A cable-driven device, such as a joint or instrument of a computer-assisted manipulator system, may comprise a capstan mechanism to wind/unwind cables. The capstan mechanism comprises a capstan that has a groove in an outer surface of the capstan to guide the cables, which are routed from a take-up pulley, to spool onto the capstan as the capstan rotates. A guide element is engaged with the groove. The guide element is held translationally stationary relative to the take-up pulley, while there is relative translation between the capstan and both the guide element and the take-up pulley. Thus, as the capstan rotates, the guide element engages with the groove and forces the capstan and the take-up pulley to translate relative to one another. This relative translation of the capstan and the take-up pulley may prevent deviation of a take-up angle of the cable as the cable spools onto the capstan.