In the attached file is two examples of a sheetmetal item that has a cutout with some upturned flanges. I've shown two methods of creating the cutout. The top one being a rectangle, then some fillets, then the flanges. As you can see there is no relief and is of no use. The loower one skips the fillet stage by having the fillets as part of the extruded cut, then the flanges are applied and I get the result that I am after and would have expected with the top one too... so can anyone shed some light on to what is going on?