Basic bed frames consist of a set of rails that lift the box spring above the ground, allowing more convenient height plus air flow that prevents mildew and rot. Many rail frames are also wheeled to facilitate moving the bed for cleaning or simple rearrangement. Though there are many brands of king rail bed frames, most conform to the same basic design specifications.
Measure the width of your mattress. The standard width for a king bed is 76 inches by 72 inches for a California king. However, due to settling and production variance, the actual width of your mattress may be off by several inches.
Lay the side rails of your frame on the ground, parallel to each other and about the same distance apart as your bed is wide.
Unfold the hinged head and foot rails, an integral part of your side rails.
Nest the head rails together. In some models, you will lay one L-shaped rail inside the other. Some insert a square rail into the mouth of the other rail. If your model's method is not intuitive, consult your owner's manual. Attach using the hardware provided, often a bolt and wing nut.
Adjust the head rails until their combined length equals the width of your bed.
Repeat Steps 4 and 5 for the foot rails of your bed frame.
Set the center support rail in the middle of your frame, running parallel to the side rails. Attach the ends to the head and foot rails. Most models do this via a bolt and wing nut. Again, consult your owner's manual if the method isn't intuitive.
Add box spring and mattress.