As much of the millwright's work was done on site, one of the most important tasks was to ensure that the gears which transferred power from the waterwheels to the millstones engaged properly. To achieve this the gears were all driven in before the teeth were cut to shape. "Had the shaping been done beforehand the teeth would have been damaged by the blows…then there could be trouble from the outset, starting from the outset, starting with a faulty engagement which worsened until it set up a train of damaged gears".