Working with an Ordinate Dimension Object on a PCB in Altium Designer

Parent page: PCB Objects

A placed Ordinate Dimension

Summary

An ordinate dimension is a group design object. It allows for the dimensioning of a linear distance of a collection of references, relative to a single base reference. The first point chosen is the 'base'. All subsequent points are relative to this first point. The dimension value in each case is, therefore, the distance between each reference point and the 'base' measured in the default units. The references may be objects (tracks, arcs, pads, vias, text, fills, polygons, or components) or points in free space.

Availability

Ordinate 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 » Ordinate from the main menus.
• Locate and use the Ordinate command () on 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 » Ordinate 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 (this is the first reference object or 'base').
2. Move the cursor to the next required object then click or press Enter to anchor the dimension end point (this is the second reference object).
3. Move the cursor to subsequent reference objects then click or press Enter. When all desired objects have been selected, right-click or press Esc.
4. The text can now be initially positioned. Click or press Enter when the text is in the desired position to complete placement 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 to change placement layer quickly. Alternatively, use the Ctrl+Wheelroll 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 ordinate dimension object directly in the workspace and graphically change properties such as the position of its text and its reference points.

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

A selected Ordinate Dimension

• Click & drag handle A to move the dimension text.
• Click & drag the handles at B to move that reference individually with respect to the base.

1. A dimension object can be moved in the following ways:
   1. Selecting both the dimension object and the objects that are being dimensioned. The whole can be dragged to a new location as required.
   2. Selecting an object that is being dimensioned only. The dimension text will follow the object in its alignment plane only. The dimension extensions 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 objects it is dimensioning.
2. The dimension's value automatically updates as its start or end points are moved. Likewise, if the position of an object that a reference point of the dimension is anchored to is changed, the dimension will update and expand/contract to reflect this.
3. If the dimension object is totally non-referenced (i.e. it is not attached to any reference design objects), click anywhere on it away from editing handles then drag to reposition it. While dragging, the dimension can be rotated or mirrored:
   1. Press the Spacebar to rotate the 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.
   2. Press the X or Y keys to mirror the dimension along the X-axis or Y-axis.

Non-Graphical Editing

The following methods of non-graphical editing are available:

Editing Via the Properties Panel

Properties page: Ordinate Dimension Properties

The properties of an Ordinate 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 Ordinate Dimension:

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

Editing 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. When the reference or references to which a dimension object is attached are 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 is non-referenced.
2. Ordinate 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.