topic Re: Having trouble lofting these spines. in Fusion Design, Validate & Document Forum

Having trouble lofting these spines.

asbissonnette — Thu, 13 Feb 2025 19:39:51 GMT

I am sure this is a simple answer, but I can't figure it out.

I am trying to design a cover for my 3d scanner to print in TPU. I scanned it and have the mesh imported. I also created some 3d sketch outlines of relevant geometry in QuickSurface (I am learning QS) and imported them as Splines (I think). I also don't have much experience working in surface mode in Fusion. I am using the Hobby license.

My initial idea was to create surface lofts between the splines to use as a starting point to then build the cover geometry from, but I am getting an error stating the loft would intersect itself. I don't know why, but QS wouldn't let me create a closed profile for most of the splines - probably related.

EDIT: I patched each profile and had more success lofting some of the surfaces that way. However, when I try to loft the two resulting bottom surface where the scanner geometry ridges out, I get an error about multiple edge loops. What is causing this?

I attached the project file. ~~I am wondering why the loft wants to intersect itself for example between the bottom inner line and the upper line. If anyone knows why these self intersect, and or a fix for that let me know.~~ I am also open to a different design approach if you have an idea.

Re: Having trouble lofting these spines.

davebYYPCU — Fri, 14 Feb 2025 04:58:52 GMT

Fusion does not import geometry and then work seamlessly with that data.

Toggling the curvature combs, makes an interesting but predicable reason the Loft will not accept these sketches. Curve combs should be as smooth and even as possible and certainly have no sharp corners in the red outline.

You may find a better result using Mesh environment, and subtracting the scanner from an oversized blob, and then extracting a 2 half mold parting surface. Depends on what you are attempting.

Might help....

Re: Having trouble lofting these spines.

yqliu — Fri, 14 Feb 2025 06:54:47 GMT

There is a bug in the loft tool. The order to select the profiles might impact the result. In this case, if I select the lower curve first and then upper curve, the command will fail. But if I select the upper curve first, it will be successful.

(view in My Videos)

But switching the order will result in a failure:

(view in My Videos)

Re: Having trouble lofting these spines.

asbissonnette — Thu, 06 Mar 2025 15:36:36 GMT

Sorry for the late reply. I made these lines using Quicksurfaces "3d sketch" tool which works by selecting points on the mesh and then it very accurately traces tangent lines between each point. The scan is imperfect and the surface is not entirely smooth, and I think that gets embedded into the lines, which might be the reason behind the jagged combs.

I think in the end, that is exactly what I ended up doing - subtracting the mesh from a form object I made in the surface environment Thanks for your help.

Re: Having trouble lofting these spines.

asbissonnette — Thu, 06 Mar 2025 15:38:47 GMT

Yes, I found this out eventually. I also don't know why QS wouldn't allow me to make that bottom profile from one single line, I had to connect those points with a separate line Thank you for the help.