Lofting adds more points than necessary that deform the shape.

[maula006]

I just finished drawing up two sketches, each very similar to each other. I am very sure that the sketches have the same number of points and edges. as you can see.

However, I have an issue when lofting...

Instead of the shapes connecting to each other as expected, from point to point, lofting introduces an additional number of points that deform the resulting solid.

Currently, this affects one side of the loft, as you can see below...

While the other side is perfectly fine (notice the number of points).

Can anyone guess why this is happening? I'm not sure if this is something that's my fault or a Fusion 360 limitation.

I've tried remaking the sketches ended up with the same result...

[TrippyLighting]

Can you share the model? (export as .f3d and attach to post)

[maula006]

Sure thing, here you go.

Sketch5 and Sketch 6 are the sketches I want to loft.

(btw, if you're wondering, I tried doing sweeps, but it  doesn't create the shape I wanted.)

[TrippyLighting · Accepted solution]

This is a bug. Fusion 360 does not get the point mapping correctly, and quite horribly so.

Workaround with surface lofty is attached.

@Phil.E Can you check this out please?

[davebYYPCU]

Yep, I have seen the mapping handle problems more recently than the old days, what's worse is when the yellow self intersection routine jumps out at you, there are NO mapping handles to adjust.

[maula006]

I see... I was afraid you would've said that.
I did mess around with surface lofts and that did work, but I was hoping to make my history a little neater.
I'll check out the file you made.

Thanks for the help!

[jeff_strater]

@maula006   One correction to:  "Fusion 360 does not get the point mapping correctly".  That should read "Fusion 360 does not get the default point mapping correctly".  Point mapping in loft is a fairly complex geometry analysis task, and yes, sometimes the initial mapping is incorrect.  Fusion comes up with an initial guess, but that point mapping is just an initial guess.  Those white dots can be dragged to change the point mapping.  In this case, it is a pretty simple edit to get to the state I think you are after:

I've shared that model as the "(js1)" version.

Alternatively, you can add rails to force points to be mapped.  That is pretty simple as well.  Add a new sketch, turn on 3D snapping, and add a single line from the problem points in the design:

That makes the loft succeed without any point mapping dragging:

I've added that as the "(js2)" version

So, now you have a couple more options.