Part Mirror

From FreeCAD Documentation

Part Mirror

Menu location
Part → Mirroring...
Default shortcut
Introduced in version
See also


Part Mirror creates a new object (image) which is a reflection of the original object (source). The image object is created behind a mirror plane. The mirror plane may be standard plane (XY, YZ, or XZ), any plane parallel to a standard plane, or (introduced in version 1.0) any arbitrary plane by using a reference object.

An example:


After mirrored through YZ plane


  1. Optionally select one or more source objects.
  2. There are several ways to invoke the command:
    • Press the Mirroring... button.
    • Select the Part → Mirroring... option from the menu.
  3. If you have not yet selected objects or want to change the selection: pick one or more objects from the Shapes list.
  4. Do one of the following:
  5. Press the OK button.
  6. For each source object a separate Part Mirror object is created.

When the select button label says Selecting you are in reference selection mode and there is a selection gate in effect, which disallows the selection of unsupported reference objects. Click the button to toggle the selection gate off, the button label then changes to Select reference.

The mirror plane is defined by a DataNormal (direction) and a DataBase (position). When the DataMirror Plane property contains a reference object these properties are made read-only as they are then computed based on that object. The plane is infinite even if the reference object is not.

A reference object can be a planar face, such as the face of a Part Box, a circular edge, a Datum Plane, an origin plane of a Std Part container, or any object with a single planar face or single circular edge. There is also support for Links. Note, however, that B-spline surfaces, such as ruled surfaces or loft faces are not supported.


If a standard plane instead of a reference object is selected, the Base point boxes can be used to move it. Only one of the X, Y, or Z boxes is effective for a given standard plane.

Standard plane Base point box Effect
XY Z Move mirror plane along Z axis
XY X, Y No effect
XZ Y Move mirror plane along Y axis
XZ X, Z No effect
YZ X Move mirror plane along X axis
YZ Y, Z No effect


  • App Link objects linked to the appropriate object types and App Part containers with the appropriate visible objects inside can also be used as source objects. introduced in version 0.20
  • After selecting a standard mirror plane, the DataNormal and DataBase of the Part Mirror object can be changed to any value. So that even without a reference object you are not restricted to the standard planes.