Convertible furniture can help make the most of limited space, especially if you are trying to accommodate children. Bunk beds are a great way to save floor space by allowing you to have two beds in the space of one. Eventually, however, you may not want or need the stacked beds. Making your own convertible twin bunk beds can help solve this issue.
Cut eight corner posts, 32 inches long, from the 4-by-4 lumber. Cut eight horizontal end-rails, each 29 1/2 inches, from the 2-by-6. Cut two long-side rails, 75 1/2 inches each, from the 2-by-6.
Draw a line 3/4 inch from one long edge of each post. Measure and mark the opposite face of the post 8 inches in from either edge. Mark a point 10 inches in from either end, and a second point 13 1/2 inches from either end, on the line. Drill through the post at each of the four marked locations with a 1/4-inch drill bit.
Lay two posts parallel and 29 1/2 inches apart. Fit two of the horizontal 2-by-6 rails between each pair of posts, with the long lines to the outside and the 8-inch marks to the inside. Position the rails with the outside edges even with the 8-inch marks so that they extend horizontally between the posts, with one rail 8 inches in from either end. Make sure the face of the 2-by-6 is flush with the face of the post, 3/4 inch from the line and holes.
Clamp the posts together to hold the rails in place with two bar clamps. Drive one 6-by-5/16-inch lag bolt through each hole into the end of the 2-by-6 rails. Use a socket wrench to tighten them until the heads are flush with the sides of the posts to form the four ends for your beds.
Cut four pieces of angle iron 75 inches long using a reciprocating saw. Drill a hole every 8 inches along one face of each piece. Align them with the long 2-by-6 pieces so that the bottom corner is aligned to one long edge, with the drilled face above this. Space the angle 1/4 inch from either end. Drive one 1-1/4-inch treated deck screw through each hole in the angle iron to fasten it. Do this for all four long rails.
Mark the bed ends 3/4 inch in from each outside end at 9 and 14 1/2 inches up from the bottom and drill holes for bolts. Do this on all four posts -- for a total of four holes in each end -- to fit the long-side rails. Align the side rails with the bed ends so they are 8 inches above the ground. Drive one 6-inch bolt through each hole into the long rails, two in each end. Do this for both beds.
Measure and mark the center of the top and bottom of each corner post and drill a 1/2-inch-thick hole, 2 inches deep. Apply glue in the holes in the four tops of the posts and drive a 4-inch long by 1/2-inch-thick dowel into each hole. Allow the glue to dry. Stack the beds by positioning the holes in the bottoms of the posts of one bed on top of the dowels of the other.
Measure and mark the center of the bottom of eight 4-by-4 post top finials and drill a 1/2-inch hole, 2 inches deep in each. Fit them over the dowels of all eight posts when the beds are unstacked, and over the top four when they are stacked.
Fit bunkie boards in the frames with the edges supported by the angle iron and fit a twin-sized mattress on each. A bunkie board is the wooden frame that holds a bunk bed mattress in place and can be purchased from any bed or mattress supplier.