To place an object, it appears that Slic3r v1.2.9 is minimizing the distance from the centre in the X and Y axes? That isn't the best strategy for a Delta... worst case, it leaves corners of the object extending outside the bed. This is really irritating because Slic3r doesn't allow me to manually position objects.
In my view, for a Delta, the object should be placed such that the smallest circle that contains all of the object is located at 0,0.
As a workaround, rotating the object around the Z axis changes its X & Y lengths, so it changes the placement in Slic3r... by rotating this object by 60 degrees, I can make Slic3r fit it on the bed.
Issue report at [
github.com]