Read previous section Blend – section influence first

As the name suggests, the Swept Blend tool combines the functionality of the Sweep and the Blend.  In this case the volume is not form along the shortest path between the sections, the trajectory influences the form.

Initially start with just two sections set at the ends of the trajectory, add intermediate sections if needed but consider their position and orientation if you want the trajectory to maintain its influence.

 

 

 

Most of the process can be achieved through the RMB menu:

 

 Activate the Swept Blend tool

 

Dashboard Options

 Solid or surface?   Protrusion or Cut?  Thin?

This feature defaults to surface, so pick solid if that is what you want

A closed sketch will produce a volume which can add or subtract material

An open sketch will produce a Surface feature or a Thin feature.  The thin option thickens an open sketch – useful for sheetmetal parts.

 

Trajectory

A trajectory needs to be defined before you can proceed to the sections.

Although it may not have an influence on the final form, the Swept Blend needs a trajectory, it could be as simple as a straight line or an existing edge.

The blend will only be created as long as the sections are within the extents of the trajectory – make sure the trajectory starts before the first and extends past the last section.

See chain of edges selection for trajectory selection.

 

The trajectory may be all or part of a sketch or a number of edges, consider the chain of edges selection process.

External Sketches

The default process is to create the blend section internally to the feature once the trajectory has been selected.

Creating your trajectory and sections as separate external features is a more efficient strategy as you can visualise the form and you will not lose your construction geometry if the feature is deleted

RMB menu >  Selected Sections

 

Sections 

Sections can be sketched curves or chain of edges – the sections must be planar

Section planes do not have to be parallel

Make sure you select the section nearest the start point (arrow end) of the trajectory.

  • Select the initial section
  • RMB menu > Insert section
  • Continue inserting sections

 

Start point

If the previewed solid is twisted because the start points are not aligned, simply drag the start point marker to the appropriate vertex.

 

No Preview?

First thing to check is the number of vertices in each section – this must be equal

In the example above we need to abandon the feature and equalise the number of  vertices in the underlying sections.  The most common solution is to increase the vertices to the highest count.

 

Blend Vertex

You may have a situation where you have an unequal number of vertices but its not appropriate to split one of the curves because you want multiple points in one section to blend to a single point in the next – imagine a square blending to a triangle.  In this case you need to add a Blend Vertex – basically a point on a point to increase the vertex count.

Continue the process as before.  When you come to the section which needs a blend vertex use the Add Blend Vertex button in the Sections tab.  The extra point will show as a white square, drag this to the appropriate vertex.

You CANNOT have a blend vertex on the Start Point, if they coincide, move the start point on your sections

 

Tangent end conditions

If the feature is joined to a suitable geometry you can use the end condition markers to set tangency.  In the below example some simple control surfaces were created prior to the swept blend feature to enable setting tangency.