Continued demo on the bathroom.
I've really been fretting about the wall by the shower (noted earlier). I started to demo it and it was pulling the shower wall away. So, my plan was to cut the backer board.
Well, the stud was a bit further back than I anticipated but it actually was ok because the shower tile came off much easier than the wall tile. I think the backer board is OK.
I went to lowe's to get a diamond blade as zikzak suggested but I couldn't stomach the price. I saw a grinder blade that said it was for cement board and it was only $3.00 so I got it.
First, though, I thought I would try an old hardi-blade. Sparks went a flyin' and I was pretty sure I would burn the house down if I continued with it. So, I put on the grinder blade. Worked like a charm. The top and bottom I just used a scraper. I'm super pleased with the result (2nd pic). Nice straight line. On a stud. All I need to do is sister up that stud for the new backer board.
All the demo is done except for a part of the floor in front of the shower. I'll wait on that until I'm ready to put down the floor backer board.
I think I"m pretty much done until a plumber comes to rough in the plumbing for the tub.
All in all this gave me some renewed hope. Getting that board cut away from the shower was a major obstacle (for me anyway). I might be able to do this after all.
Kinda hard to see but here's that cut I made.