Surface Sweep goes in unclear direction, or two directions.

jl9J8Z6 · ‎08-31-2023

Hey,

I have an issue creating a surface sweep from a 3D profile in one direction.
I'm aware that the path should connect to the profile or better start off the profile toget a reasonable result.

In my current design, the path starts right of the 3D profile in one direction and still I get a sweep in two directions with the origin of the path (a straight line) somwhere along the path.

I tried to recreate the issue in a minimalistic example, as I can't share my current work, but only encountered the direction of the sweep to flip depending on how much percent of the path I do the sweep. Try it yourself with the example file.

In my actual work, the Issue changes every time I edit the feature (or calculate all) which is super annoying. I recorded a video of editing it and you can see that in the beginning the path is not going along the entire lenght of the path in both directions. Sadly I did not record the previous edit, as it went all the way there.
The jumps that happen seem to be an issue of the path origin jumping randomly during the creation or re-calculation of the sweep.

Is there a way to trigger the two directional sweep or trigger/define the path origin? I did not manage to do so in the minimal example.

TheCADWhisperer · ‎08-31-2023

@jl9J8Z6

Why are you using Sweep instead of Extrude?

Why are there so many segments in the sketch - can you show the sketch by itself?

Are your sketches fully defined.

Are there any unresolved issues highlighted in your Timeline?

Are you working within +- 100000cm of the Origin?

Now I will look at your example file and see if it answers these questions.

jl9J8Z6 · ‎08-31-2023

I use sweep, as the profile is the edge of a 3D face and not a sketch line on a plane.

There are so many segments, as the 3D face is an organic shape that was imported as step file.

Yes, all my sketches are fully defined, although Fusion fails to recognize this sometimes, especially when working with splines or projected splines.

Yes, there are unresolved issues in my timeline and each time I re-calculate the entire model, their number increases, I already spent one day on fixing them (usually it's just Fusion forgetting selections or miscalculating things that work once I edit the feature. But all unresolved issues are behind (to the right of) the timeline-curser. So afaik they should not cause this.
No, I'm working about 20cm away from the origin.

davebYYPCU · ‎08-31-2023

I would not use Sweep if it is unreliable.

extrude the tube, and split body / Trim with the object face/s.

Might help.....

jl9J8Z6 · ‎09-01-2023

I think this was not clearly formulated from my side.

I do not have a flat profile that I can extrude. I only have the 3D curve, so extrude does not work.
I just extruded the tube and split it in half with a spline to create a similar 3D curve/edge.

It's also not ideal to just not use a feature because it's unreliable. With all the bugs and non-parametric features, this gets so limiting that I could also just quit my job and don't use any CAD program anymore. (Sorry if this sounds offensive, that's not my intention, I'm just frustrated rn.)

TrippyLighting · ‎09-01-2023

I think the Sweep code its either buggy or not well implemented. Just as the loft tool occasionally responds with error messages that are demonstrably wrong, so does the Sweep tool.

In the attached example that creates the desired result it creates an error message that is demonstrably wrong.

The path clearly intersects the profile. I believe the implementation relies on sketch constraints to check for that intersection, but that fails in this case because you select an edge as the sweep profile. I've seen similar things in the loft tool.

I am tagging @Phil.E and @jeff_strater here. Phil to record this behavior and Jeff to make sure we get better and more robust implementations.

jl9J8Z6 · ‎09-01-2023

Yeah I'm afraid so. The revolve command is so, too. While the extrude command is super nice implemented, you can't revolve from/to a reference point. The option is there, but especially when revolving in two directions there is no option to define the direction of either selection, nor is it an actual selection. It simply meassures the angle and saves the value. And the resulting two directions chages their direction randomly when recalculating the model.
Really pity.

Also splines and 3D sketches tend to not show as fully constrained some times although they are.
And in my current design I have the problem that sketch constraints just vanish when one of the constrained geometry is projected onto the sketch, so my sketches start to float somewhere else and everything depending on them fails.

TrippyLighting · ‎09-01-2023

@jl9J8Z6 wrote:

Yeah I'm afraid so. The revolve command is so, too. While the extrude command is super nice implemented, you can't revolve from/to a reference point. The option is there, but especially when revolving in two directions there is no option to define the direction of either selection, nor is it an actual selection. It simply meassures the angle and saves the value. And the resulting two directions chages their direction randomly when recalculating the model.
Really pity.

Also splines and 3D sketches tend to not show as fully constrained some times although they are.
And in my current design I have the problem that sketch constraints just vanish when one of the constrained geometry is projected onto the sketch, so my sketches start to float somewhere else and everything depending on them fails.

I am not sure what that has to do with the invalid error messages. Can you demonstrate what you are talking about with the revolve tool?

jl9J8Z6 · ‎09-05-2023

The issues with the revolve tool have nothing to do with the invalid error message, but with the unclear and randomly changing definition of origin and direction of selected geometry. Sadly I can't reproduce that currently.

However, I changed something in the timeline which slightly changes the profile of my initial sweep issue.

Ofcourse this broke the sweep feature and if I now try to do a new sweep feature with the 3D profile, the sweep tool just goes crazy. I can't select the entire tangent edge as profile, although different selections indicate that the individual profile edges indeed are connected tangentially.
Further, I could somehow select the entire profile which got highlighted as "Guide Rail" dispite using the "Single Path" option without any guide rail?!

TrippyLighting · ‎09-05-2023

I am not sure what you are trying to model, but my guess is that the sweep tool is not the best choice for what you are trying to accomplish. The segmented nature of the sweep geometry in your screenshot is an indication of that.

Would you have a screenshot or a hand sketch of what you are modeling ?

Maybe we can find a way to model this that avoids these issues.

I am trying to say that the sweep tool is great. It occasionally has problems.

@jl9J8Z6 wrote:

... Sadly I can't reproduce that currently.

I run into these situations as well. Naturally I don't record everything second of Fusion 360 work, so sometimes that makes these intermittent issues very difficult to show.

jl9J8Z6 · ‎09-05-2023

I'm modelling a thin-walled housing with a removable cover piece, that has defined holes. The cause of the problems here is the 3D-curved outer surface of this housing. As stated in the beginning, this face is an imported step file and the reason for the segmentation of my profile. You can see an offset of the imported surface in my last screenshot. The major part of the 3D-face is hidden, but the patch you see is created by splitting the 3D-face using a spline (just like in my example file, but fully constrained).

My first approach was projecting the border of the 3D-face onto a sketch and extrude the resulting profile, but the result were many separated lines that all intersect each other but don't create a profile I could extrude. That's why I'm using a sweep.

This time I split the 3D-face in half, used the sweep on that half (as I could always select more than half the profile, but not the enitre one), and mirrored it. Yet another workaround for strange errors. (I also had two revolves in this design, which failed using the "join" and "cut" option, but creating new bodies and combining/cutting them with the target body worked flawlessly.

TrippyLighting · ‎09-05-2023

Without a model, I can't do much ...

AnswerBar4 · ‎09-05-2023

Thanks, that's not a helpful error message. Reported as FUS-138295.