Measure and note the width of the spring. Divide the width by two, then add an inch. Mark the front and back nailing rails on the couch frame at this distance from each end. The first and last springs will be centered and installed at these marks.
Place a spring clip on each mark. Align the channels on the clips to the interior edges of the frame. Attach the clips to the couch frame with 1-inch upholstery tacks. Spring clips typically have one or two installation holes.
Install the first spring by sliding one end into a channel on the edge of the couch frame. Slide the other end of the spring into the corresponding clip on the opposite side of the frame. Repeat to install the spring on the opposite end of the couch frame.
Calculate the distance between the centers of the springs by adding 1 inch to the width of the springs. This distance is the needed spacing of the spring clips on the couch frame. Beginning at the center of the first installed spring clips, measure and mark the positions of the remaining spring clips on both sides of the frame.
Work from left to right to install the remaining spring clips, centered on the reference marks. Install the corresponding clips on the opposite side of the couch frame. Once all of the spring clips are tacked in place, install the couch springs by sliding the ends into the corresponding channels or grooves in the spring clips.