My usual trick is to use old bearing internal and external races (taper roller, roller or ball race) and place one cut through the race with 1.5mm cut off wheel. This allows some flex in the races allowing easy removal.Dress the cut edges smooth and with a small radius so as to not damage the shaft or housing when installing the new bearing. Also usually weld a couple of small pieces of steel as lugs on the race that are out of the way to facilitate removal once the bearing or seal is installed.