Hi Anis, this is due to one of the rails being made up of 3 segments.

Currently MoI handles sweeping differently than Rhino in the presence of multiple segments.

If you use Edit/Separate on those rail curves, you'll find this small segment here:



Which as you can see corresponds to the problem area of the resulting sweep.


If you fuse those segments together into a single segment by deleting the control points on the ends of that small segment in the joined-together curve, the sweep should behave better. Also another alternative is to use the Rebuild or FitCrv commands inside of Rhino to fit one single segment to that multi-segment curve.

Network in MoI will also work better for this particular case because it has a similar kind of refitting process done on all of its curves internally.

I have an overhaul of sweep planned for a bit later on in v2 that should address these issues with sweep.

- Michael