, the fixed ø Prefix and any defined Suffix.

Select TrueType Font

  • Font Name - use this field to choose the required TrueType font. The drop-down list is populated with TrueType and OpenType (a superset of TrueType) fonts found in the \Windows\Fonts folder. Note, the list will only include entries for detected (and uniquely named) root fonts. For example, Arial and Arial Black will be listed but Arial Bold, Arial Bold Italic, etc will not. Use the Bold and Italic options to add emphasis to the text.
  • Bold - enable this option to make the dimension text bold.
  • Italic - enable this option to make the dimension text italic.


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