Troubleshooting: Addendum Surface Issues


If you encounter any of the following issues, try the remedies below.
  • No addendum surface is created.
  • There are missing surfaces and a partial addendum is created. Red indicates locations where the addendum surface failed to propagate.
  • There aren't enough ribs.

Step 1: Fix Overlapping Ribs

Overlapping ribs is the most common issue, so we suggest starting off by fixing them manually.

  1. Adjust the view as necessary to locate overlapping ribs.
  2. Rotate the ribs so that they don't overlap by doing one of the following:
    • Hover over the rail to display handles. Drag the lower arrow to change the angle of the rib plane.
    • Select a handle and enter an Angle in the microdialog.
    Note: If a rib can't be rotated, select the rib, and in the microdialog turn off the constraint Tangency G1 to the part so that you can rotate it.

    Figure 1. Issue: Overlapping Ribs

    Figure 2. Remedy: Rotate Overlapping Rib

Step 2: Delete Excess Ribs

Check for ribs that are too close together or lie on the same plane, and then manually delete excess ribs.

  1. Adjust the view as necessary to locate ribs that are too close together or lie on the same plane.
  2. Delete ribs as necessary to smoothen the flow.
    1. In the guide bar, select Edit Ribs.

    2. To delete a rib, select it and press Delete.
      Note: If the rib is essential for maintaining the desired addendum shape, instead of deleting it, you can rotate it as described above.

      Figure 3. Issue: Excess Ribs

      Figure 4. Remedy: Delete Excess Ribs

Step 3: Add Ribs

You can add ribs automatically and manually. Once you've added ribs, you can edit them to adjust the addendum.

Step 3A: Add Ribs at T-Intersections

Not enough ribs were created by default (only at Discontinuity vertices). These include vertices, points, or locations on the part edge where tangency discontinuity is greater than the specified Edge discontinuity tolerance. In the modeling window, discontinuity vertices (and corners) are indicated by red dots.

Figure 5. Issue: Not Enough Ribs Created with Default Auto Create Rib Location Option
To bring in more ribs, in the Control Panel, for Auto create rib locations, select T-intersection vertices. These include vertices, points, or locations where internal edges meet with external edge forming T-intersections and discontinuity vertices.

Step 3B: Add Ribs at All Vertices

Still not enough ribs were created automatically when you selected T-intersection vertices.

To bring in even more ribs, in the Control Panel, for Auto create rib locations, select All vertices. This includes all vertices, points, and locations on the part edge (vertices on the edge, T-intersection vertices, and discontinuity vertices).

Step 3C: Restore Missing Ribs at Discontinuity Vertices

Check for missing ribs at discontinuity vertices and add ribs there.

  1. Adjust the view to locate discontinuity vertices where there are missing ribs.
  2. Hold down Alt while hovering over an addendum start edge, looking for green dots (discontinuity vertices) where there are missing ribs, and click these green dots to add ribs there.

Step 3D: Add Ribs at Custom Locations

You can add ribs at custom locations (for example, at long stretches without ribs or at corners to help the surface make a turn).

Do one or more of the following:
To Do this Notes
Create a copy of a rib
  1. In the guide bar, select Copy Rib.
  2. Select the rib to copy.
  3. To paste a copy of the rib, Alt+click.
Add new ribs
  1. In the guide bar, select Edit Ribs.
  2. First hold down Alt while hovering over an addendum start edge, and then click a blue or green dot. A green dot indicates a sharp corner where edge continuity is broken.
Copy some parameters of a source rib to target ribs
  1. In the guide bar, select Pass Rib Parameters.
  2. Select the source rib.
  3. To select the target ribs, do one of the following:
    • Alt+click
    • Right-click, and then select Select ribs except source or Select ribs of same type.
  4. To copy the parameters from the source to targets, right-click, and then select Update.
The following parameters are passed on:
  • Addendum configuration
  • Angle
  • Length
  • Tangency (G1) to the part
  • Radius
The following parameters are not passed on:
  • Rib plane orientation
  • Align to XY draw plane
To pass these 2 parameters from the source ribs to the target ribs, see Auto-align Ribs below.

See Rib Options for parameter definitions.

Figure 6. Issue 1: Long Stretch Without Ribs

Figure 7. Remedy 1: Add Ribs at Custom Locations to Build Addendum Surfaces All Around

Figure 8. Issue 2: Addendum Wall Doesn't Follow the Part Edge

Figure 9. Resolution 2: First Add Ribs at Corners To Help Addendum Surface Turn Properly

Figure 10. Resolution: Then Add Adjacent Ribs to Align the Addendum to the Part Edge

Step 3E: Relax the Tangency to Propagate the Addendum

Important: This remedy only works if you already have a partial addendum. It doesn't work if no addendum surface was created at all; in this case, you need to add ribs to create a partial addendum first.
By default, Tangency (G1) is used, creating ribs with tangent (G1) continuity between adjacent addendum surfaces. In some cases, this is not feasible, causing the addendum surface to fail to propagate. By turning on Auto Decide Tangency, you can see how far the surface can propagate and identify regions that require manual fixes.
  1. Hover over a rib to display the blue handles, and then click one of the handles.
  2. In the microdialog, for Addendum configuration, select Auto Decide Tangency. This uses G0 when G1 is not feasible.

    When Auto Decide Tangency is set, the rib is displayed in yellow.
  3. As necessary, repeat Steps 2-3 on other ribs until the addendum surface is fixed.
  4. The default Tangency (G1) is the ideal addendum configuration, so you can try turning G1 back on for earlier ribs if it doesn't break the surface.

    Figure 11. Issue: Addendum Surface Fails to Propagate with Tangency (G1)

    Figure 12. Remedy: Turn On Auto Decide Tangency to Propagate Addendum Surface