Drill through four 6-foot-tall, 2-by-2-inch boards 6 inches down from the top. Use a drill bit size one size larger than the screws.
Stack two of the boards on top of each other, placing them so the holes line up. Bolt the boards together through the drilled holes. Leave the nut somewhat loose so you can move the boards in opposite directions after they are attached. Repeat for the second set of boards.
Stand one pair of boards up at the end of the vine row, with the bolted end at the top. Spread the boards apart at the bottom so they are approximately 3 feet apart. The pair of boards should resemble an A-frame. Set up the second pair of boards in the same way, placing them 5 ½ feet away from the first pair.
Set a 2-by-2-inch board across the top of the two A-frames to form a crossbar, resting the ends of the board in the V-shaped notch at the top of each A-frame pair. Lash the crossbar to each A-frame using heavy garden twine.
Lean a 1/2-inch diameter wooden dowels against the top crossbar. Space the dowels 4- to 6-inches apart down the length of the crossbar, or at the recommended spacing for the particular vine variety. Set a second set of dowels opposite the first set to form A-shaped supports down the length of the trellis. Lash the top of the dowels to the crossbar with the twine.
Plant the vines at the base of the dowels. You can plant a row of vines on either side of the support, setting one plant per dowel.