Altium Designer Documentation

PCB_Obj-RadialDiameterDimensionRadial Diameter Dimension_AD

Created: August 30, 2017 | Updated: August 30, 2017
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Parent page: PCB Objects

A placed Radial Diameter dimension.


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.


Radial Diameter dimension objects are available for placement in the PCB Editor only. Use one of the following methods to access a placement command:

  • Choose Place » Dimension » Radial Diameter from the main menus.
  • Click the  button on the Place Dimension drop-down () of the Utilities toolbar.


After launching the command, the cursor will change to a cross-hair and you will enter dimension placement mode. Placement is made by performing the following sequence of actions:

  1. Position the cursor and click or press Enter to anchor the dimension to the desired arc or circle.
  2. Move the dimension's arrow pointer to the desired location around the arc or circle. The arrow can be placed either inside or outside and movement is in accordance with the Angular Step value in the Radial Diameter Dimension dialog. When the required position has been attained, click or press Enter to lock the arrow in place.
  3. The text can now be initially positioned in relation to the tail of the arrow pointer. Move the text into the required position and click or press Enter to complete placement.
  4. Continue placing further radial diameter dimensions, or right-click or press Esc to exit placement mode.

Additional actions that can be performed during placement are:

  • Press the + and - keys (on the numeric keypad) to cycle forward and backward through all visible layers in the design respectively – to change placement layer quickly.
  • Press the Tab key to access an associated properties dialog, from where properties for the dimension can be changed on-the-fly.

While attributes can be modified during placement (Tab to bring up associated properties dialog), bear in mind that these will become the default settings for further placement unless the Permanent option on the PCB Editor – Defaults page of the Preferences dialog is enabled. When this option is enabled, changes made will affect only the object being placed and subsequent objects placed during the same placement session.

Graphical Editing

This method of editing allows you to select a placed radial diameter dimension object directly in the workspace and change properties such as the position of its text and its reference point, graphically.

When a radial diameter dimension object is selected, the following editing handles are available:

A selected Radial Diameter Dimension.

  • Click & drag A to adjust the leader position, relative to the 'tail' of the arrow pointer.
  • Click & drag B to adjust the position of the arrow pointer around the circumference of the circle or arc or change the length of the arrow leader line.
  • Click & drag C to move the start point of the dimension.

Handle C allows you to redefine the reference – once the dimension is detached from a reference object it becomes non-referenced and can be moved for attachment to a different reference object.

If the dimension text is placed within the circumference of the arc or circle, only two of the three editing handles will be available for use – A and C. Editing handle A will assume the additional role of editing handle B.

If the radial diameter dimension object is totally non-referenced (i.e. it is not attached to a reference design object) click anywhere on it – away from editing handles – and drag to reposition it. While dragging, the radial diameter dimension can be rotated or mirrored:

  • Press the Spacebar to rotate the radial diameter dimension anti-clockwise or Shift+Spacebar for clockwise rotation. Rotation is in accordance with the value for the Rotation Step, defined on the PCB Editor – General page of the Preferences dialog.
  • Press the X or Y keys to mirror the radial diameter dimension along the X-axis or Y-axis respectively.

If attempting to graphically modify an object that has its Locked property enabled, a dialog will appear asking for confirmation to proceed with the edit. If the Protect Locked Objects option is enabled on the PCB Editor – General page of the Preferences dialog, and the Locked option for that design object is enabled as well, then that object cannot be selected or graphically edited. Double click on the locked object directly and disable the Locked property or disable the Protect Locked Objects option, to graphically edit the object.

Non-Graphical Editing...

The following methods of non-graphical editing are available:

Via an Associated Properties Dialog

Dialog page: Radial Diameter Dimension

This method of editing uses the following dialog to modify the properties of a radial diameter dimension object.

The Radial Diameter Dimension dialog.

The Radial Diameter Dimension dialog can be accessed prior to entering placement mode, from the PCB Editor – Defaults page of the Preferences dialog. This allows the default properties for the radial diameter dimension object to be changed, which will be applied when placing subsequent radial diameter dimensions.

During placement, the dialog can be accessed by pressing the Tab key.

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

  • Double-clicking on a placed radial diameter dimension object.
  • Placing the cursor over a radial diameter dimension object, right-clicking and choosing Properties from the context menu.
  • Using the Edit » Change command and clicking once over a placed radial diameter dimension object.

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 Measurement Unit setting in the Board Options dialog (Design » Board Options).

Via the PCB Inspector Panel

Panel page: PCB Inspector, PCB Filter

The PCB Inspector panel enables the designer to interrogate and edit the properties of one or more design objects in the active document. Used in conjunction with appropriate filtering - by using the PCB Filter panel, or the Find Similar Objects dialog - the panel can be used to make changes to multiple objects of the same kind, from one convenient location.

Via the PCB List Panel

Panel page: PCB List, PCB Filter

The PCB List panel allows the designer to display design objects from one or more documents in tabular format, enabling quick inspection and modification of object attributes. Used in conjunction with appropriate filtering - by using the PCB Filter panel, or the Find Similar Objects dialog - it enables the display of just those objects falling under the scope of the active filter – allowing the designer to target and edit multiple design objects with greater accuracy and efficiency.


  1. A radial diameter dimension object can be moved in the following ways:
    1. Selecting both the dimension object and the object that is being dimensioned. The whole can be dragged to a new location as required.
    2. Selecting the object that is being dimensioned only. The dimension text will follow the object in its alignment plane only. The dimension pointer and tail will expand/contract to keep the relationship between dimension and object being dimensioned.
    3. Selecting the dimension object only. It is important to note that the dimension cannot be moved on its own if it is referenced by a design object. To move the dimension only, it must first be detached from the object it is dimensioning.
  2. The dimension's value automatically updates as the radius of the reference arc or circle changes.
  3. When the reference arc or circle to which a radial diameter dimension object is attached is deleted, a dialog will appear, asking whether the dimension should also be deleted. If the dimension is not deleted, it remains in the workspace, but non-referenced.
  4. Radial diameter dimensions are group objects consisting of text and track segments. They can be converted to their set of primitive objects by choosing Tools » Convert » Explode Dimension to Free Primitives from the main menus. Once exploded, a dimension object can no longer be manipulated as a group object.


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