Simple surfaces not able to use thicken command

[chriseder95]

Hi Guys, i need your help here, i'm working on a design project where I added a curved ending to a spline-based surface. 
i finished my design model and found that I could not thicken up the surface model to a body. 

i tried to revert what surface is causing the issue and found the following still relatively simple body not to be able to thicken up. 

Can anybody help me understand what causing f360 to not thicken this up, and how to avoid this in 

the error message is not helping, just saying cannot make it. 

please find the file attached. 

Looking forward to your help 🙂 thanks, guys 🙂 

[TrippyLighting]

@Phil.E this is one of those strange instances where I export he surface in STEP format, open it in Fusion 360 and thickening works without hesitation. Yet , with the native model in Fusion 360 it reliably refuses to do so. 

This one is particularly baffling, because it is indeed simple geometry!

[TrippyLighting · Accepted solution]

I think the culprit here is the sweep command ad for some reason the geometry it creates.

If you restructure the timeline a little, it works:

[TheCADWhisperer]

@chriseder95 

I did not dig into your geometry construction - but first thing I notice is that it is not symmetrical where I would probably expect to see symmetry...

[Phil.E]

The problem is with sweep. Bug logged FUS-145625. If there is a workaround, I will ask for the error message to be improved. 

I don't have time to check, but what if the sweep starts at one end, rather than in the middle? (just an idea for a workaround, not dismissing the importance of fixing any bug that exists here)

[jeff_strater]

"this is one of those strange instances where I export he surface in STEP format, open it in Fusion 360 and thickening works without hesitation" 

This is actually not all that strange.  Export via STEP or IGES involves an approximation of some kinds of surfaces in Fusion.  These are "procedural" surfaces (sweep, loft, etc).  So, the approximation is heavier, and to some extent less accurate, but, yes, sometimes that does cause downstream workflows to succeed on the approximated geometry.  This is also why exporting to STEP to try to determine the parametrization (UV) does not always map to what the surfaces really use.

[TrippyLighting]

@jeff_strater Yep, I know that this is the case since you've explained this many times 😉

I have cleaned up my own modeling workflows it doesn't happen anymore in my models.

But in this case the geometry is so simple that I found it peculiar that this even works.

@Phil.E Thanks! I reorganized the timeline in the model so the sweep is applied before mirroring the object. Then thickening works fine. The culprit is likely if the sweep goes in the + and - direction, instead of just to one side.

[jeff_strater]

"I know that this is the case since you've explained this many times"

true enough.  That was really more for others on the thread, but valid point.  😄

I noticed something really weird with this model.  My usual first approach to a "model won't thicken", or "model won't shell" (same problem), is to look at the curvature.  When I tried to apply a Gaussian curvature analysis to this model, the following happened.  Are others seeing this?  If so... weird.

[chriseder95]

thanks a lot for all the help already guys I will try to recreate the solution to just start the sweep in the center, and then work my way outwards. Ofc before mirroring. 👍 

but seems like there is something else weird on my model, curious to find out more 🤔😁 

thanks 

[TrippyLighting]

LOL, yes, that has caught me off guard so many times...

Go into the Analysis folder in the browser and turn off the section view.

[jeff_strater]

OK, I am really losing my touch today...  D'oh...  Thank you, @TrippyLighting !