Part JoinCutout

From FreeCAD Documentation

Part JoinCutout

Menu location
Part → Join → Cutout for Object
Default shortcut
Introduced in version
See also
Part JoinConnect, Part JoinEmbed, Part Boolean, Part Thickness


The Part JoinCutout tool creates a cutout in a walled object (e.g., a pipe) to fit another walled object.


  1. Select the base object first, then the object to define the cutout.
    The order of selection is important. It is enough to select one sub-shape of each object (e.g., faces).
  2. Invoke the Part JoinCutout command several ways:
    • Pressing on the Part JoinCutout button in the Part toolbar
    • Using the Part → Join → Cutout for Object entry in the Part menu

A Part JoinFeature object is created, with Mode set to 'Cutout'. Original objects are hidden, and the result of cutting is shown in 3D view.



  • DataBase: Reference to base object (the one to make the cutout in). The object should be a single solid.
  • DataTool: Reference to tool object (the object that is to fit into the cutout). The object can be a single solid, or a valid compound of solids.
  • DataMode: The mode of operation, equals 'Cutout' (Changing that will transform the tool into another Part_JoinXXX). The value of 'bypass' can be used to temporarily disable the long computations (a compound of Base and Tool will be created, which is a fast operation).
  • DataRefine: Sets whether to apply Refine operation or not, to the final shape. The default value is determined by a 'Automatically refine shape after boolean operation' checkbox in PartDesign preferences. When Mode property is 'bypass', Refine is ignored (never applied).


  1. Create a pipe by applying thickness to a cylinder:
  2. Create another, smaller diameter pipe, and place it so that it pierces the wall of the first pipe:
  3. Select the first pipe, then the second pipe (order of selection is important), and click the 'Cutout for object' option from the Join tools dropdown toolbar button.


The algorithms behind Join tools are quite simple, and understanding them is important to use the tools correctly.

1. Base object is boolean-cut with Tool object. The resulting shape is a set (compound) of non-intersecting solids (typically, two).

2. The resulting compound is filtered: only the largest solid is kept.

3. If Refine property is true, the resulting shape is refined.


  • If after step 1, the object remains in one piece, the result of Cutout will be equivalent to boolean cut of Base with Tool.
  • Now, the tool will produce unexpected result, if a compound is supplied as Base. This may be changed in the future.
  • Because the largest piece is determined by comparing volumes of pieces, the tool can only work with solids. This may be changed in the future.


The Join tools can by used in macros and from the python console by using the following function:

JoinFeatures.makePartJoinFeature(name = 'Cutout', mode = 'Cutout')
  • Creates an empty Cutout feature (or other Join feature, depending on mode passed). The properties Base and Tool must be assigned explicitly, afterwards.
  • Returns the newly created object.


import JoinFeatures
j = JoinFeatures.makePartJoinFeature(name = 'Cutout', mode = 'Cutout' )
j.Base = FreeCADGui.Selection.getSelection()[0]
j.Tool = FreeCADGui.Selection.getSelection()[1]

The tool itself is implemented in Python, see /Mod/Part/ (Github link) under where FreeCAD is installed.