Regulating your Clock
Clocks with pendulums will in most cases have a knurled or square rating nut for the purpose of regulation. The rating nut is most often underneath the pendulum bob (the bob is the large weight at the bottom of the pendulum rod). The rating nut can also be in the middle of the bob. The rating nut is threaded onto the rating thread. To make the clock gain the rating nut needs to be turned towards the right or clockwise as seen from the bottom of the thread. To make the clock lose the rating nut is turned to the left or anti clockwise.
Some English bracket clocks have a rating thread, which is upside down and is secured to the centre of the pendulum bob. The thread protrudes upwards through two short flat posts on the pendulum rod. The rating nut is held between these two posts. As the thread is upside down then the rating nut has to be turned in the reverse direction. For faster, turn to the left, or clockwise as seen from the TOP of the rating thread. For slower, the rating nut is turned to the right, or anti clockwise.
French mantle clocks do not always have a rating nut and thread. In this case, the pendulum bob is clamped to the pendulum rod with a screw. For faster loosen the screw and slide the bob up the rod. For slower slide the bob down the rod.
Most French clocks have a system for fine adjustment of the rate, which takes the form of a small square which protrudes through the top of the dial, directly above 12 o'clock. The square is at the end of a rod, which at its other end is attached to a suspension block on the back plate of the movement. The suspension spring is fixed to the top of this block. Under the fixing point the spring is held between two cheeks of a threaded block. Turning the square on the front of the dial raises or lowers the cheeks, altering the acting length of the suspension spring therefore altering the rate of the clock. Turning the key to the right will make the clock gain and turning to the left will make the clock lose.
Carriage clocks have a platform escapement on the top of the movement. The top cock of the platform is usually engraved with a scale which is marked with one of the following:
- S & F (slow and fast)
- R & A (retard and advance)
- - & + (slow and fast)
Between the extremes of the scale is a steel lever known as the regulator. This is usually curved down from the platform towards the bottom of the case to enable it to be easily reached. Moving the regulator towards S,R,- will make the clock lose. Moving towards F,R,+ will make the clock gain. Mantle clocks which don't have a pendulum will usually have a platform escapement.
Please feel free to contact me for advice specific to your clock.