Loft feature

Uses for loft features

• Create a solid feature or new body.
  
• To generate the shape, create a surface model, and then stitch the resulting surface quilt into a solid.
  
• Create lofted surfaces and use with the Sculpt command to create a shape, or modify the model.
  

Sections in lofts

After you create the required initial two sections, you can create any number of sections to create the required shape. To control the loft shape between sections further, you can:

Add weight to a section.

No weight

Both sections with equal weight factors

To guide the sections, use loft rails.

To guide the sections, use a centerline.

Part faces or points in loft feature

For beginning and ending sections, you can select nonplanar or planar faces . For a natural transition, make lofts with tangential continuity (G1) or curvature continuity (G2) to adjacent part faces. In a G1 loft, the transitions between surfaces can be visible. A G2 blend is also called smooth , and appears to be one surface. It does not display the transition between surfaces when highlighting.

To use an existing face as the beginning or end section of a loft, select the face directly without creating a sketch.

For open lofts, you can begin or end a section at a point. Valid selections for lofting to a point include:

• Model vertices
• Model edge midpoints
• Work points
• Visible sketch vertices
• Visible sketch entity midpoints
• Visible sketch points

Note: When selecting a point, do not select the geometry the point is attached to. In this image, we picked the spline instead of the endpoint:

The pick results in an error message. Use Select Other until only the point highlights.

To create a sharp termination point, use Loft to a point with the Sharp Point condition (default).

To create a more rounded termination, use Loft to a point with the Tangent condition and a weight factor.

To create a rounded termination tangent to a plane, use Loft to a point with the Tangent to Plane condition, and a weight factor.

When specifying a centerline with a point section, the centerline must pass through the point section. For best results, pass it near the middle of the neighboring section.

Lofts between two-point sections must include an interior section to define the shape.

Transitions from one section to next

To set a boundary condition, use the Conditions tab. To control the shape and tangency of the loft surface, you can specify the transition angle (the default is 90 degrees) and the weight.

Weight is not a numeric distance, it is an influence factor. In other words, the weight factor controls the amount of influence the section shape exerts before merging into the next section.

In this example, both loft sections are set to the default Free Condition value. There is no angle or weight factor applied.

In this example, both sections are set to the Direction Condition. The rectangular loft section has a weight factor of 10 (10x) and the circular section has a weight factor of 5 (5x). The transition angle value is 90 degrees for both sections.

In this example, both sections are set to the Direction Condition. Both sections have a weight factor of 10, and a transition angle of 90 degrees.

In this example, both sections are set to the Direction Condition. Both sections have a weight factor of 10. The rectangular section has a transition angle of 90 degrees (perpendicular transition). The circular section has a transition angle of 180 degrees (planar transition).

In this example, both sections are set to the Direction Condition. Both sections have a weight factor of 10, and a transition angle of 180 degrees.

The relationship between the weight setting and how abruptly the loft surface transitions depend on factors such as the section shape and the distance between sections.

Rails or centerline in loft shape

Rails are 2D curves, 3D curves, or model edges that specify the loft shape between sections. You can add any number of rails to refine the shape of a loft. A rail affects the entire loft body, not just the section vertices which it intersects.

Neighboring rails influence section vertices without rails. Rails must intersect each section, and must terminate on or beyond the first and last sections. When generating the loft, the software ignores any portion of a rail that extends beyond a section. Extending a rail beyond a section is a useful technique to achieve a smooth shape. Rails must be tangent continuous. In this example, two rails extend beyond the start and end sections to achieve a natural transition.

A centerline is a type of rail to which the loft sections are held normal, which causes behavior similar to that of a sweep path. Centerline lofts maintain a more consistent transition between the cross-sectional areas of selected loft sections. Centerlines follow the same criteria as rails, except they need not intersect the sections, and you can select only one.

Merge Tangent Faces options

When loft sections contain vertices, the resulting loft contains multiple faces separated by edges created between the section vertices. For example, a loft between square sections results in four lateral faces.

Sometimes a loft represents a complex, organic shape, as in some in consumer products. Such edges are often unwanted, especially between G1 tangents or G2 smooth faces. To remove unwanted edges between tangent or smooth faces, where possible, use the options for Merge Tangent Faces.

Uses for area loft

Area loft supports the design of hydraulic and pneumatic components, manifolds, and molded plastic parts. In these and other designs, the flow of gas or liquid is critical. Area loft provides greater control of cross-sectional areas at specified points along a lofted feature.

With Variable Radius Fillet, you pick points on an edge and define radius values. Similarly, use Area Loft to pick points along a centerline. Define either a cross-sectional area , or a scale factor at those points that scale a loft up and down accordingly. To apply aesthetic changes to a loft, use Area Loft.

Area Loft follows the same criteria as Centerline Loft. You place sections along the centerline. But unlike Centerline Loft, Area Loft attaches editable section dimensions to the selected sections, and to any placed sections.