Hi, I've been a CATIA V5 user for 10 years and recently started to use SolidWorks. Most of the stuff I've had no issues with but I'm trying to get to grips with some of the differences in the way that the 2 packages work. I've recently hit a problem trying to run a large fillet around the edge highlighted below. The height between the 2 surfaces is 1mm and I want to run a 6mm radius in the bottom. In CATIA I would usually model the cut as a negative entity, add the fillet at that level and remove the cut from the solid body leaving the feature that I want. If I was to do it as below however, I could simply select the fillet command, and then select 'keep edges' and click on the edges that I want to remain. This would put a 6mm radius in the bottom to simulate using a 12mm ball nose cutter without touching the edges next to it. I've tried to use the 'Keep edge' feature and that doesn't work and if I use the 'Keep surface' feature it adds the fillet but moves the edges inboard as per the second picture.

Can somebody please tell me what I'm missing?

Thanks