I was not clear perhaps. Using the thin blade on the grinder to actually cut into the side of the pipe was my intention. I post this just to avoid someone just grinding down the pipe.


I also was unaware that you were on concrete. This is much better in general overall with an old toilet that has been seal leaking. If the old anchors for the toilet were good. You may not have to really anchor the flange itself that heavily.


Actually what may be easier overall after I gave it some thought. There is a brass flange that is designed to go on over that cast iron pipe that is above the concrete I believe. The id of the flange is the same as the od of the cast iron pipe. A seal of silicone on the flange to the pipe would be good enough. I believe I have seen them but never used them.


Remember I am not a tradesman in this area. At this point I would ask any older plumber although the newer guys are probably familiar with this as well. It almost sounds like in the original installation it was just left out. You may still be almost forced to use the plastic one. As the bottom height of the flange almost should match the tile height. Or the flange may need a shim itself.


Not being a professional I am not certain of the compression range of the wax seal .Double wax sealing though is not uncommon either. Lay your level across the tile and mention if there is still some cast iron pipe above the edge of the level. That add on flange for cast Iron is probably available in plastic as well.


I better stop now before I give you a stroke. There is a possibility that whoever installed that toilet itself did not know what they were doing. Odd that I have not done that much work on cast iron drainage systems. Other than cutting enterance points to facilitate Ts and Ys. Incidentally I have no use for long term durability of foam seals. There is no adhesive factor probably in comparison to a wax seal. Plus over time the foam probably relaxes. Or breaks down. On the other hand a wax seal may not stand substantial movement.

Being 78 years old. I may even be getting a little forgetful. I have lived with women so long now I almost forget what freedom was like.