topic Re: Rail failing in loft. in Fusion Design, Validate & Document Forum

Rail failing in loft.

stuart_chale — Sun, 03 Aug 2025 03:23:06 GMT

I am trying to loft between 2 sketches and use a rail to adjust one side. I am getting errors "Cannot create surface from selected geometry. Adjust the selection set. And cannot create tool body for loft.

The loft is from the lower airfoil shape to the rear rectangle with an arched top.

The regular loft works but I cant use the line as a rail to adjust the front of the loft.

I am a beginner with Fusion and have not used lofts before.

Thank you

Re: Rail failing in loft.

jeff_strater — Sun, 03 Aug 2025 03:44:39 GMT

please share your model here, so we can take a look at it.

Re: Rail failing in loft.

davebYYPCU — Sun, 03 Aug 2025 08:05:58 GMT

Works for me, but not what I would do.

Might help...

Re: Rail failing in loft.

stuart_chale — Sun, 03 Aug 2025 10:55:49 GMT

Attached is the file I was working with.

I assume it is something to do with the way I drew the rail as the example by Dave below does work.

Appreciate the help. Just trying to learn.

Stuart

Re: Rail failing in loft.

stuart_chale — Sun, 03 Aug 2025 11:00:37 GMT

Appreciate the help. but besides drawing on a different plane I am at a loss to idetify the difference in your model.

My model is listed above.

And if you do have a reccomendation of a better way to model something like this, please share.

Fairly new at Fusion and just trying to learn.

Stuart

Re: Rail failing in loft.

davebYYPCU — Sun, 03 Aug 2025 12:24:33 GMT

I can't explain it. I have almost redrawn your file and still will not work.

Checked that there are no 3d sketches, sketch articles are on the respective sketch planes.

two things, did you import any sketch to this file?

you say - but besides drawing on a different plane what does this mean?

Loft is very finicky, you need to learn to use the Sketch Project tools for efficency.

First sketch must create the profile - tick.

Second sketch - Project the TE of the sketch 1 and build off the purple line.

Rail sketch, Project the LE point, and Project > Intersect the semi-circle. Create the spline snapping to both purple points.

Should work, but I can't get it to work. I can't make it work in the Surface Loft with even last resort trickery.

I am having to presume the tool is failing internally for this set of geometry requests.

Edit, your 4th sketch does work within the Loft rules but created a distortion, so would add another sketch behind it.

Got it, with another go at it, Half in Surface Loft, and then a Mirror. See if it works for you.

For a solid I then got the Boundary Fill.

Might help....

Re: Rail failing in loft.

TrippyLighting — Sun, 03 Aug 2025 13:46:10 GMT

I have looked at your design, and my suggestion would be to start with learning fundamental sketching skills.

This video isn't narrated as the techniques should be self-explanatory. I forgot to turn off sound recording 😉

(view in My Videos)

Re: Rail failing in loft.

stuart_chale — Sun, 03 Aug 2025 15:47:40 GMT

Appreciate the reply. Differnt plane just meant that my drawing was 90 degrees rotated from yours. First sketch was on the XY plane.

My default view has XY on the bottom Yours looks like XZ is on the bottom

Nothing imported

I will take a look at your file.

Thank you

Re: Rail failing in loft.

stuart_chale — Sun, 03 Aug 2025 15:50:01 GMT

Appreciate the video, I will try to follow it and yes I am sure I need to improve my basic sketch skills.

Thank you,

Stuart

Betreff: Rail failing in loft.

wersy — Sun, 03 Aug 2025 18:52:19 GMT

The loft is from the lower airfoil shape to the rear rectangle with an arched
Thank you

What is the wing designed for?
I ask because the trailing edge is very thick.
This causes strong turbulence.

Betreff: Rail failing in loft.

stuart_chale — Sun, 03 Aug 2025 20:52:57 GMT

Not actually a wing but a side force generator (SFG) added to a wing tip. Normally just a flat plate of wood or foam. I wanted to try to 3D print them and the goal is to have one of these above and one below the wing tip hopefully attached with an aluminum or nylon screw. I thought an airfoil shape was worth trying. Once drawn up in fusion it should be easy to try different sizes.

Re: Rail failing in loft.

stuart_chale — Sun, 03 Aug 2025 20:55:18 GMT

Video is helpful. I need to review the projection and interscetion function as well as some of the constraints that I may not have applied properly.

Thank you

Betreff: Rail failing in loft.

wersy — Mon, 04 Aug 2025 11:38:45 GMT

I would advise against printing an SFG.
If only because printed material is very sensitive to heat. It can warp when exposed to sunlight or when left in a hot car.
In addition, your intended profile is much too thick. In any case, only an aerodynamic profile would be used. In such cases, it would be more of a slim NACA profile.
The lateral area should look more like this.

The lateral area increases at the earliest behind the first quarter of the wing. This prevents the flow from breaking off at the outer wing in crosswinds.

In other words, it is easy to make mistakes and worsen the flight characteristics.
Better use a flat plate of wood or foam. It will also be much lighter than anything you print.

Re: Rail failing in loft.

rskrazvan — Sun, 28 Dec 2025 19:57:23 GMT

Hello, i have modified the 15th sketch, i deleted the fit point spline and use instead the control point spline.

Also, i have redone the arc on the sketch14