Warning: Sweep - Reference Failures - The operation failed due to coincident control points.

[Anonymous]

Hello again, after few problems with API scripts, I finally realized my "import from csv tool" and I can now have issues with the real design 😅.

• I created 2 sketches, one with a profile and one with a sweep path.
• I pushed Surface >> Sweep
• I filled the command with the following settings:

• I can see the object preview
• When I press "ok", few seconds later I got the following error:

Warning: Sweep2 1 Reference Failures
The operation failed due to coincident control points.
Try adjusting the values or changing the input geometry.

I really don't know why, I tried to find here in the forum and online, but I didn't get a clue 😣

I attached also the file if it could help to find out the issue

Thanks

Luca

[jhackney1972]

The Fit Point Spline you are using for the path is the issue.  Not sure what points are the issue but since it is basically a perfect ellipse substituted one for the path.  The sketch still contains the spline.  Model is attached.

[davebYYPCU]

So many spline points.  I do airfoils with 2 four point splines for best results.  Your inside profile would be the exception.

No inside profile, of the wall sketch, how can that be?

Try one outline per Sweep.  Solid Sweep fails?

sorry I have no access to files till after Easter.  

I am thinking no profile, somewhere to look.

Might help...

[TrippyLighting]

Have you checked the curvature of the spline you create by connecting all the imported points?

There are mathematical reasons that it looks as terrible as it does. 

In essence, however, I would use the imported points only as a visual guideline to create the needed geometry with native Fusion 360 sketch objects.

[Anonymous]

Thanks, the problem was actually the path spline!

[Anonymous]

Thanks for the reply, solid sweep fail as well.
Thanks to @jhackney1972 I solved, the problem was infact the path spline.

[Anonymous]

The shape spline is good, actually as @jhackney1972 made me notice, the problem was the simple part: the path spline!

[TrippyLighting]

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@Anonymous wrote:
The shape spline is good, actually as @jhackney1972 made me notice, the problem was the simple part: the path spline!

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No, the shape of the spline is garbage and the curvature comb shows that in no uncertain terms! 

You can put a Band-Aid on this and move forward, but chances are that you'll run into other modeling problems with this approach.

[Anonymous]

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No, the shape of the spline is garbage and the curvature comb shows that in no uncertain terms! 

You can put a Band-Aid on this and move forward, but chances are that you'll run into other modeling problems with this approach.

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Ok, for sure you're right. But saying it's garbage without explaining why, it's been useful on a forum like my spline in a design process 😂

I'm curious about understanding what I did wrong and what I could learn/looking for to improve my skills (which are merely zero at the moment). That spline has been parametrically generated by a MatLab script just in part modified by myself.

Thanks in advance for the suggestions!

Regards,

Luca

[TrippyLighting]

Right, I do need to explain that.

The curve you generated in Matlab followed an algorithm and perhaps math that is not equal to how fit-point splines and their math are implemented in Fusion 360. Fit-point splines in general are implemented differently in different CAD and modeling applications.

As such the points your algorithm created might lie on a curve but that curve is not a fit point spline. In Fusion 360 a fit-point spline is a 5-degree multi-span spline. Unless the points calculated by the algorithm in Matlab coincide precisely with the control points of a fit point spline as implemented in Fusion 360 the result is as shown in the screenshot I provided.

Generally when working with splines less is more. Use the least amount of points you can get away with and control the shape with the tangent handles.

[Anonymous]

Thanks for the explanation @TrippyLighting,  but I didn't understand how can be different import points or setpoints directly in F360. Let's say that I draw 10 points (x, y) as I was working in 2d on a sketch. F360 will try to draw the line by interpolation with its defined polynomial function. The more these points are in a non-linear position, the greater will be the order of the polynomial (to simplify). Then what's the difference if the 10 points were imported? 

Maybe in Matlab, the function which draws the line to connect them is different, but I didn't force F360 to follow that "path", I just gave the point to pass through. I don't get the point, sorry I'm dumb 😅

[davebYYPCU]

Point to pass through, no

in Fusion - it’s place spline point here.

There is no need for so many points, and importing so many is a backwards step.

I always make my airfoils in Fusion, from 2 splines with 4 data points each.

Might help....