Larsen Miller is a formula used to calculate broad equivalent Thermal Effect (TE) stress relieving and tempering recipes. However, results are not precise. The purpose of this work is to determine a more exact procedure. ANOVA design of experiment was used and three supplemental variables were identified as a source of thermal effect variances added to temperature and time: ramp rate, soak time and correlation between Temperature and Soak time. It was then possible to predict the most effective process temperature and soak time necessary to produce the desired stress relief as defined by the angle position of a torsion spring. The results apply to one spring type and one configuration. More work is necessary to expand the methodology to families of parts, i.e. compression springs.