After gluing you'll need to clean up the plywood edges. It's awkward, but a stationary jointer works nicely. You can also use a hand plane, or a hand-held power plane.
The exposed edges are the weak part of this ply construction. They are half endgrain, of plywood filler, which tends to be cheap stuff. To fix this, saturate the edges with marine-type epoxy. I used Gudgeon Bros.West System which has the consistency of corn syrup. This stuff will soak into the edge endgrain. When it cures the once fragile edges will be the toughest part of the workbench. This will take 2 coats. The first coat soaks in and acts as a sealer. The second coat leaves a clean, durable surface. If there's voids, they can be packed with coarse sawdust between the first and second epoxy treatments.
Use one 3/8 x 4-inch bolt for each joint. The access holes are 1-inch in diameter.
I originally planned to bolt my bench to the shop floor, but once the vises were installed the bench became heavy enough to stay in place. And it's nice to be able to move it.
Attaching the bench top. Surprise! The top is simply held in place with two 1-inch diameter locater dowels that are set into the frame end aprons. The benchtop floats. Chamfer the upper edge of the protruding dowel ends. This is the same system used on the pricey LaChapelle workbench.
Clamping systems. I have several, and they are all appreciated
A 9-inch conventional woodworker's vise gets the most use. On this bench, with no overhangs, the vise must be located inboard from the legs. Use a vise that has an integral drop-down dog. You can lag screw the vise into the bottom of the workbench. I prefer to hang the vise with through bolts that have their heads in countersunk holes on the bench top.
Twin screw vise. This is a kit from Veritas. I mostly use is for working the edges Windsor chair seats and the sides or ends of my carved bowls. I added some additional chain links, to make it wider than the standard installation.
Machinist vise with wood jaw inserts. Welsh chairmaker John Brown got me into using one. Very useful for carving small stuff, sharpening, and many unexpected tasks. It's secured with just three bolts so it can be removed in a few moments. I used an old Record machinist vise that doesn't pivot. I also like the Chinese machinist vises that rotate as well as pivot. Wilton has a nice model that isn't too heavy to move around.
Dog hole system. Round dogs aren't traditional, but they work nicely. Veritas makes them from soft brass, in several lengths. The dogs are comparatively inexpensive. But the best thing about this system is that they use easily made 3/4-inch round holes. The Veritas dogs are just slightly less than 3/4-inch in diameter, and they have a little spring that keeps them in place.
Drill 3/4-inch dog holes in line with the built-in dog of the woodworker's vise and for other uses. I have 5 holes in the outer jaw of my twin screw vise and a grid of corresponding holes in the bench top. I originally used a 5-inch spacing, but have since added some intermediate holes. After drilling, coat the holes with the marine epoxy. Again, this is to toughen up all that plywood endgrain. After the epoxy cures you may have to clean the hole surfaces with a round file.
For some projects I've found the pricy little Veritas Wonder Dogs to be useful. This is a round dog with a perpendicular screw that is useful for clamping odd shapes. (We also use these with our Bowl Dogs, the massive devices for holding a half log during adzing. Bowl dogs were discussed in previous e-newsletters.) The fact that the Wonder Dogs pivot is often useful, but sometimes annoying. It's also possible for the brass pressure pad to pop loose from the screw end if you are clamping at an angle. (To date, this has happened once at CW, and we were unable to re-attach it. Lee Valley sent a replacement.)
Modifications. Over the years I've made two changes from the original design. 1) The closer spacing for the dog holes. 2) I often use C-clamps at the right end of the bench and the original 1-1/2-inch wide apron was often an obstruction for the lower part of a clamp. On my bench I scabbed on another piece, to make a 3-inch wide bearing surface. I would now make the end aprons from the same square material used for the legs.
Finish and care. Maybe a wipe with thinned linseed oil, or something like Watco Clear Danish. When I have excess oil on a rag after finishing a bowl I sometimes rub it out on the bench top. Makes it look nicer, that's all. About once a year I tighten up the through-bolts in the frame, if necessary.
Materials List: Drew Langsner's Chair Maker/Bowl Carver Workbench