These battens are nailed to the long stretchers, flush with the bottom. They will support the shelf. Carefully measuring and marking out the location of the mortise for the short stretcher. Using an auger bit to bore out the waste of the mortise. This piece was very resinous, as you can see by the end grain. It kept clogging the lead screw on the bit. It smelled great though.
Paring the remaining waste to the lines. Dry fitting the base together to make any necessary adjustments. For example, this tenon is too tight in it's mortise. Using an auger to create the bore for the draw bore pegs. I drill straight through the walls of the mortise without the tenon in place. Then, I fit the tenon into the mortise and use the auger bit to mark where the hole I just bored would intersect the tenon.
Next, I find that mark on the tenon, and move the drillbit about 1/8" towards the shoulder of the tenon. (to the right, in this shot.) This causes the hole in the tenon and the hole in the mortise to be misaligned with each other. This misalignment is called "drawboring". Using a drawknife to sharpen these oak dowels to 5/8", the same dimension of the bores in the mortise+tenon. I wipe some glue on the faces of the tenons, and assemble them in the mortise.
Then, I pound in the drawbore pegs. The misalignment of the bores causes the peg to bend slightly as it passes through them. This pulls the tenon tightly into the mortise, "drawing the bore" in line. I do not apply any glue to the peg, only a coating of paraffin wax. Glue would swell the peg and risk damaging the tenon. Marking out the locations of the leg mortices in the benchtop. Using blue tape and a block plane blade, I can mark an extremely accurate dimension for the mortises. Using an electric drill with an auger bit and a 90* jig to bore out mortise waste. Chiseling out the remaining waste and paring to size. Making final adjustments to the tenons and fitting them into their mortises. The drop actually finished sinking the tenons perfectly. But just to be sure…