Withdrawal capacity of pinned and unpinned round mortise and tenon furniture joints

Tests were conducted to determine the withdrawal capacity of cross-pinned round mortise and tenon joints. Tenon diameters ranged from a nominal 0.6 to 1.0 inches. Cross-pins were about one-half the diameter of the tenons. Both wood and steel cross-pins were included. Glued but unpinned joints were included to provide a basis of comparison. Joints with wood cross-pins developed about one-third the capacity of comparable glued but unpinned tenons; joints with steel cross-pins developed over one-half the capacity. Offsetting the cross-pins toward the root of the tenon increased withdrawal capacity, whereas offsetting the cross-pin toward the tip of the tenon decreased capacity. Shrink-fit techniques were found to provide a simple means of producing uniformly tight fitting joints. Shrink-fit joints produce significant levels of withdrawal capacity but likely should not be used alone without adhesives or cross-pins.