Estimating design values for two-pin moment resisting dowel joints with lower tolerance limit approach

The lower tolerance limits (LTLs) for two-pin moment-resisting dowel joints, constructed of red oak and white oak, were estimated. Dowel joints are widely used in furniture manufacturing, especially for tables and chairs. Despite numerous studies to determine the strength capacities of dowel joints, their design values have not been established. For this purpose, T-shaped edgewise dowel joints were constructed to determine their ultimate failure load capacity levels. In tolerance analysis, the k-tolerance factor changes depending on sample sizes and confidence/proportion levels. Therefore, sample sizes were determined using a modified Faulkenberry-Week method for a univariate normally distributed data set created for a pilot study, which had 30 specimens. At least 215 specimens were required to make tolerance analyses at the 99/99 confidence/proportion level. Accordingly, 220 specimens were constructed. The LTL values were obtained at the 75/75, 90/75, 75/90, 90/90, 95/90, 90/95, 95/95, 99/95, 95/99, and 99/99 confidence/proportion levels to estimate reasonable design values. The results of the study indicated that the LTL method provides a sound design value estimate for dowel joints used in furniture frames.