Check an assembly for clashes and motion

Two checks run on the parts as they are placed: Clash looks for overlapping material right now, and the motion check moves one joint through its range and looks for overlaps along the way.

Check for interference

1. Open or build an assembly (see Build an assembly).
2. Choose Clash.

The status bar reports the result:

• "No interference between 3 parts (40 ms)." Nothing overlaps.
• "Interference: Flange1 and Flange2 overlap by 2.5 mm³." Each overlapping pair, with the volume of the overlap.

The Assembly box on the left shows Interference: "None", "1 pair overlap", or "Not checked". With nothing selected, the right panel lists each overlapping pair and its volume.

The result is cleared whenever the assembly changes. Run Clash again after moving a joint.

Touching faces (parts face to face) are not a clash; only shared volume is. Every pair of parts is checked against every other, so large assemblies take longer.

Watch the motion

1. Select a revolute or slider joint in the list on the left.
2. Drag the slider under Angle (°) (revolute) or Offset (mm) (slider). The part moves as you drag.
3. Let go. The new position is kept and can be undone with ⌘ZCtrl+Z.

You can also type an angle or offset in the box and press ReturnEnter.

Sweep a joint for clashes

1. Select a revolute or slider joint.
2. Choose Check the motion for clashes.

PartCraft moves the joint through 25 positions in 24 equal steps: a revolute joint from −180° to 180°, a slider from minus to plus the size of the biggest part. It reports:

• "No clash anywhere from -180 to 180 (25 positions checked)."
• "6 of 25 positions clash, first at angle 45 (12.4 mm³)." The first position that clashes and the overlap there.

The button is grayed for rigid joints, which do not move. The sweep checks the positions only, not the path between them: a thin part could pass through another between two steps.