Variable stiffness rule blade, rule employing same, and method of making same

摘要

A coilable measuring blade for coilable rules has a concavo-convex cross section which has an intermediate portion with a smaller arc and greater height extending through and beyond the normal standout length to provide greater standout length. The blade may also have an outer terminal portion of greater height to require its deflection as it enters the rule casing and thereby provide reduction of the speed with which the blade is being retracted into the casing.