Loft issue - Surfaces don't align

[ekalyvio]

I am trying to create the elevator pitch trim of a model airplane (tail).

I create 2 different loft surfaces (just for now - I will use solids later and cut them out). These surfaces are one inside the other. They don't seem to align correctly after creation and they create some kind of a seam between them... This seam is only on the middle on the surface and the start/end profiles don't have it.

Anyone having any idea what is happening and has that bump on the middle of the surface instead of just touching on the inside? There should be only a single touch point with the surface...

I attach the .f3d file in case it is needed.

[jeff_strater]

That is not a seam.  The loft surface is fine.  That is your cylinder surface bleeding through the loft surface.

with cylinder visible:

with cylinder invisible:

It may just be a graphics artifact, and the surfaces really are tangent.  It looks a bit like z-fighting to me, because it does vary with the camera angle.

[jeff_strater · Accepted solution]

On second thought, maybe the surfaces are a bit inter-penetrating.  I added a few rail curves, and the issue seems to go away:

model is attached

[ekalyvio]

Oh, yes!!! It seems like they cut out perfectly horizontally when using solids apart from the surfaces that left behind on the small circle. I guess that this circle needs rail lines too...

Would you mind sharing how you created the other 4 rail lines without creating a new offset plane  and then doing some kind of intersection of the circles to this offset plane?

I had tried to do something like that but it drove me crazy. Functions on the Project/Include menu don't seem to do something like that. I seen that you somehow created the lines (blue) from the intersection of the circles with the horizontal lines.

[ekalyvio]

Ah... never mind.

I found a very nice tutorial on internet that helped me understand how to create a 3D sketch!

https://www.youtube.com/watch?v=qGQgMADxoFU&t=46s 

Thanks!