What is a workbench?
A woodworker's workbench isn't a table, it's a work-holding system. It's not something you set things on top of, it's a tool that holds your work. Where a worktable might have a machinist's vise bolted to its top, a woodworker's bench is built to accommodate a number of different workholding mechanisms, such as bench dogs, planing stops, hold fasts, or board jacks, and will usually have one more woodworker's vises integrated into its structure.
A workbench needs to be heavy enough that it doesn't move under you while you're working, and stiff enough that it doesn't rack itself to pieces under the forces that will be placed upon it. It doesn't take many hours of planing a board or hammering a chisel for a worktable made of nailed 2x4s to come apart. Traditional bench designs use mortise-and-tenon joinery, which is strong and rigid, but not really suited for a novice woodworker who doesn't already have a bench.
This instructable shows how to build, with basic tools and readily-available lumber, a bench that provides most of the function of a traditional woodworker's workbench. I began with a design by Asa Christiana that was featured in the second season of finewoodworking.com's video series Getting Started in Woodworking. The project plans are available on their website.
Christiana's design was a simplification of a bench from Sam Allen's book ''Making Workbenches''.
The bench I will be describing differs from both of these in a couple of areas, the most significant of which is the top. Allen's top was made from three layers of 3/4" medium density fiberboard (MDF), topped and edged with 1/4" hardboard. Christiana's top was just two layers of 3/4" MDF. My top is two layers of 3/4" MDF edged with 1/2" oak and topped by a 1-1/2" thick edge-glued oak Ikea countertop. My top is more expensive in both time and money than either Christiana's or Allen's. If you're looking to build something fast and cheap, I'd recommend Allen's approach over Christiana's. The hardboard significantly increases the durability of the top.
The essence of the design is a joinery system using threaded rod that provides a great deal of strength and rigidity. The base is formed with 4x4 legs and 2x4 stretchers, connected with dowels and threaded truss rods. As screws are tightened down at each end of the rods, the structure is pulled together forming a rigid unit.
I am new to woodworking. I'm learning as I go along, and I'm documenting as I learn, in the hope of being helpful to other novices. On the range from slap-dash to deliberate, my method is definitely on the deliberate side. If you have enough experience to be confident in using techniques that are more time-efficient, go for it. The techniques I'm using are those I thought least likely to go wrong, not those that would produce a product in the shortest time or at the lowest cost. You'll notice that I made a number of mistakes, spent considerable time on work I later determined to be unnecessary, and in a number of cases I used different techniques at the end than I did at the beginning. These are all the result of learning. I thought it would be better to demonstrate how I made errors, and how I corrected them, than to provide a set of instructions that presented the false impression that everything went together perfectly.