Making Circles, Arcs or Ellipses Concentric

The Concentric tool in the Constraint toolbar enables you to make selected circles, arcs or ellipses concentric to another circle, arc or ellipse.

First, select one or more circles (or arcs/ellipses).
Then, select a circle, arc or ellipse that will define the position of the concentric circles/arcs/ellipses.
Finally, select the Concentric tool.

If none of the entities are restricted by pre-existing constraints, the entities that are selected first move to be concentric with the entity that is selected last.

If entities are restricted by pre-existing constraints, whenever possible, the independent entities will move to be concentric with the constrained entity.

Note: If the original circle / arc / ellipse is not in the current sketch, you must add it to the sketch as a reference entity.

Demo: Press the button below to view a short movie demonstrating the function:

Make circles/arcs/ellipses concentric to a selected circle/arc/ellipse

Select the Add Constraints button from the Sketcher toolbar.

The cursor will be a pointer-and-grid symbol.

Click one or more circles/arcs/ellipses that you wish to make concentric to another circle/arc/ellipse.

In the example above, two circles are selected. Both these circles will be concentric to the circle/arc selected last (in step 3).

Click the circle/arc/ellipse to which the entities selected in step 2 will be concentric.

Click the Concentric tool .

The entities selected first (in step 2) move to be concentric with the entity selected last (in step 3).

In the example above, none of the entities were previously constrained. If entities are already constrained, whenever possible, the independent entities will move to be concentric with the constrained entity.

Notes:

You can also first pick the entities to constrain (while in Select mode), then select the Add Constraints option, then choose the desired constraint.
Edit functions are restricted by pre-existing constraints. An entity will not be edited if underlying constraints do not permit. If required, you can break an entity's constraints to make it independent of all other entities.