Timing a Mechanical Pendulum Clock
Timing a mechanical pendulum clock
Timing a mechanical pendulum clock is all about the overall pendulum length. Rarely has anything to do with the movement itself, unless the movement not geared to the proper length from the start.
A mechanical clock is easy to time providing the correct pendulum. When the pendulum is correct for that particular movement it will hang on the leader and keep approximate time.
The fine timing can be done only with the pendulum adjustment located at the very bottom. At the bottom of the bob is some adjustment threads and a nut.
To turn the nut one way raises the bob and the other lowers it. A shorter pendulum will make the clock run faster. A longer pendulum makes the clock run slower.
Fine timing the clock
If the clock is timing slow, raise the pendulum bob by turning the nut at the bottom of the bob. If the clock is fast, do the same but lower the clock's pendulum bob instead. One full turn is somewhere around 1-2 minutes a day faster or slower.
If there is no more adjustment
If the bob is all the way up and its still too slow or fast, shorten either the pendulum or the leader it hangs on to correct.A lyre pendulum that does not keep time with the bob all the way adjusted will need its length altered. It can be altered with the overall length by the pendulum itself or the leader it hangs onto.
The leader is about 5 to 7 inches long and engages with the crutch on back of the movement. The leader is the part that the pendulum top hook will mount to.
It is possible to shorten or lengthen the pendulum leader to put the clock in time range with some solder if needed. 1 3/4 inches is a good measurement to make one of these longer or shorter as needed, as this is the length of the threads at the bottom of the bob.
So it will give a full timing adjustment range all over again and can go up or down as needed.
German pendulum length CM stamp
The pendulum length is overall and not just the pendulum itself. These German units measure there pendulum lengths from the top of the movement and all the way down. This will include the suspension spring, the leader and also the pendulum itself.
This is based on a 4 1/2 inch bob diameter. Of course the larger the bob, the longer it will be beyond that CM stamp measurement.
Used to keep time, now does not
If the clock kept time in the past but now does not, it means a worn gear. The escape wheel is worn and it is advancing more than one tooth at a time.
The escape wheel alone would be hard to find, and hard to replace both. The entire movement would be disassembled to replace this worn escape wheel if there is another one found that will work.
The cost of having this done would be the same price as a new movement. There is no such thing as having a repair on a clock movement being better than a new movement.
The price would be about the same for a complete overhaul or a brand new one. First see if the clock movement is in production and available new. We do this by getting the numbers off of the back plate of the movement itself, right off of the brass. Please email and we will check the availability and quote for the new one.
If the movement is not in production anymore, then a movement restoration is the only option. You can ship the movement to Clockworks Attn Repair department for a beautiful restoration.
Mechanical Pendulum Clock Timing Issues - Conclusion
Fine timing of the clock is easy as seen. If the clock kept time in the past and now too fast, its time for a new movement and has nothing to do with the pendulum. A worn escape wheel is most likely the cause and a new unit would be less cost then a repair.
↑ Back to top
In your article on Timing a Mechanical Pendulum Clock, in the “If there is no more adjustment” section, you state that “It is possible to shorten or lengthen the pendulum leader to put the clock in time range with some solder if needed.” Can you elaborate on this? What do you mean by “with some solder?” My clock came with a 5 1/2″ leader. I just ordered two leaders from you. What advice do you have for me.
It is a note saying it is possible to chop one leader in half, add material from the other leader to make one longer.
The length can be added to the pendulum by means of the leader or the pendulum itself
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
I am stumped! I ordered and received two new leaders from you. I modified the leader to an effective length of about 1 1/2″ longer than the original 5 1/2″ leader. Now, with a leader approximately 7″ long, there is very little diffence in the speed of the clock at all! This clock is gaining about 5 seconds every minute. What am I missing?
Makes no sense. The longer the pendulum is supposed to be the slower the clock. Did you get the movement from us? The pendulum from us? Or were these something used you found? What is the CM off the movement back plate? How long is the pendulum tip to tip when off the clock? How wide is the pendulum bob?
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
Great information!! Thank you!