Lower Sink Part 2

I would like to restart a question by plumbob from a month ago. I'm also remodeling the kitchen and the new, undermount sink drain is much lower than the existing sink drain. In fact, the drains will be even with the existing wall drain, so from the prior thread "major surgery" is called for. I've got the cabinets off the wall, anyway, so I expect to find two 1 1/2" branches leading to sanitary T's at the vertical drain. The plumbing is all PVC and about 20 years old. My question is, how do you cut new fittings into an existing, vertical DWV line? Are there "slip" style couplings I can get, or do I need to use the neoprene couplers with pipe clamps? BTW, I've got an engineering background and have done some serious "plumbing" in chemical plants, as well as a large number of home improvement projects, BUT... I want to get this right or have someone do it for me (unfortunately, my calls to the tradespeople around here are rarely returned--way too much business and way to few suppliers!). I'll appreciate any and all advice.

Frank

Lower Sink Drain

Can you post a picture, Frank?

They make a repair coupling that does not have the typical rib in the middle. This means that you can slide it to one side, place the other piece in alignment, then slide it down to cover both parts. The trick, and it is a trick, is to do all of this before the glue sets up and you can't move it at all. Sometimes there is enough play where you can spread the pipes apart enough to put in a "normal" coupler. The easiest way is probably to use a Fernco. Run this by one of the pros here to verify first, though. Depends partly on what the local codes will allow.