I wanted to build a very strong workbench for my add-on shop. I also was going to add a middle support for workbench if necessary. Turns out that one was not needed.
Step 1: 2x4s
I bought 2x4s from one of the big box stores - not the best stuff but my planer would make a good flat surface. My planned work area was just over 8ft long and just at 20 inches wide so not a lot of cutting.
My planer is only 12 inch wide so I had to build the bench in 2 pieces.
Step 3: Square, Glue, Screw
I used wood glue and decking screws to attach each 2x4 to the next 2x4. I got things as square as I could knowing that the planer would make a nice flat bench.
Step 4: Both Pieces Built - Now to the Planer
Both pieces of bench top done, to the planer. Final thickness was just under 3 1/2 inches. I only ran each piece through the planer 5-6 times which made the surface nice and flat.
Step 5: Secure Both Bench Top Pieces Together.
Both pieces done, I attached the two tops together with 2x4s across both ends.
Step 6: With a Little Help From My Friends
My son and I then carried the bench - now connected and in one piece - and placed it on the wall supports.
Step 7: Finished!
I finished things with a couple of coats of danish oil. The bench is so sturdy that a middle support wasn't needed but can always be added later.