I just made 2 cuts thru 4" cast iron soil pipe and 2 thru 2". I used a 4"
Makita side arm grinder on recommendation of a couple of plumbers. I was
surprised at how quickly it went. Started with a used cheap wheel and pretty
well used it up in the process. I tried a DeWalt Recip. saw with a new
hacksaw blade first and it just made a shinny place on the pipe.

Walt Conner

I need to a cut a 4" cast iron sewer line