See our projects section on plumbing in a dishwasher and washing machine. You will see a strap on boss being used and this can be done with cast iron also. You will however need a very good drill with some expensive hole cutting drill bits. It is very often easier to replace the cast pipe with plastic.
IT WOULD HAVE TO BE AN HSS OR CARBIDE FINE TOOTHED CUTTING TOOL.
CUTTING AT A CONSTANT LOW TO MEDIUM SPEED AND STEADY MEDIUM PRESSURE I THINK YOU WILL BE SUCCESSFULL.
(CUT DRY, DONT USE LUBRICANT OR WATER TO COOL)
(COMPRESSED AIR CAN BE USED TO COOL)
MOST BREAKAGES OCCUR THROUGH EXCESSIVE VIBRATION OR JARRING. SO TRY HARD TO AVOID BOTH.
BECAUSE THE SURFACE BEING CUT IS CYLINDRICAL AND THE END OF THE CUTTER IS FLAT, THE VERTICAL CENTRE OF THE HOLE WILL BREAK THROUGH FIRST AND THE SIDES LAST, SO TRY TO MAINTAIN GOOD DRILL SQUARENESS TO PIPE.
ANOTHER POINT TO WATCH OUT FOR IS WHEN CUTTER IS BREAKING THROUGH. TRY TO PREVENT THE DRILL KICKING AND BITING IN.