Thanks for the replies from all you out there . The size of the holes range from 1/2 " to 1 1/2 " . I am making ribs for a wing with a 24" cord. I gang cut the ribs all 30 at once. Then I drill the holes, after that I take them out of the jig . Remove the balsa between the holes and you have fast and light wing ribs . this process takes about 2 hours. As for the weight savings the ribs weigh about 1/3 less.