Assembly3 ConstraintAxial

From FreeCAD Documentation

This documentation is not finished. Please help and contribute documentation.

GuiCommand model explains how commands should be documented. Browse Category:UnfinishedDocu to see more incomplete pages like this one. See Category:Command Reference for all commands.

See WikiPages to learn about editing the wiki pages, and go to Help FreeCAD to learn about other ways in which you can contribute.

Other languages:

Assembly3 ConstraintAxial

Menu location
Default shortcut
Introduced in version
See also


This tool builds a link between two or more objects of an assembly and matches their orientation. The selected elements of each object or more precisely their implicit coordinate systems (ICS) are used to position one object to another.

Assuming the first object is already locked in place by the Lock constraint then the following objects are moved to positions where the z-axes are collinear .

The offset of their origins on their common z-axis and the angle between their x-axes (and y-axes as well) are not defined. Related to the first object the following objects can still move along and spin around the z-axis. This is leaving 2 degrees of freedom (DOFs) for each link unconstrained.

The constraint accepts

- straight edges, which become collinear,
- planar faces, which are aligned using their surface normal axis,
- cylindrical faces, which are aligned using the axial direction.

Different types of geometry elements can be mixed.


  1. Place two or more objects into an assembly.
  2. Select one element of each object.
  3. Activate the Assembly3 ConstraintAxial command using:

Kinematic Equivalent

Used in kinematic context this constraint resembles a cylindrical joint.

In real life we cannot handle axes and so cylindrical faces are used to represent the linked axes.

Constrained objects before and after running the solver and then slid along the axis