Hi Pilou, it's hard to explain, it is sort of how Rail revolve works.

One part is that rail revolve needs to combine the 2 curves together into a surface. So it is more predictable to position the rail curve so that it is at one edge or at one side of the profile curve rather than running right down the middle of it.

Down the middle would be more how sweep works, which kind of guides the profiles along the path. In rail revolve, the path becomes more directly a part of the surface, it is almost like the path and the profile are multiplied together more directly in a certain sense.

Then the other part is that rail revolve is also a type of revolve which applies scaling outward from the central axis. If your profile curve is sort of slanted with respect to the axis instead of straight in line with the axis, you will also possibly get some less predictable scaling results. So to get more predictable results, place things more like this:



But still since it involves rotation and scaling, you will get different sized results along the closer or farther legs of the rectangle. You probably want to use loft for this like you show, to get an even shape without scaling.

- Michael

Your exemple works only if the Rectangle is a "square" else sides are deformed :)

The only thing curious was that the initial position of the profil section was changed and deformed itself :)
Despite ot that Rail Revolve is a very funny and useful function :)

> Your exemple works only if the Rectangle is a "square" else sides are deformed :)

Yeah, there isn't any way to avoid that type of deformation in rail revolve because it does a part of its work by a scale outward from the axis line. To place the profile along the farther point of the rectangle it is scaled to get there and scaling grows the entire shape.

- Michael