Working with a Leader Dimension Object on a PCB in Altium Designer

Parent page: PCB Objects

Placed leader dimensions

Summary

A leader dimension is a group design object. It allows for the labeling of an object, point or area. The label text can be encapsulated in a circle, a square, or not at all, while the pointer can be an arrow or a dot.

Availability

Leader dimension objects are available for placement in the PCB editor only. Use one of the following methods to place a leader dimension:

• Choose Place » Dimension » Leader from the main menus.
• Click the Leader Dimension button () in the drop-down on the Active Bar located at the top of the workspace. (Click and hold an Active Bar button to access other related commands. Once a command has been used, it will become the topmost item on that section of the Active Bar).
• Click the  button on the Place Dimension drop-down  () of the Utilities toolbar.
• Right-click in the workspace then choose the Place » Dimension » Leader command from the context menu.

Placement

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 then click or press Enter to anchor the dimension start point (the location of the arrowhead or dot).
2. Move the cursor then click or press Enter to anchor a series of vertex points that define the shape of the leader.
3. After placing the final required vertex point, right-click or press Esc to effect placement of the text label and exit placement mode.

Additional actions that can be performed during placement are:

• Press the Tab key to pause the placement and access the Leader mode of the Properties panel from where its properties can be changed on-the-fly. Click the workspace pause button overlay ( ) to resume placement.

• Press the + and - keys (on the numeric keypad) to cycle forward and backward through all visible layers in the design to change placement layer quickly. Alternatively, use the Ctrl+Mouse Wheel shortcut to cycle through the available layers.
• Press Spacebar to toggle the dimensioning direction between horizontal and vertical.

Graphical Editing

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

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

A placed Leader Dimension

• Click and drag A to move the start point of the dimension (i.e. the position of the arrowhead).
• Click and drag B to move the end point of the dimension (i.e. the position of the text label).
• Click and drag intermediate handles to change the shape of the leader.

If the leader 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 then drag to reposition it. While dragging, the leader dimension can be rotated or mirrored:

• Press the Spacebar to rotate the leader dimension counterclockwise 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 leader dimension along the X-axis or Y-axis.

The following methods of non-graphical editing are available:

Via the Properties Panel

Properties page: Leader Dimension Properties

The properties of a Leader Dimension can be edited in the PCB editor's Properties panel, which allows editing of all item(s) currently selected in the workspace.

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

To access the properties of a placed Leader Dimension:

• Double-click on the Leader Dimension.
• Right-click on the Leader Dimension then select Properties from the context menu.
• If the Properties panel is already active, click once on the Leader Dimension to select it.

Via the PCB List Panel

Panel page: PCB List, PCB Filter

The PCB List panel allows you 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 you to target and edit multiple design objects with greater accuracy and efficiency.

Tips

1. A leader dimension object can be moved in the following ways:
   • Select both the dimension object and the object that is being dimensioned: the whole can be dragged to a new location as required.
   • Select the object that is being dimensioned only: the dimension will follow the object. The segment of the leader dimension (between the arrow/dot and the first defined elbow) will expand/contract to keep the relationship between the dimension and the object being dimensioned.
   • Select 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. When the reference to which a dimension object is attached is deleted, a dialog will open asking whether the dimension should also be deleted. If the dimension is not deleted, it remains in the workspace but non-referenced.
3. Leader 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.