Error Message - Shell Errors

Potential Error Messages

  • The shell operation failed to complete. One of the faces may offset into an adjacent face, a small face may need to be eliminated, or one of the faces may have a radius of curvature which is smaller than the shell thickness. Use Tools > Evaluate > Check to find the minimum radius of curvature on appropriate faces. If possible, eliminate any unintended small faces or edges.
  • The Thickness value is greater than the Minimum radius of Curvature. The shell may succeed, but could cause undesirable results, such as bad geometry. To find the Minimum radius of Curvature, use Tools > Evaluate > Check.

Potential Reasons for These Error Messages

Exceptions permit some shell errors to succeed. See Shell Exceptions.
Shell Error Examples

Face offsets into adjacent faces.

Shell fails with 1mm thickness setting. The model thickness at point shown is less than 1mm. The inner face offsets through the outer face.

Shell thickness exceeds the minimum radius of curvature.

Shell fails because the shell thickness setting exceeds the minimum radius of curvature for the model.

Some three-sided surfaces do not shell properly because of problems solving shells at the vertex.

Shells can fail when swept cuts using an existing model edge produce small faces along the resultant edge.

Potential Fixes and Tips

Potential Solutions:

  • Decrease shell thickness so it does not offset into adjacent faces or exceed the minimum radius of curvature. Use the Check tool on the Tools toolbar to find the minimum radius of curvature.
  • Add an extrude feature that covers the area where the shell offsets through an exterior face. Recreate the shell, removing all the extrude feature faces plus any model faces.
  • Remove unintended small faces or edges.
  • Use the Offset Surface tool on the Surfaces toolbar to offset surfaces you plan to shell. If you can offset the surfaces, you can probably shell them. In most cases, offsetting surfaces is testing the minimum radius of curvature.
  • Cut away areas of the model to pinpoint the problem area.
  • Work with the shell suppressed. Shelling complex parts requires a long time. Suppressing a shell lets you add and subtract faces from the shell without regenerating it. Work with the shell suppressed if you know it is going to fail, but you need to work on other parent features. Unsuppress the shell when you have fixed the problems with the parent features.