A laboratory capper, decapper or combination capper/decapper includes a deck containing with a nest designed to hold an SBS-formatted tube storage rack, and a bit exchange magazine assembly containing one or more sets of adapter bits. The adapter bits are mounted on and unloaded from motor driven fittings, and are exchanged in order to cap or decap laboratory sample tubes or vials that have different head configurations. The bit exchange magazine assembly enables the bit to be exchanged robotically.