Here's a simple bench you can build for under $60 using only dimensional lumber and plywood. If you build your top so it is 24" wide, then you'll have plenty of plywood left over from the 8' sheet which you can use to build an extension leaf.
The torsion box top allows you to mount all sorts of fixtures and hold them in place. I am able to use my fixturing clamps, and I've also mounted a general purpose bench to a plate which allows me to move it anywhere on the bench, or to the extension leaf.
There's a shelf on the bottom that allows you to store tools, which is nice because the bench itself is rather lightweight and it adds a bit of heft to the bench.
I created the model for my bench in Sketchup, then worked out the cut list. I used Inkscape for the sheet goods, and used a spreadsheet for the cross cuts. Planning every cut like this is pretty time consuming, but it is well worth it since it allows you to make the best use of your material.
The top is made from a single sheet of plywood. I had the home store cut it down for me so I could fit it in my station wagon. I then used my table saw to get the final widths for the top pieces, and the slats that would make up the torsion box top.
The frame is constructed using dimensional lumber that has the rounded edges milled off. The 2x4's become 1 ½" x 3 ½" and the 2x6's become 1 ½" x 5 ½“. From here on out, it's just crosscuts.
Everything is assembled using pocket screws and carriage bolts. The individual components are held together with glue and pocket screws, and the components are held together with carriage bolts. The nice thing about using carriage bolts is that they can be tightened over time as the become loose.
For the extension leaf, I added the ability for it to be mounted to the end of the workbench by using some old gas pipe. I wanted to store the pipes in the extension leaf, in case I wanted to add another extension leaf. In practice, this is not the best design decision because only half of the leaf is supported when it is place. The other half needs to be supported by a 2x4 that rests on the ground. This does work, but it is not as convenient simply being able to pull out the extension arms and attach the leaf.
The plans for the torsion box workbench consist of Sketchup models, a drawing for breaking down the sheet of plywood and a cut list.
|Torsion Box Top (.svg)||Download|
|Torsion Box Cuts (.xlsx)||Download|