Sketcher ConstrainBlock

From FreeCAD Documentation

Sketcher ConstrainBlock

Menu location
Sketch → Sketcher constraints → Constrain block
Default shortcut
Introduced in version
See also
Sketcher ConstrainLock


The Sketcher ConstrainBlock tool blocks edges in place with a single constraint. It is mainly intended for B-splines, which can be difficult to fully constrain otherwise.

The block constraint only affects the freely movable parts of an edge. Blocked edges can have other constraints, and applying additional constraints to a blocked edge can modify it.


See also: Drawing aids.

Continue mode

  1. Make sure there is no selection.
  2. There are several ways to invoke the tool:
    • Press the Constrain block button.
    • Select the Sketch → Sketcher constraints → Constrain block option from the menu.
    • introduced in version 1.0: Right-click in the 3D view and select the Constrain → Constrain block option from the context menu.
    • Use the keyboard shortcut: K then B.
  3. The cursor changes to a cross with the tool icon.
  4. Select a single edge.
  5. A constraint is added.
  6. Optionally keep creating constraints.
  7. To finish, right-click or press Esc, or start another geometry or constraint creation tool.

Run-once mode

  1. Select one or more edges.
  2. Invoke the tool as explained above, or with the following additional option:
  3. Depending on the selection one or more constraints are added.


Sketch.addConstraint(Sketcher.Constraint('Block', Edge))

The Sketcher scripting page explains the values which can be used for Edge and contains further examples on how to create constraints from Python scripts.