This was a pretty straightfoward part of the job. The only trick was getting a snug fit and centering the groove perfectly.
You see, I had foolishly milled the breadboard ends to exact thickness, rather than oversizing them a hair. This meant I had to be spot on!
How could I perfectly center the groove?
The trick turned out to be to get close.
Rather than aim for perfection, I got as close as possible. Then with each pass on the table saw, I ran each piece through twice (once on one side, and once on the other). Flipping the side of the piece which was against the fence made up for any imperfections. Than I simple moved the fence one way or the other slowly until I had the fit I wanted!
I also found some termite work in one piece.
-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν