Things You'll Need
Instructions
Cut the upright supports. Cut the 10-inch four-by-fours to a length of 9 feet 4 inches. Using a miter saw, angle one end with a 15-degree cut and the other with a 75-degree cut so that the short side of each cut is on the same part of the 4-by-4. This will create a swing set with a top bar height of 9 feet whose legs are about 5 feet apart from each other on each side.
Tack the 8-foot 4-by-4 between the 15-degree mitered ends of each leg support using carpenter's nails. When the structure is complete, use a drill with a bit to fit the gauge of the carriage bolt and drill a hole all the way through the outside supports and crossbar. Sink the 8-inch carriage bolts through this hole to reinforce the structure.
Cut the 8-foot two-by-four into two lengths of 2 feet 8 inches and discard the scrap. Miter both edges at 75 degrees. This forms a strut to strengthen the legs. Affix one to each leg assembly, roughly 4 feet from the ground, using a hammer and nails. When the struts are in place, reinforce the joint by drilling and sinking the four 7-inch carriage bolts into the joint.
On the underside of the crossbar, sink the four eyelet screws in pairs. Each pair should be set about 24 inches apart and 18 inches from the outer leg assembly. Attach the chain and swing seat assemblies to the eyelets.