22 Geometric Dimensioning and Tolerancing Copyright Goodheart-Willcox Co., Inc. Applying positional tolerancing to the face plate allows the acceptable tolerance zone to increase in size. The diagonal of the square tolerance zone, represented by the dashed line in Example 1-18, is the greatest distance that allows variation in the center’s location. The length of this diagonal is equal to a constant of 1.414 times the tolerance of the location dimensions. The constant 1.414 is used only for dimensions toleranced equally in the X and Y axis directions, as in this example. The tolerance zone in Example 1-18 has a diagonal length of 1.414 × 0.5 = 0.707, rounded to 0.7. 14 – 0.25 = 13.75 15 – 0.25 = 14.75 0.5 0.5 15 + 0.25 = 15.25 14 + 0.25 = 14.25 Goodheart-Willcox Publisher Example 1-17. The tolerance zone produced by coordinate tolerancing is square when dimensions are toleranced equally in the X and Y axis directions. 0.5 0.5 0.7 Goodheart-Willcox Publisher Example 1-18. A close look at the tolerance zone produced by coordinate tolerancing. The length of the diagonal of a square tolerance zone is equal to a constant of 1.414 times the tolerance of the location dimensions.