Multi-Depth: this parameter is important here, and it is important whenever you need to remove a lot of material, here you specify how many material you want remove per pass, if you insert 2mm of Cut Z and 0,5mm of Multi-Depth FlatCAM generate 4 passes of 0,5mm. A problem when you remove a frame is that at the end of the cut, the material can. FlatCAM started as an isolation and drilling tool. FlatCAM beta (the one I've actually grew) is meant to be a platform on which all sort of tools can be built, one on which Isolation is just a tool out of many. Soon, the drilling will be moved too in it's own Tool.