I have a rough in bathroom that was done in 1968 for the homeowners to finish. Cast iron pipes for shower and toilet are about 4 in. out of floor. How do I go about cutting them to install a toilet and a shower? To be flush with the concrete floor.
Usually, the easiest way to cut cast iron pipe is with a snap cutter, but I don't think you could cut it completely flush with one. A sawzall with a long diamond tip blade might work for you. A diamond wheel in an angle grinder is another possibility. Alternatively, you could frame a wood floor to the height of your pipes.
If they really need to be flush, I'd recommend using a 4½" angle grinder. Cut the pipe close to the concrete with an aluminum oxide abrasive cut off wheel. Spring for the good ones, and get an extra. Finish the job with a flap disc, which will allow you to get in nice and close with good control. Your application won't require anything finer than 40Grit, which will give you a decent rate of material removal. Use a type 27 zirconia alumina disc. And PLEASE USE EYE PROTECTION.
Had a half bath where the 61 yr. old commode had a very slow constant leak/refill issue. Replaced all the internal parts possible, some twice. When I pulled it up to replace wax seal, noticed that the cast iron pipe was rigid and uneven/wavy with 1/2 inch or more differences in height. Took my angle grinderwith 40 grit ferrous metal cutter to it, after attempt with oscillating tool with metal cutting attachment. In 45 minutes, it wore out cutting just two inches. The angle cutter took 10 minutes, never wore out blade. *SPARKS! Tip: because of limited space, location, and sparks, I soaked old, large work towels dripping wet. I spread them out covering newly installed beadboard, baseboards, and flooring. I stuffed pipe to prevent metal from going down drain. IMPORTANTKeep a large bucket of water and a fire extinguisher within arms reach. I used nearly all the water to cool the wet towel in pipe, and rewet others. *There is alot of "dust", but a lot it got caught up in the towels. Still had to clean up from ceiling down. Use rags you can throw away, there will be dirty greasy wax in the "dust". Use the widely known name brand, blue grease cutting dish soap full strength on wet disposable rags. Don't bother rinsing out, gets gummy and rusty, just throw away. Will clean up easier and faster.