Create flat cut pattern from loft surface

[TheTrevisans]

Hello, 

I am trying to flatten/unwrap  a curved surface which was created with a loft, and then combined (cut) with another shape.

 

Basically this is a fairing on a model airplane. It joins the engine cowling to the wing, and it will be made out of balsa wood. I would usually make something like this using a supporting structure, and then "planking" strips of balsa on top, but I recently found online this picture and I am trying to find a reasonable way to do something similar..

 

 

 

I have searched the forums and tried to use mesh mixer, I managed to get a flat surface but, unless I'm missing something, there is no option to set a number of cuts that will make this work before unwrapping. I thought about cutting the initial shape in thin slices before exporting and unwrapping, and then import back in fusion or another software and join them back together, but it becomes so much work that is not worth the effort (as there are several other surfaces to cover in the same way), and I'm not even sure it would work as meshmixer will distort the slices a little anyway.

I attached the surface if it is of any help.

Thanks at least for reading all this!

Carlo

[TrippyLighting]

Any non-developable surface will be "distorted" by unwrapping it.

Fusion 360 does not have a built-in solution for UV-Unwrapping. ExactFlat might be a possible solution but it's pricey.

[davebYYPCU]

Can be done in MeshMixer, ok for woodworking.

Save the body as STL, import to MeshMixer, 

use the Unwrap function.  

Save the flatpattern as STL and import to Fusion.

Convert the mesh to something usable, by tracing or Section Sketch, etc.

I don't know why the mesh body is in error.

Might help....

[laughingcreek]

I have done this sort of thing with a fusion to pepekura workflow numerus times.  it helps to split the face along the lines you want pepekura to to use before exporting.

[TheTrevisans]

First of all thanks for coming to the rescue!

Let's say a small amount of distortion is acceptable, the balsa wood is so soft and can be sanded, or just pressed to overcome small imperfections.. but the way meshmixer produces the surface in one single shape, it will give me some section of a cone, once made out of balsa. 

So trying to retain that convex "slope", I tried with pre-cutting the solid in Fusion, 

 I made a patch, extruded (0.5mm, just to be easier to work with), and then used the circular pattern to path on the top border.

I Split the surface with my freshly created solids, and got this: 

Now its not easy to see but they aren't single lines, there is a small area 0.5mm wide in between. I deleted all these (the narrow surfaces), before exporting the stl to meshmixer. Once unwrapped it gave me something that at least looks like what I wanted to achieve. The idea is that at least being now curved stripes, the errors once unwrapped should be smaller (am I making any sense?). I will test it on paper and let you know!