Cutting 3" pvc toilet pipe from the inside....Really

Hey All, I'm new here and could use some advice. I'm doing a bathroom remodel and am almost done. Problem is that i need to lower my toilet flange about 3/8 of an inch. My house is ranch style with a crawl space, a very short crawl space. Cutting the pipe from below would mean cutting copper water pipes to get to waste line. Here's my question, is there a cutter that attaches to a drill that could be used from inside the pipe to cut it? Any and all  suggestions are greatly appreciated. Thanks, Topher 11 

I'd reach for my trusty dremel tool and put in a cut off blade.  The speed is high enough and the forces low enough to make it more practical to hold steady.

I don't know of the equivalent, scaled up in size to fit into the chuck of a standard drill.  The larger diameter, in my opinion, will be more likely to get out of control and start running in circles inside the 3" pipe.

actually my man

what you can do is DONT cut it 3/8" shorter

actually cut it a couple inches shorter and use an extending piece to make up the difference you really need

the bottom line is if you cant cut out exactly what you need

then give yourself a whole new startign point

cut it WAY down, and then add to it.

At least this way you can actually TEST the fitting and its length before soldering it back in place

We need more information...

What has changed that is causing your problem.?

Other then just being too high what seems to be causing it.?

1. Pipe itself is too high.? Even altering the flange ( maybe getting one with a smaller lip) will not work.? 

2. Pipe seems to be low enough but, the flange will not seat low enough to rest on the top of the floor.? Maybe a flange with a smaller lip or altering the one you have may work.?

If not, a picture would help........

I think the best thing you can do is find out why you need to raise your flange and do something there to compensate. A Dremmel is the only thing I can think of for cutting inside a 3" PVC pipe other than a small, sharp and sturdy hacksaw.