Loft Issue depending on which profile is profile 1

[robertASTUP]

I am trying to make a model with a loft that goes between a elliptical face and a rounded rectangular face but I am finding that, depending on which profile I chose as profile 1, the model is noticably different. See the attached screenshots showing the curvature map for each:

Profile 1 - Ellipse FaceProfile 1 - Rounded Square Face

It is clear that when the elliptical face is used as the first profile, the model is asymmetric whereas when the first profile is the rectangular face, the model is symmetrical. Is this a bug in Fusion or is there supposed to be a fundamental difference between these two?

Thanks

Robert

[TheCADWhisperer]

@robertASTUP 

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

I would probably add some guide curves.

Edit: Also, I probably would not use sketch Profile.

[johnsonshiue]

Hi! I believe this could be due to lack of specific mapping requirements. As a result, Fusion has to figure out how to map an ellipse to the rounded rectangle or vice versa. The two can lead to different results. Adding more guide rails may help yield more consistent results.

Many thanks!

[robertASTUP]

Hi,

Thanks for your response. I have attached the f3ds for the more symmetrical and the more asymmetrical models.

Do you know what settings I need to set for the loft to be consistent regardless of which profile is set as profile 1?

Many thanks for your help

Robert

[TheCADWhisperer · Accepted solution]

@robertASTUP 

I attached two examples.

In both examples I used body faces rather than sketch profiles for the Loft.

In on example I used guide curve Rails front and back (you could also add Rails on left and right for more control).

You can make the Rails whatever curves you want to control your Loft shape, my curves were just examples.

In the other example I used Weighted Tangencies...

You can set the Tangency Weight for each Tangent.

[johnsonshiue]

Hi! I added a few logical guide rails to the symmetric model. Here is the proof that the added rails help making the resultant Loft geometry consistent regardless of profile picking order. They are almost identical.

Many thanks!