I slowed it down a bit for a Roller F and the fillet on the semicircle came out much nicer, still not perfect but fine by me.
Side effect of using big nozzles- My parts are very overweight. Corner block weighing in at 69g (118%) and Roller F is 116g (129%). Good new for durability but I might need another spool of filament. I’m guessing my perimeters are too thick (3 perimiters w/.4 nozzle would be about 1.5mm vs 2 rings with ~1mm extrusion width is 2mm.) I don’t think I want to go down to a single super wide perimeter so I’ll just say screw it.
What is the real dimension on the hole you asked about?