Drill through a cast iron sink?

Question

I have recently upgraded my counter tops because I added a dishwasher (had to move/add 10 1/2"). I kept my original sink which is a old cast iron beauty. I already have a nice faucet with a separate sprayer. So my sinks four holes are all occupied. So I have to fix my vent/breather for the dishwasher somewhere. I know i can go through the counter top but would like to avoid it.

Is it possible to drill through this sink? I am afraid to start because there is no turning back once I do. And if so what kind of bit is recommended?

Answer 1

There is a special kind of cup bit made to do this job, WARNING IT IS VERY HARD AND MAY TAKE AN HOUR OF DRILLING TO COMPLETE HOLE! Just go to your nearest plumbing supply house and tell the counter person your intentions, they'll help no problem; except for making that hole

Answer 2

You can drill for the air gap (that's what they call the vent).  Use a hole saw at a slow speed.  It will trash the hole saw, but it will get the job done.  I had to do that in my sink too.

Answer 3

Do you know that you need the vent?  We updated our kitchen last year and our plumber told us there was no need for these on the newer dishwashers.  We haven't had a problem and it's been run almost daily for the past nine months.

Answer 4

the vent breather from the dishwasher loops over the top of the machine, and below the counter top, then goes into the p-trap under the sink.  There is a fitting for this.  You do not drill a hole into the sink.