Getting ready to screw the forms on my strongback I made of a laminate of 2 pcs of 3/4" ply and 2 pcs of 1/4" ply..I was wondering why in Nicks book he says to stretch a string across the top to get a center mark (the 2" side). Wouldnt it be easier and more exact to just measure to the center under each form?.....one inch in on a full 2" board? I understand on the 4" side due to bowing but why on the 2" side? Thanx.Andy