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 access a placement command:

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

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 and click or press Enter to anchor the dimension start point (this is the location of the arrowhead or dot).
2. Move the cursor and 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 + 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.

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, graphically.

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

A placed Leader Dimension.

• Click & drag A to move the start point of the dimension (i.e. the position of the arrowhead).
• Click & drag B to move the end point of the dimension (i.e. the position of the text label).
• Click & 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 – and drag to reposition it. While dragging, the leader dimension can be rotated or mirrored:

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

Non-Graphical Editing...

The following methods of non-graphical editing are available:

Via an Associated Properties Dialog

Dialog page: Leader Dimension

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

The Leader Dimension dialog.

The Leader 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 leader dimension object to be changed, which will be applied when placing subsequent leader 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 leader dimension object.
• Placing the cursor over a leader dimension object, right-clicking and choosing Properties from the context menu.
• Using the Edit » Change command and clicking once over a placed leader dimension object.

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.

Tips

1. A leader 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 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 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. When the reference to which a 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.
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.