Abstract: A board cut-off saw apparatus 10 is described for enabling cut-off saw operator to cross cut boards along their length to obtain usable wood pieces and to remove or discard defective sections. The apparatus 10 includes a plurality of cut-off saw lines 26 with manually activated cut-off saws for cutting the boards along each line. The length of the boards and the length of the cut wood pieces are measured while the board is being cut. Each cut-off saw line has an optical measuring system extending upstream and downstream for measuring the length of the boards 12 and cut wood pieces 24, respectively. The downstream optical sensors (photo) comprise a longitudinal row of closely assembled light emitting diodes 58 for sensing the length of the wood pieces with a measurement resolution of less than 1/4 of an inch. Each cut-off saw line 26 has a sorter for sorting the wood pieces according to their measured length.