Copper toilet flange into cast iron pipe issue

sawcut

Yes, just start at the top of the pipe and cut a "spiral" down to the flange, and then just cut around the pipe using the flange as a guide. When you get back to your starting point the piece will lift off. You can hold the saw at any angle which is convenient while making the cut. All that matters is that the top of the pipe be FAIRLY straight, not necessarily perfectly even.

IMO: Taking out the copper from the CI hub and putting in PVC with a donut would be reasonable. I'd not expect the donut to leak if you clean out the hub thoroughly and use a donut that fits (they come in different sizes as not all cast iron is the same).

But since you already did the floor, and bought the copper flange, why not just trim the pipe and solder it on? You can probably trim the pipe with a normal hacksaw with the blade turned 90 deg--sort of spiral down, and clean it up with a file. As for the soldering (sweating), if you clean everything up to nice shiny metal, and flux it, and the fitup is decent, you should be able to work around it, heating from the inside. You will need a substantial torch, acetylene or propane with a "turbo" tip of the right size.

Thanks for the replies but it's already done...see two posts up