by Clint Brown
I was going to do a blog post explaining the new self-intersecting sweeps in Autodesk Inventor 2014, but I came across a very useful Forum post by an Autodesk Employee, Glenn Chun, which explains it perfectly. Below is a copy of the post, the original can be found here:
I've read some misunderstandings about self-intersecting sweep in this forum. I would like to clarify what's allowed and what's not.
There are three types of self-intersections in the Sweep and Coil features in Inventor:
Type 1. Single-face self-intersection
A face is not allowed to intersect itself.
Also, cross-sectional profiles are not allowed to intersect each other.
The above type is regarded as "illegal geometry" in Autodesk ShapeManager, the geometric modeling kernel for Inventor, AutoCAD products, and Fusion 360. We do not have any plan to allow this type in the future.
Type 2. Self-intersections around circular path segments
Not allowed in Inventor 2013 and earlier. Allowed in Inventor 2014 (a patent-pending technology). Make sure the profile plane is perpendicular to the path.
Sweep Cut example:
Sweep Join example:
Type 3. Face-face intersections
a. General case: Intersections between two different faces of the result body are not generally allowed in Inventor 2012 and earlier. Allowed in Inventor 2013 and later.
b. Coil case (sweep along helix): Not allowed in Inventor 2013 and earlier. Allowed in Inventor 2014.
The first example above has only one lateral face which intersects itself, so it belongs to Type 1. The second example has two lateral faces created from the two circular arcs of the profile. The polygonal profile doesn't need any special treatment because it creates multiple lateral faces.
The What's New documentation for Inventor 2014 shows Types 2 and 3b:
All of the above examples can be found in the attached zip file. You can open the parts in Inventor 2012 or later.
Hope this helps,
Autodesk ShapeManager Development