Gripnail's spacing acquisition module (SAM) provides a way to retrofit coil lines with a new pinner, regardless of the vintage or condition of the coil line controller. SAM is mounted on the frame of the coil line and "reads" the edge of the metal with through-beam fiber optic sensor that detect the notches and an encoder that measures the distance between the notches. These two pieces of information are fed into a PLC which calculates the pin spacing for each duct panel. SAM Calculates pin spacing independent of parent machine controller. The Pin spacing signal is stored in the PLC until the sheet metal travels to the Power Pinner 50 pin welder or Gripnail multi-head mechanical pinner. When the sheet metal trips a part-present switch, the pinner starts its pinning sequence. SAM can calculate the correct pin spacing for flat, "L" or wrap duct sections. The machine operator need only indicate if the duct is going to be used for high low velocity air flow.