# Swept Surfaces

## How to create a swept surface when the center curve is neither continuous in tangency nor planar?

In the Swept Surface Definition dialog box, the "Deviation from Guide" option defines the gap authorized between the guide curve and the swept surface. With the default option, there is no gap. When this option is activated, the sweep algorithm tries to generate a surface that does not necessarily stick to the guide curve but is of better quality or enables the completion of the sweep operation. The "Angular Correction" option is related to the angular tolerance of the moving frame (that is the plane that moves perpendicularly along the guide curve).
Here is an example of a swept surface with a reference surface and a guide curve that is not continuous in tangency.
The discontinuities are located at the face junction on the reference surface. You can use the Curve Smooth command to check the guide curve continuity.

### Workarounds

Apart from specifying a new guide curve (either continuous in tangency or planar), you can:
• Check the "Deviation from guide"(s) option in the Swept Surface Definition dialog box. That way, you authorize a gap between the guide curve and the sweep itself. But the generated sweep will not stick to the guide curve.

• Check the "Angular correction" option. It is related to the angular tolerance of the moving frame (that is the plane that moves perpendicularly along the guide curve) and also has an effect on normal evaluation if there is an angular constraint on a support along guides (for instance, a sweep line with reference surface).

• Smooth the guide curve. If you intend to create a sweep with a reference surface, you must specify the reference surface as support in the Curve Smooth Definition dialog box.
For further information, refer to Smoothing Curves.

## How to create a swept surface when the extrusion of the vertex of the profile leads to a cusp?

When creating a multi-profile sweep, the parameters affecting the resulting surface are the shape of the profiles, their number and the way they are positioned, the guide curvature, etc. In the example below, the sweep is twisted because it is over-constrained by two many profiles.

### Workarounds

• Reduce the number of sections: the less the surface is constrained, the lower are the chances to generate a twisted surface.
• Search for an internal section with a disproportionate coupling along the guides. This section is to be removed. Here, the length ratios for the highlighted profile are respectively 0.58 and 0.97.
• Locate the twisted areas and search for the profiles in the neighborhood of the retrieved vertices. Remove these profiles from the list of profiles.

For further details about swept surfaces, refer to Creating Swept Surfaces.