A weighing device is disclosed including a motor that can be used to rotate a drive head. The drive head supports a cylindrical spindle having a plurality of holes or recesses. The spindle is configured so that it can be easily removed from the rotatable drive head and placed on a load sensor that can be used for weighing the device. In use a blister strip (not shown) can be loaded onto the spindle. An evacuation unit is provided with a pair of cutting blades. The load sensor can determine a first measurement of weight when the blisters are full of powder and a second measurement of weight after the evacuation unit has been used to evacuate receptacles supported on the spindle.