topic Re: Strange behavior when sweeping along a path comprising multiple splines in Fusion Support Forum

Strange behavior when sweeping along a path comprising multiple splines

ginavenolia — Sun, 28 Feb 2021 03:39:46 GMT

I am getting some unexpected behavior, which may be a bug (although I am a bit of a noob, so it may be pilot error??). I want to create a sweep along a path made of multiple splines, so that the resulting body has corners among the curves. Think of a heart, which has an "inside" corner and an "outside" corner between two curves.

Create a sketch
Draw an open spline
Draw a second spline starting and ending at the first's endpoints, creating a closed path
Create a plane on path
Create a sketch on the plane
Create a closed shape to sweep
Perform the sweep of the second path along the first
Show the first sketch
Drag the first "corner" down to change it from an "outside" corner to "inside" - works as expected, you can make a lovely heart
Drag the first corner up to return it to being "outside"
Drag the second corner up to turn it to "inside" - an error occurs*
With the second corner "inside," drag the first corner down to turn it "inside" - now only half the sweep occurs, though no error is reported

This condition occurs regularly in my work, where I want to create a symmetrical spline path using a mirror command and/or spline paths with corners.

Thanks,

-Gina

*Warning: Sweep1 <b>1 Reference Failures</b><br> There was a problem combining geometry together.<br> If attempting a Join/Cut/Intersect, try to ensure that the bodies have a clear overlap (problems can occur where faces and edges are nearly coincident).

Re: Strange behavior when sweeping along a path comprising multiple splines

ginavenolia — Sun, 28 Feb 2021 03:41:08 GMT

PS. I added a screen cast to my post, though I don't see it here. Please check my profile for my one and only screen cast

Re: Strange behavior when sweeping along a path comprising multiple splines

g-andresen — Sun, 28 Feb 2021 10:07:33 GMT

Hi,

The cause:
Some courses of the path lead to self-intersections of the profile.

You could do the sweep only partially and close the remaining gaps with additional measures (e.g. loft).

günther

Re: Strange behavior when sweeping along a path comprising multiple splines

ginavenolia — Sun, 28 Feb 2021 21:17:31 GMT

Here are some screenshots to illustrate the problems I'm seeing...

After Step 8 above, everything looks good.After Step 9, things are still looking good: I made a heart!After Step 11 this is the first unexpected behavior: I couldn't make and upside-down heart, even though it worked right-side up??? The error message says something about combining geometry.After Step 12 things are weirder still: Only half of the sweep appears, even though there is no error message.

Re: Strange behavior when sweeping along a path comprising multiple splines

ginavenolia — Sun, 28 Feb 2021 21:21:05 GMT

I don't think that's what's going on. In the first unexpected behavior the error report isn't complaining about self-intersecting geometry. In the second unexpected behavior there's no error report at all. Please see my recent screen shots that illustrate this behavior more clearly.

Re: Strange behavior when sweeping along a path comprising multiple splines

g-andresen — Sun, 28 Feb 2021 21:28:31 GMT

Please be so kind and share the design.

Günther

Re: Strange behavior when sweeping along a path comprising multiple splines

ginavenolia — Mon, 01 Mar 2021 21:07:58 GMT

I put all four cases into a single design to illustrate the behavior. Here's the public link: https://a360.co/3sANAQX

Note: The fourth case behaves slightly differently in this example: The top handle must be in line with the second handles of the two splines to get the behavior of half the geometry and no error message.

And here's a screen shot of the four cases: