Hints and Tips with the Modify 3D Command

• Blending Tips
• Redo Blend Tips
• Move Faces Tips
• Taper Faces Tips
• Advanced Taper Tips
• Offset Faces Tips
• Align Faces Tips
• General Modify 3D Tips
• More Tips for Effective Blending/Chamfering

Blending Tips

1: Blend Suppression Tips

• Problem:

A Modify 3D operation needs to redo a blend adjacent to the modified faces. However the blend could not be suppressed because its structure may have been destroyed by a previous modeling operation.

• Possible Solutions:
• Try to remove the blend with a machining or align command (picture 2) and recreate the blend after performing the Modify 3D operation (picture 4).
• Try to switch off Redo Blend if the intent of the modification allows.
• Try to use the Redo Blend control mechanism in order to avoid the suppression of the blends that could not be suppressed.

2: Redo Blend Tips

• Problem:

A Modify 3D operation needs to redo a blend adjacent to modified faces. The blends could not be recreated after performing the Modify 3D operation (picture 1). This might happen because:
• The Modify 3D operation created new edges that would also need blending.
• The Modify 3D operation did not leave enough space for the blend to be fitted into the model.

• Possible Solutions:
• Try to remove the blend before the operation. Perform the requested operation and apply the modified (in this example, the smaller) blend as necessary afterwards (picture 2). Add blend radii to the newly created edges.
• Try to use the Redo Blend control mechanism in order to avoid suppression of the failing blends if the intent of the modification allows.

Move Faces Tips

• Problem #1:

The moved face loses contact to a previous neighboring face. In the following example (picture 2), the cyan cylinder does not intersect with the moved planar face.

• Possible Solutions:
• You may need to add more faces to the move operation
• Make sure that the move face still has contact to the neighbor faces by extending geometry (freeform only) using an Untrim operation
• Problem #2:

The move face would create a gap in the model that cannot be closed by extending neighbor faces, but would need to create additional faces.

• Possible Solution:
• Move the faces one after the other. For moves with a single face the necessary faces to fill the gaps can be automatically created for many cases.
• Use the Lift command (as shown in the picture 2) since that will insert new side faces in the model first, then move the remaining faces (pictures 3 and 4)
• For more tips, see General Modify 3D Tips.

Taper Faces Tips

• Problem #1:

This type of surface cannot be tapered with standard taper. Only planes, cylinders and cones can be tapered. For cylinders and cones, the axis needs to be parallel to the draft direction. (The face normal of the red face in the example is not parallel to the cylinder axis).

• Possible Solutions:
• Use a draft direction parallel to the cylinder and cone axis (in the above example, the bottom face was used).
• Use the Advanced Taper command that allows tapering of freeform geometry and cylinders and cones whose axis are not parallel to the draft direction.

• Problem #2:

The face normal of a selected face is parallel to the draft direction. This face cannot be tapered since it would vanish by definition.
• Possible Solutions #2:
• Remove the problem faces from the selection list.
• For more tips, see General Modify 3D Tips.

Advanced Taper Tips

• Problem #1:

One or more of the fixed edges are parallel to the draft direction. This would lead to a corrupt taper surface. In the example below the red face must not be used as a fixed element since the edge common to the fixed face and the taper face would be parallel to the draft direction.

• Possible Solutions:
• You need to use a different draft direction.
• Do not specify the parallel edges as fixed edges (see picture 2).
• Problem #2:

Different draft angles are specified for different faces of a tangential face set
• Possible Solutions:
• Faces that are tangentially connected need to be tapered with the same draft angles
• For more tips, see General Modify 3D Tips.

Offset Faces Tips

• Problem:

Offset surface may become self-intersecting. If the curvature radius of a face is smaller than the offset distance, the surface will become corrupt or it will vanish when it is offset.

• Possible Solution:
• Use a smaller offset distance that avoids self-intersecting surfaces.
• Use the surface analysis command to check which values are the maximum possible.
• Problem:

Offset surface loses contact to a neighboring face. This may happen if an adjacent face is tangentially or nearly tangentially connected to the offset face.

• Possible Solution:
• Use the Lift command to add new faces.
• Offset the neighboring faces with the same value also.
• For more tips, General Modify 3D Tips.

Align Faces Tips

• Problem #1:

Align might create a wrong or no solution because of the incorrect "opposite" setting. For closed faces like cylinders and tori this may make a difference in selecting from multiple possible solutions.


• Possible Solution:
• If the face normals of the change face and the reference face of the expected result is flipped by approximately 180 degrees you need to activate the opposite option.
• Problem #2:

The geometry of the reference face is not large enough to come into contact with all neighboring faces of the changed face.

• Possible Solutions:
• Add the faces that do not touch the reference face to the changed faces (here the small side faces of the block).
• For freeform geometry use the Untrim command to enlarge the reference geometry until it intersects with all neighbor faces.
• If there is no connection (intersection) with all neighboring faces of the changed faces, the align operation fails.
• Problem #3:

The change face may have a tangential neighbor that does not intersect with the reference face.

• Possible Solution:
• If you want to replace more than one face of a tangential face set you need to specify all faces of the face set at once (multi-face align)
• For more tips, see General Modify 3D Tips.

General Modify 3D Tips

• Problem:

Freeform Surface Enlargement:
During a modification using either move, offset, taper, change radius or align, the operation often needs to enlarge freeform geometry. Often, the modified faces itself as well as the direct neighboring faces of the modified faces potentially need enlargement. Depending on the shape of the surface the enlargement distance might be limited or the surface might become self-intersecting or corrupt in the enlarged area. The Modify 3D commands try an automatic surface enlargement. However, this is limited to avoid enlarging the surfaces by more than their current size.

• Possible Solutions:
  • Avoid generating freeform surfaces whose borders meet at a corner point nearly parallel or antiparallel. Generate more than one surface instead.
  • Avoid generating freeform surface that are of strongly "tapered" shape.
  • Use Untrim command with the replace geometry option if the automatic extension (twice original size)is not sufficient but can be safely extended.
  • Use Untrim command to visualize how far the surface can be extended. If the extension is not the desired one, you need to modify the surface or add an additional surface using methods from the surfacing module like "extrude face" or "loft to part". (In the following example, loft to part was used.)
  

Tips for Effective Blending/Chamfering

Note: Although this section is not new with release SolidDesigner 2001, the graphics have been enhanced and some of the workarounds modified to reflect improvements. It is included in this training for completeness.

There are several situations in which the blending or chamfering of one or more edges is problematic. Some need an automatic fix, others may require the use of a workaround before the desired result is achieved. The following examples and their descriptions will give you an idea of these more complex blending/chamfering tasks (click the graphic to find the solution):

	The blend/chamfer interferes with 3D geometry like a boss or pocket that is not attached to the edge you intend to blend/chamfer.
	The blend/chamfer intersects with a face or edge that is not directly attached to the edge you intend to blend/chamfer.
	The blending/chamfering is tried on two edges, one concave and one convex, meeting in one vertex.
	The blending/chamfering is tried on two edges, one concave and one convex, meeting as tangents.