ok So here is the deal. I have the 2 elements marked in blue which I want to align. I tried to use a column between them as a guide on which to create a tangent joint or something like this. The idea was to connect somehow the side surface of the column to the cylinder and a point on the other side of the elements. But I'm just not that good yet with Fusion. And not having even a single flat surface doesn't help either. What would you do to achieve the result in the last image with high accuracy? Right now they are just positioned by an eye as they are on the last image. Maybe I don't need to the column, I just need to position them accurately in space. The left and the right side are different on the bottom, so it's not just like a mirrored part.
Hard to find a reference for a joint when there is no flat surface
You can create joint origins by adding a new sketch with points to the component or by using one of the sketches used to create the component. For a new sketch in each component, project the body. Draw a line tangent to the projected curves. You can use the end points of the line, or put a point at the midpoint, to use as joint origins.
If these are going to rotate around the small hole, then I'd use the center of the holes as joint origins between each component and the component they will rotate around. Use the line drawn previously to calculate the angle when they are aligned.
ETFrench
ok, I think I found a solution. I made a sketch with 2 extruded cylinders which I used with a concentric joint. The left one was rotated around the cylinder on 45* from the original position on which it was modeled. The right one was 135*. They can be moved around by the sketch.
