Lay a leg flat on your work surface, with the countersink side of the thru-holes down. Stick a piece of threaded rod in each hole. Take a stretcher that is marked to have one end adjoin the top of this leg, stick a dowel center in its dowel hole, line it up against the leg, using the threaded rod for positioning, You want the top of the stretcher to be even with the top of the leg, or just slightly above it. Give the end of the stretcher a whack with your rubber mallet. This will leave a mark indicating where the matching dowel hole in the leg needs to be drilled. Repeat with the lower stretcher than adjoins this leg. Then repeat for the other leg that will form this trestle, and the other ends of the two stretchers.
If the holes of the first jaw are in the proper position, drill holes in the same locations on the other jaw. I lined the drilled jaw on top of the undrilled jaw, clamped things down, and then drilled about 1/4" into the undrilled jaw, to mark the location. Then I removed the drilled jaw and drilled out the marked locations the same way I did the first.
Before you start cutting or drilling the pieces that will make up the top, determine the layout of the top. This should include the dimensions of the MDF, the dimensions of the edging, the locations of the vises, and of the screws or bolts that will support the vises, and of all of the benchdog holes and of all of the drywall screws you will use to laminate the panels,
You may even want to put yourself in the picture. If your workshop space already exists, find a large piece of cardboard, wallboard, or plywood that’s about the size of the workbench top you envision. Find a couple of stools or chairs, perhaps a few books, and turn them into stanchions to support the “benchtop.” Is it too big for the space? Is it large enough for the tasks you envision will be performed upon it?
These sorts of things are usually glued and screwed, but it's actually the glue that holds them together - the screws just hold everything tight while the glue cures. Screwing into hardboard or 1/4" ply is an exercise in futility, so I just used glue, and used my two 4x4's as long clamps. It would have been a bit easier, if I'd done this before I'd rough-cut the 4x4's, but it worked out.
I have always wanted to share this wonderful woodworking world with like-minded people from all over the world. For the last six months, I have started sharing Japanese woodworking information through videos and photos. Because of the huge amount of interest, I started organizing one-day workshops for people visiting Kyoto, letting them experience Japanese woodworking tools.
I ended up making a number of practice cuts. The first revealed that I hadn't tightened the screws on the edge guide enough. The second revealed that the design of the edge guide provided very little support at the end of a board, because of the cut-out for the router bit. In the "Getting Started in Woodworking" video, they had screwed a piece of hardwood to the edge-guide, to provide a continuous -- and longer -- bearing surface. I may do that myself, some day, but I didn't have the materials at hand, so I clamped some 2x4 scrap to the end of each board, to provide a continuous bearing surface past the ends. The two grooves in the long stretchers and the side groove in the short stretchers have identical layout. I made practice cuts in scrap until I had the edge guide set correctly, then I cut them all with that one setting. The bottom groove of the short stretchers uses a different setup, so it was back to the scrap, before cutting them.
Synopsis: No room in the garage? Basement not an option? Consider what Ken St. Onge did when he needed shop space: He bought a prefabricated shed and converted it into his full-time woodshop. Because a pre-built shed doesn’t need a cement foundation and is built in a factory, it’s much less expensive than building an addition or stand-alone shop on your property. It can have taller ceilings than a garage and bigger doors than a basement, both big pluses for a woodworker. You can put a shed just about anywhere, too. Here’s a soup to nuts look at Ken’s experience, so you can gauge whether a shop in a shed is right for you.