- The core is placed upon or within the innermost sufficient recurve.
- When the innermost sufficient recurve contains no ending ridge or rod rising as high as the shoulders of the loop, the core is placed on the shoulder of the loop farther from the delta. The exception to this rule is when both shoulders are equidistant to the delta, the core is then located on the center of the sufficient recurve (See Fig. 139).
- When the innermost sufficient revurve contains an uneven number of rods as high as the shoulders, the core is placed upon the end of the center rod whether it touches the looping ridge or not.
- When the innermost sufficient revurve contains an even number of rods rising as high as the shoulders, the core is placed upon the end of the farther one of the two center rods, the two center rods being treated as though they were connected gy a recurving ridge.
The shoulders of a loop ar ethe points at which the recurving ridge definitely turns inward or curves.
Figures 33 to 38 reflect the focal points of a series of loops. In figure 39, there are two rods, but the rod marked "A" does not rise as high as the shoulder line X, so the core is at B.
Figures 40 to 45 illustrate the rule that a recurve must have no appendage abutting upon it at a right angle between the shoulders and on the outside. If such an appendage is present between the shoulders of a loop, that loop is considered spoiled and the next loop outside will be considered to locate the core. In each of the figures, the point C indicates the core.
