Test with joints

If I make from two object one by joining them in Blender and when I export this to an .stl file the item will be printed as seperate objects.  I created a joint with sphere in a cube
So it looks in Cura.

In the view mode-layers  it is clearly to see that the three objects stays seperated.

After about  1:30 hours it went wrong.  I stopped the printing.

 You see that a part was blown of the print by the printheads fan.  It had no support enough. The other hadn't that problem.