I wanted a robust portable workbench that was quick to assemble and dis-assemble, and that I could easily fit in the car. It needed to be light enough for one person to handle, but sturdy enough to carry a vice and a drill press. The challenge was to use hinges for fold-up legs but to make the bench stable at the same time. This was achieved with bolt-on diagonal braces, which attach & detach quickly with engineers bolts and wing nuts. The bench top is 1200mm x 650mm, height is 735mm (to match another table I use). The design is for indoor use (the fixings and boron treated framing timber would have a limited life if left out in the weather)
Step 1: Materials
A half sheet of 18mm plywood (1200 x 1200 x 18mm). 10m total length of 75 x 50 gauged (about 65 x 45mm) boron treated timber. The boron treatment makes it pink. Packet of 10g x100mm self-drilling screws, Jar of 8g x 45mm self-drilling screws, 8 x 100mm x 8mm engineers bolts and wing-nuts. 4 Hinges (about 65mm wide). 8g x38mm wood screws for fixing the hinges.
Step 2: Cut the bench top & shelf
I cut the plywood into a 650 wide 550 wide pieces (1200 long). The smaller piece is the shelf. I used the 75 x 50 timber to support the plywood off the floor. I clamped a ply offcut from another project as a straight edge 'fence' / guide for the circular saw.
Step 3: Cut the top frame
The bench top overhangs the frame by 50mm all around, so the frame will be 1100 x 550mm. I deliberately didn't mitre the corners because some of the hinge screws would have been to close to the mitre. Cut two pieces of 75x50 1100 long & two pieces about 420mm long (so that the width will be 550mm).
Step 4: Assemble the top frame
Pre-drill the 1100mm timbers for two 100mm self-drilling screws. Use the square to set the corners square. Screw the frame together.