Bathroom remodel - cutting copper in a corner

[TresK3]

Working away at the bathroom remodel, I've discovered that I have to replace some of the old copper DWV pipe and the toilet flange, etc. Apparently electrolysis between the copper and the wire in the concrete under the floor tile left me with a hole the size of a nickle in a 3" elbow.

So... I bought a Bosch oscillating saw to cut the pipe. It works great on most of what I've got, but the 3" DWV pipe is next to a stud, in a wall. I can only access two sides. The blade on the oscillating saw is only 1-3/4" long (strangely enough, that won't cut a 3" pipe, duh!). I found, and ordered, a 4" blade online, only to find it fit the older style of Bosch oscillating tools, but not their new Starlock system. I can't seem to find anything long enough that fits the Bosch tool, nor can I find an adapter for the old style to the new. I can cut around much of the pipe, but there's about an 1" in the back corner that I can't reach. I tried putting a hacksaw blade into a pair of vise grips, but that doesn't seem to work (not enough room to work the blade).

Any suggestions on tools or techniques? I read someone in another board suggesting a wire saw, like used for cutting branches when camping. Has anyone tried anything like that? Would it cut copper?

Thanks

 

[TresK3]

Nevermind... (in my best Roseanne Roseannadanna voice)

I got the three cuts I need to make done, using a combination of the oscillating saw (short blade) and a hand-held hacksaw blade. The trick turned out to be multiple passes with the oscillator to make a really wide saw kerf. That way the hacksaw blade didn't bind. Also, working the hacksaw blade slowly at first, so that it made it's own kerf. That, and a lot of persistence, and pipe came lose. It's still in the wall, mind you - it's binding on something else, but I think that's just a matter of notching out some of the surrounding wood a bit to free it.

Now it's time to sit in front of the fire with something cold and alcoholic.

 

[Highbeam]

I have the 3" copper drain pipes and so far I've been able to reuse it but I have a toilet flange in my future. Hoping that the flange is still good and doesn't need any modifications. On one hand it's kind of cool seeing soldered 3" brass joints but ABS is way more pleasant for me.