As multi-task machines have been popularized, their overall motion accuracy becomes of more importance as is on conventional machining centers, even for lathe-type machines on which only the X-axis accuracy was conventionally considered important. In this paper, we present the improvement of the overall accuracy of a multi-task machine by using the DBB method, which has been widely used to improve the overall accuracy of machining center. Experimental studies show that it is important for lathe-type multi-task machines to reduce angular errors caused by the construction of the machine. By controlling such angular errors, the target overall motion accuracy, 10μm or below, can be achieved.