a folding tool such as a knife has an implement such as a blade pivotally attached to the handle with a pivot shaft , allowing the implement to be rotated from a closed to an open position . the invention allows the diameter of the pivot shaft to be varied , thereby allowing the diameter of the shaft to be effectively increased in the area where the implement rotates about the shaft so that the shaft extends to and makes contact with the interior surface of the bore through the implement , without restricting the ability of the blade to freely rotate about the shaft , minimizing or eliminating any tendency of the implement to wiggle relative to the handle .