Complex Sweep2 (How to solve)


I’m currently in the proces of doing a 2 rail sweep on a rather complex part. And so far I’m not satisfied with the result. I was wondering if anyone would be able to do a better job.

This is the problem:

Problem.3dm (96.4 KB)

And here is my best attempt:

Best_Attempt.3dm (358.1 KB)

There is still a slight fold in the surface. And I was hoping there was a way to fix this…
Does anyone know a better technique to solve this problem?


In the end a history enabled Sweep2, followed by dragging the curve control points in ControlPolygon DragMode was the perfect solution to this problem.

Case closed.


Here you go
Problem-ans.3dm (299.6 KB)


You might want to _MatchSrf on point 2 as well but it looks good.

(Pascal Golay) #5

Hi @Stroopwafelandcoffee , Luc - try this:

  1. MergeEdge on the short edges at the end of the sweep.
  2. DupEdge there and select the curve.
  3. Start -Rebuild, with a dash in front. At the command line choose ‘SelectMasterCurve’. Select one of the nice cross section curves you have in place. DeleteInput = Yes. The effect of this is to make that curve match the structure of the clean curves you have. This allows the sweep to be much cleaner.
  4. Sweep2 asking for curvature continuity along both edges.

Best_Attempt_PG.3dm (338.5 KB)


-Rebuild (with MasterCurve) while retaining the original shape

Sorry to bring this to the surface again but I have a question. In the image attached: A is how the original 2 rail sweep looked (isoparms); B is how it looked after deleting the rail extrude,merging both rails, splitting in the same place and re-extrude; C shows the nasty bulge that results. Does splitting an edge then merging it change the surface? I haven’t noticed this before.


But “-Rebuild” will not conserve the shape of that curve, which is crucial.

EDIT: I see that your curve is exactly the same as the original curve, did you do this manually or am I missing something?