More accurate methods for determining the preload rely on defining or measuring the '' screw extension '' ; for instance , measurement of the angular rotation of the nut can serve as the basis for defining screw extension based on the fastener 's thread pitch .
More accurate methods for determining the preload rely on defining or measuring the '' screw extension '' from the nut . 
 Alternatively , measurement of the angular rotation of the nut can serve as the basis for defining screw extension based on the fastener 's thread pitch .