Jointing and planing SYP 2x4s for a workbench top?

I recently made a workbence top out of 2×6s myself using my tablesaw. I resawed each 2×6 in half and then trued up each edge on the tablesaw all to the same dimension (as I recall about 1-5/8×2-1/2). I then glued these up using cauls. The first glue up was two each (1-2, 3-4, 5-6, ....) then I doubled those up (1-4, 5-8,...) until I had them all glued. I paid real close attention ensuring at least one side (the top) glued up as flat/true as I could get it. To finish it I stuck some self-adhesive sandpaper to one side of a length of 2×4 (that I trued up on theTS) that was a bit longer than the top was wide. I then did the pencil squiggle thing, marking all over the top, and then sanded until the lines were all gone. By using the 2×4 sanding block longer than the overall width, it sanded it down true/flat across the whole length.

If your surface after gluing is too much out of flat/true to go directly to sandpaper, you could use a joining plane first.

-- Shameless - Winner of two Stumpy Nubs Awards

You will have to joint the boards. 2×4s come with a rounded edge and are not ready to glue. You can do that pretty easily with a jointer plane. Once you have a good edge, you can glue them together in groups of 3 or 4. Once its dry, you again use your hand plane jointer to flatten the surface. You repeat for 2 or 3 groups and then glue these together and do a final planing.

-- Yves