Lay out four 2-by-6-inch planks and cut the length of two to 6.5 feet. Cut the other two to 3.5 feet. Lay them out in a rectangle frame, and screw the ends together. Cut four more 3.5-foot 2-by-6-inch planks, place them in the frame as supports. Screw two planks 3 inches from the foot and head of the frame. Screw the last two 25 inches and 48 inches from the bed foot. You will now have a finished bed frame. Repeat this step for the bottom bed.
Cut four 65-inch long, 2-by-6-inch beams. Stand the beams on their ends to make the bunk posts. Using cartridge bolts, attach the frames to the beams. The lower bed frame will be attached about 1 foot from the floor and the top bunk will be about 4 feet from the floor. Ensure the frames are level and secure in place.
Measure from the center of one support post to the next. Cut two 2-by-4-inch planks for each side for both bunks. Screw the planks flat to the support beams, framing out the top and bottom bunk's sides. Each side will have two planks spaced 6 inches from the bottom of the frame with a 6-inch space between the two planks.
Sand the wood supports and frames until smooth. Use a wood planer to quickly level and shape the wood. Brush a thin coat of stain or paint to finish the bunk bed.