Assembly3 ConstraintAngle

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Assembly3 ConstraintAngle

Menu location
Default shortcut
Introduced in version
See also


This tool builds a link between two 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.

The angle between two elements i.e. the angle between their z-axes is fixed.

The offset of their origins in x-, y- and z-direction and the angles between the x-, and y-axes are not defined. Related to the first object the following object can still move along the x-, y- and z-axis and spin around both z-axes. This is leaving 5 degrees of freedom (DOFs) for each link unconstrained.

The constraint accepts straight edges and planar faces.


  1. Place two or more objects into an assembly.
  2. Select one straight edge element or one planar face element of each object.
  3. Press the Create "Angle" Constraint button.
  4. Optionally change the value of the DataAngle property.


2D: This constraint seems to be the only way to control an angle in a skeleton sketch (2D kinematic assembly); Prove me wrong, PLEASE!

  • Its DataAngle (Angle) property allows any positive value, but 0° and 180° exactly are puzzling the solver.
  • It flips direction if angles greater than 180° are used and as a result 135° and 225° give the same positions for the involved elements.
It is useless if you want to simulate a full rotation and so ruins the principle of using a skeleton sketch for a lot of kinematic tasks such as driving a piston by a rotating crank coupled with a con-rod.