Having the dreaded “lofted body has self intersection in at least one of its geometries“ error and Incant fix it.

The bizarre thing is that it works in particular direction but not in the reverse but this conflicts in the way I need to complete the object.

So to explain:

I need to construct a model which is essentially a row of horseshoe shaped sketches ( five) all with the same flat base on a plane but varying heights/and shaped curves. They are not symmetric and to define the curves I have constructed points on a vertical line with cross bars and marked points on the cross bars.

I then joined the points with the spline tool. I repeated this process for each of the five curves then deleted all the framework lines.

I then transform the sketches to the distances needed to turn it into a 3d model.

I then try to use the loft tool to join each sketch curve to the next and complete the model as 3D

But this is where my problems start.

I have tried to loft all five sketches together. I have tried to loft them as single segments between pairs of sketches.

Lofting them as single segments between sketches.

Some will loft in one direction only. No intersect error if I loft say upper one down to lower one or vice verse. but if I go in the opposite direction it fails. Trouble is some fail in both directions or fail when on is already part of the solid but is OK if it’s just a sketch. Some will have combinations of problems that mean it will work to do partial solidification but not the whole thing.

But that’s all not much help because lofting each pair separately generates a series of straight surface blocks. I need a smooth flowing surface on the whole model.

For that I think I need to loft all sketches together in the one loft.

But that fails every time with the same error.

I have to admit I cannot understand how what are essentially distorted semicircles could intersect between two sketches anyway. clearly they don’t truely have any points or planes that intersect.

I suspected maybe the multiple spline points may be an issue and somehow it confuses points. tried doing each curve with same number of spline points in basically similar places but that didn’t seem to change anything ( except degrade the accuracy of my curves)

Any hints on how to use the loft with complex shapes.