T-Spline Surface Is Invalid Error

[aaronsgreen]

I sculpt a body, then try to finish it but it throws this error every time: T-Spline Surface Is Invalid

If I continue, the body disappears.

If I double-click on the body/sculpt on the timeline it returns me to the body in sculpt mode, but I can't get it back to model mode to continue working on it.

There's nothing that crazy about the body either. I don't understand why sculpting would allow me to perform edits that aren't 'legal' for modelling. It says I can stay in sculpt mode to 'fix the errors', but I have no idea what specific errors it's referring to.

What I did was create a polygonal sketch, extrude it 2mm, fill the top and bottom holes, subdivide the entire body, remove the edges running out to the corners, then add points across the corners so I could move the vertices down on the Y axis to create a rounded hex nut.

I also don't know why the point-to-point edges I inserted are wobbly? They didn't appear like that in the preview...

[Anonymous]

Usually, it's due to self intersection of body faces. Have you tried to run Utilities -> Repair Body?

Anyway, I could not say what's the issue exactly, because Fusion 360 claims that the file you attached is broken.

[PhilProcarioJr · Accepted solution]

@aaronsgreen

Your using triangles....never use triangles in your T-Spline forms ever. Just some friendly words of advice.

I can't open your model as it says it is corrupted for me, but delete the edges I have marked in red and see if that helps.

[aaronsgreen]

I tried Repair Body > Auto Repair, but it didn't fix it.

Then I fussed around with the features and the body and found the the 'T' icons on the body can be selected and turned into Gold Stars, then it passes Finish Form successfully.

Can anyone explain that process? I haven't seen this explanation in the help documents yet.

[aaronsgreen]

If I subdivide the hex in a different workflow, it avoids the T-Spline error all together, but I don't know why it works. In this case, instead of deleting the edges that go to the corners first, I added the edges across the corners first, then deleted the shorter edges that ran to the corner.

Why shouldn't I work with triangles in sculpt mode? If I extrude a hex sketch, and file the holes, it has triangles in it, and will convert to a model without error. There's an issue with it adding edges in after edges have been deleted. It doesn't like it. I also noticed that it doesn't remove the vertices when I remove the associated edges.

[josephacthomson]

thanks man, you helped alot with a persistent issue ive been having, those **** triangles!

[adamhutz]

I was struggling with a similar error to this in a 2023 update. I was able to turn all of the "Ts" into stars, but still couldn't finish the model. Clearing symmetry is what solved it for me.