> Does exist some limitations or precautions with these sorts of auto Intersect surfaces?
> MoI manage them without restrictions?

These are usually called "self-intersections". These types of surfaces will cause problems in several areas, especially things involving surface intersections (which includes trim, booleans, fillets). It creates a problem in the topology of an object, where one 3D point location belongs to multiple different spots on the surface - this can mess up several algorithms.

So it is best to try and avoid making those types of surfaces if you want to do any more advanced operations to them later on.


> When you move a circle by one unordinary point to the intersections
> a,b,c there is no snaping, but if you move this same circle by its "Quadran"
> there is snaping on "warm point" a,b,c !
> Is that normal? :)

It's normal - when you drag an object, it will snap the base point of the drag to either the end, mid, quadrant, or (for solids) the center points just of that object. Intersections are not included because those are not points that sort of "only belong" to the individual object. It would look kind of strange for instance while you were dragging the object around and the "Int" label showed up while you were dragging it. However, having "end, mid, quadrant, or center" show up while you are dragging makes more sense I thought.

Just as you realized, you can use Transform/Move to lock the base point on the intersection if you need to.

- Michael