Sam Allen also did a workbench book worth checking out.
If you want to go through a semi-over-the-top woodworker bench and the process of making it, with screws ups and the way I fixed them - or made some into "features" check out Das Bench - all 32 pages about it.
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you can check out what is now a big assembly bench that served as the only workbench for a couple of years - 1 1/8" ply, 2x4s and a piece of 1/4" melamine.
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't make it air craft carrier deck BIG - 24" wide is plenty wide for most things and 6 feet long will probably work for just about anything you want to do. If you intend to use it to work with hand tools - planing, edge joining, cutting dovetails, mortises etc. and handsawing up a storm keep it low. Rule of thumb seems to be to stand up straight - hands at your side, palms to the rear. Bend your wrist so your palm is down and paralleling the floor-that's your bench \ height. Seems low but much of hand work involves using your body weight pressing down.
GET YOUR VISE HARDWARE FIRST - THEN BUILD AROUND THEM.
If you go with long threaded rods to hold the legs to the stretchers - get the Lee Valley "tension nuts" (see the black "button" looking things on the end of this lathe bench. Not that a routed dado in the back of the stretchers for the threaded rod to sit in is easier to do than drilling a really long hole through the length of the stretchers.
Unless you're blessed with a perfectly flat shop floor, and if you don't care for shimming a leg, look into leg levelers - preferably adjustable from above - with an allen wrench.
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the maxim - Buy Once, Cry Once - spend time studying what a workbench can do and pick the features that suit the type of work you do, or think you want to do - then build ONE bench that'll serve your needs 'til they pat you in the face with a shovel full of dirt and the next guy gets to benefit from your bench.
A good workbench is an often overlooked but really handy tool to have - clamps stuff, supports stuff while you work on it, a place to pound, etc..
charlie b