Photograph of Clodock Mill
Photograph of the bridging beam and tentering mechanism at Clodock Mill in close-up. Tentering [adjusting the gap between the millstones] is usually done by raising or lowering the entire bridging beam. Here, however, a more sophisticated arrangement uses a handwheel to turn gears [centre left] which wind a lever [bottom of the picture] up or down via a screw thread. The lever in turn moves the footstep bearing supporting the stone spindle, thus raising or lowering the runner stone. This permits the gap between the millstones [and therefore the quality of the meal] to be set with great accuracy and helps in keeping the two stones exactly parallel at all times.