Linear Diameter Dimension

Parent page: Dimension

Placed Linear Diameter Dimensions

Summary

A linear 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.

Availability

Linear Diameter dimension objects are available for placement in the PCB Editor only by clicking Home | Dimension | 

then selecting Linear Diameter from the drop-down list.

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 to the desired arc or circle. The position of the dimension is determined by the alignment angle for the dimension.
2. Move the dimension text to the desired position (either internal or external) then click or press Enter to complete placement.
3. Continue placing further linear 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 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.
• 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 linear diameter dimension object directly in the workspace and change properties such as the position of its text and its reference points graphically.

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

A selected Linear Diameter Dimension

• Click & drag A or B to adjust the dimension text position parallel to the extensions.
• Click & drag C or D to detach the dimension from the reference object.

If the linear 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 linear diameter dimension can be rotated (Spacebar/Shift+Spacebar).

Non-Graphical Editing

The following methods of non-graphical editing are available:

Via an Associated Properties Dialog

Dialog page: Linear Diameter Dimension

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

The Linear Diameter Dimension dialog

The Linear 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-click on the placed linear diameter dimension object.
• Place the cursor over the linear diameter dimension object, right-click then choose Properties from the context menu.

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.

Via the PCB Inspector Panel

Panel page: PCB Inspector

The PCB Inspector panel enables you to interrogate and edit the properties of one or more design objects in the active document. Used in conjunction with appropriate filtering, the panel can be used to make changes to multiple objects of the same kind, from one convenient location.

Notes

1. A linear 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 extensions will expand/contract to keep the relationship between dimension and object 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 diameter of the reference arc or circle changes.
3. When the reference arc or circle to which a linear diameter 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.