Select Overhangs selects the downward-facing areas of a model that hang too far out over the layer below when you print it layer by layer. These areas usually need supports, or a different orientation of the part.
You find the tool in Select › Select Overhangs.
How It Decides
The tool does not ask for an angle. It thinks in print layers: a triangle facing down is an overhang if, over the height of one Layer Step, the surface moves sideways by more than Max Overhang Distance. With both values equal, as by default, this is the familiar 45° rule; a larger Max Overhang Distance allows flatter overhangs and selects less.
- The lowest layer (up to one Layer Step above the lowest point) is never selected: it lies on the build plate.
- Small overhang areas that are not taller than one layer and narrower than Max Overhang Distance are left out.
Select Overhangs: Settings and Controls
- Select one mesh. The tool works only when exactly one mesh is selected.
- Go to Select › Select Overhangs. An arrow shows the print direction on the model.
- Set the Direction: the direction from the build plate up, as the part will be printed.
- Set Layer Step and Max Overhang Distance and click Apply (or press Enter). The overhangs turn red.
| Setting | What it does | Default |
|---|---|---|
| Direction | Three components of the up direction. To X, To Y and To Z set it along an axis, To Camera points it at the camera. You can also drag the arrow in the viewport. | 0, 0, 1 (up along Z) |
| Layer Step | The height of one layer. | 1 mm (0.01 to 1000) |
| Max Overhang Distance | How far the surface may move sideways within one layer before it counts as an overhang. | 1 mm (0.01 to 1000) |
| Smooth Out Overhangs | Removes small gaps and artifacts from the found areas. | On |
The result is added to the triangles that were already selected, so clear the selection first (Ctrl+X, Cmd+X on macOS) if you run the tool again with other settings.
Select Overhangs: Example
Here the Direction was set with To Camera, and the overhangs relative to this direction are shown in red.
What to Do Next
- Turn the part so that fewer areas hang over, for example with Transform Object, and run the tool again.
- Plan supports for the remaining areas in your slicer, or prepare the slices in MeshInspector: see How to Slice 3D Meshes for 3D Printing.
- Before printing, also check the model with Select Self Intersections and Select Degeneracies.
