The major complaint against MDF tops is that the edges chip away very easily. We will be eliminating that problem and building wooden vise jaws at the same time. The edging is a made from some 8/4 Oak I had for another project. You can use Maple, beech, Cheery, whatever you have or suits your fancy. Oak is a bit hard but like I said that is what I have on hand. Cut your Oak into one piece 3 inches wide and 76 inches long and two pieces 3 inches wide and 24 inches long.
If you are adding the tool tray, cut the short pieces 32 inches long. Also cut a piece of 4/4 hardwood 3 inches wide and 73 inches long. You can replace one of the long pieces of Oak with a piece of 4/4 hardwood as I have done with mine. You will also need another piece of 4/4 hardwood or plywood 7 inches wide and 73 inches long.
Using the vise jaws as a guide, cut out a relief for the jaws. This will give a wood backing so cut accurately. It may take a while with careful going but the better the fit the less likely the wood will break because of a void behind. I made a template that the router runs inside of. The router bit cut the edges of the template so all that is necessary to do is set the edges on the lines. The template can be checked directly against the vise. Set the depth with a practice piece.
Now is when I deviate a little from the ideal that anyone can build this bench using my methods. The idea was to keep the needed tools to within a start up woodworking shop budget. You can mount the edging to the bench top using a spline, dowels or as I am doing, biscuits.
For a spline, cut several splines from 1/4 plywood 1 inch wide and 72 inches long. Cut a 1/4 deep groove all around the top, 1 inch below the top edge. Glue in the splines as you assemble the edging to the top.
Dowels are a good choice for a strong joint. The can be had in several sizes, fluted as shown or cut in a spiral. You can make your own using a pair of pliers to slightly crush the dowel along its length and to provide for excess glue to escape.
For Dowels, get a set of dowel points from your favorite supplier. They are cheap and very handy. In fact you should get two sets and a few extra of your most used sizes.
Drill a series of 3/8 holes all around the top about one and 2 ½ inchs from the top edge. Set however many dowel points you have in holes. Line up the apron in place and press against the dowel points. Use the marks to drill holes in the apron. Insert dowels in the holes, put the points in a couple more holes, using the first dowels as alignment press the apron against the points, drill at marks and repeat. You may want to cut the apron a bit long then trim to size when ready to mount.
I will be using dowels on the ends to illustrate how it is done. Here the points are placed in holed drilled in the back side of the left of the front apron.
Place the mating piece in place and give it a very good whack with a non maring mallet. If you do not have a non maring mallet, use a piece of scrap against the aparon and hit that with just about anything. This transfers the marks and you can drill holes exactly on center.
Place a bit of glue on the end of the dowels and drive them into place.
Biscuits have become very popular in recent years for all types of joinery. The football shapped biscuit is a product of post war Europe when housing and cabinets needed to be built very quickly. They are made of compressed Beech and expand when glued in place. I used #20s for the apron.
Mark off the biscuit positions every 4-6 inches and use a biscuit joiner to cut the slots.
Set biscuits in the slots with a bit of glue and glue the face of the apron. Here you see the biscuits in place in the front apron around the cutout for the vise
Lay the apron in place the glue and clamp everything up.
If no tool tray is planned, continue the above process around all 4 sides. I reinforced the corners with dowels but biscuits would work as well.