28. Dado the boards

Using the T-square to keep the board straight, cut the groove.  To do this, cut on the line as you push the board out - then shift the board over a bit before you come back so you cut another bit out on the return.  This push and pull cut should be seamless.

These photos show you how the groove is growing.  Top photo show the push out - bottom shows a pull back.  I probably had to do this a dozen times or so.

NOTE:  I REALLY REALLY should have on safety glasses!  I could feel the sawdust in my eyes and it wasn't pleasant!