Now for the bases.
Capture a footprint.
Ash in the foreground and Red Oak behind that.
The Oak is cupped. Begin by face jointing, crown up
If the crown (peak) is down, the board will rock as you feed it through and you won't get a good flat reference side.
Now plane it, again crown up.
The board is perfectly flat.
Now you can joint the edges.
The Ash was cupped also, but at 2 inches thick, I was sure the surface planer's stock-feed rollers would not
artificially flatten the board, as it would with the thinner Oak boards. Meaning, the feed rollers press down pretty firmly and temporarily flatten a board, before the cutters even contact the board. As the board exits the planer, it springs back into the cupped shape. Not so, for this thick Ash. Once you get a flat reference surface, you can joint the edges.
Joint the edges.
Re-Saw the Ash.
I'm ready for panel glue-up, but I'm out of time for today.