I tried 2-sided cutting on 4 axis mill this time, with a block of mahogany wood.
I didn’t have a round bit at time, so a spherical concave surface is cut into steps by the flat bit. I had to sand it manually later.
Once the roughing pass finished cutting the surface and notches, I stopped the operation as I realised that it’s just cutting tabs. Tabs were simple to take care of manually on the sander belt.