Thanks GPW. I read that. I think the problem was that I started the kerf at the bottom where all the stress was at. Thinking about it now I think I should of started at the top or let the foam relax and started over. I still like the idea of two sheets of 1" with the kerfs towards the center. That would make for less work filling grooves, and sanding.
I just got done making a hot wire jig that will cut five 3/4" inch deep grooves at a time. Gave it a test on a piece of scrap and I think it is going to work great.
These jigs take a bit of time to set up, but are easy to do and sure speed things up in the long run.......
I have a tight radius on the back that I am a bit concerned about now.
I have a couple ideas for that too.....