Altium NEXUS Documentation


Created: June 10, 2016 | Updated: April 11, 2017

Parent page: CAMtastic Commands

The following pre-packaged resource, derived from this base command, is available:

Applied Parameters: CommandMode=CAM


This command is used to place circle objects on the current document. The circle is drawn using two points - tangent points that lie on two distinct reference lines - and a radius.


This command is accessed from the CAMtastic Editor by choosing the Place » Circle » Tangent, Tangent, Radius command from the main menus.


After launching the command, you will enter circle placement mode. Placement is made by performing the following sequence of actions:

  1. Position the cursor over the first reference line and click.
  2. Position the cursor over the second reference line and click again.
  3. The Enter Value dialog will now appear, prompting you to enter a value for the radius of the circle. After entering the radius required and clicking OK, the circle will be drawn between the two reference lines at a position that obeys the radius definition and results in the lines both remaining tangential to the circle.
  4. Continue placing further circles or right-click, or press Esc, to exit circle placement mode.


  1. A circle can only be drawn between two reference lines if those lines, when extrapolated, would intersect at a common point in the workspace (i.e. possess a common vertex).
  2. The radius entered will use the current units for the workspace - either inches or millimeters. Units can be changed either from the CAMtastic panel, or from the CAM Editor - Drawing Modes page of the Preferences dialog.
  3. Care should be taken when specifying the value for the radius. Remember that the circle will be drawn to satisfy the radius, whilst maintaining tangent points in both reference lines. If the radius specified is too small, the circle may not be visible, as the common vertex for the lines might be located at some distance away. If the radius is too large, the circle may appear floating, unconnected to the reference lines, because the tangent points lie at an extrapolated distance along the path of the lines.
  4. If polylines are to be used for drawing an circle, only adjacent straight lines from the same polyline are eligible tangents, otherwise you must explode the polyline before using this command.
  5. Circles will be drawn using the current DCode. Set the required DCode in the DCode field on the CAMtastic panel.
  6. Circles will be drawn on the current layer. The current layer is displayed on the CAMtastic panel at the top of the layers list. Double-clicking on any layer in the layers list will cause it to become the current layer.


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