A basic swept feature has a single trajectory and a constant (unchanging) cross section.  The same feature can have an initial cross section which is referenced to multiple trajectories which influence (distort) the section as it travels along those trajectories.

In the example below a rectangle is swept along the 2 curves projected onto the curved surface.  The 2mm depth of the rectangle is unchanging but the height is connected to the 2 trajectories and is controlled by their position – the cross section varies.

 

 

So why not a Blend? We could produce the form above with a Swept Blend feature but the system would dictate what shape was formed between the blend sections.  With the sweep we have precise control over the section at every point along the trajectories.  We can subtily tweak the curves to change the form.

Because the section changes, you cannot use an existing sketch or edges for the sketch as it would then be referenced to those entities and not be able to ‘distort’.  As you cannot reference to a start or end section this would not generally be used as a infill volume between existing end sections – consider a Blend.

Section behaviour – how the cross section orientation varies as the form is developed along the trajectory.  Read Sweep – section control before proceeding.

 

Construction

  1. Activate the Sweep  tool
  2. Select the Origin trajectory
  3. Ctrl select further trajectories to control section
  4. The variable section icon will activate in the Dashboard
  6. Enter the sketch environment from the Dashboard
  7. Create the section appropriately connected to the chosen trajectories

 

Key points:

  • trajectories must be tangent chains
  • the dimensioning scheme must be carefully considered – which dimensions are fixed and which are allowed to vary
  • dimensions of the section may vary but not the fundamental geometric elements
  • a high level of control is maintained over the resultant form
  • reference to existing geometry with care
  • sketchplane placement is greatly effected by chosen trajectories and which is the origin
  • there is a need to experiment with the combination of setting in terms of origin trajectory selection and section control

 

Sketchplane

The sketch plane must intersect all trajectories and therefore may not be set on the end point of the Origin Trajectory.  The resultant solid cannot extent beyond the selected trajectories and therefore the trajectories need to be carefully considered in terms of the section orientation control.