Grandfather Clock Pendulum Information
Grandfather Clock Pendulum Information
Grandfather clock pendulum information begins with the obvious discussion of length. The length of the pendulum on German units comes in a few CM options.
German units measure the pendulum from the top of the movement to the bottom of the nut threads.
The pendulum itself, the leader it hangs on, and the suspension spring that the leader hangs on.
All three components in centimeters make up that CM length in the drop down menu.
Pendulum length information
To know how long the actual pendulum is, subtract 15CM from the options with the pendulum length.
This will exclude the leader and suspension spring, and be the actual pendulum length from tip to tip off of the clock.
This length can vary as if a larger pendulum bob is selected, the actual length of the pendulum gets longer.
Why the CM length matters at all is because if the pendulum length is not near the CM length of the movement, the clock will not keep time.
So the gearing in the movement and the pendulum length works together to keep time around the specified CM length.
The bob width Options
A Lyre grandfather clock pendulum comes with either a 6 1/2, 8 1/2, or 10 1/2 inch bob diameters. The 'Bob' is the round disk at the bottom of the pendulum.
Moreover, the CM length on the movement will indicate the length of the pendulum from the TOP of the movement all the way down to the bottom of the pendulum nut threads.
This is an approximate length that depends on other factors such as bob diameter and weight of the pendulum.
Basically if the CM is 94CM the pendulum itself will be about 35 inches tip to tip off of the clock, and the 114CM option would put this same measurement at approximately 44 inches.
↑ Back to top
If you have a pendulum with a 10 1/2″ bob, how wide of a case do you need for a grandfather clock?
15 inches wide or more is best
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
The complete pendulum arm has come off inside my William Curtis of Exeter Grandfather clock and I can not see where or how to reattach it. Can you help.?
The pendulum is 10 cm diameter and the arm 110 cm long.
Please ask this same question with pictures by email to clockworks@clockworks.com
James Stoudenmire
30yr Clockmaker
Author of Clockworks.com
looking for parts for a Howard miller 610-447 grandfather clock- need chains and pendulum with bob.
We need the movement numbers = What is the movement number off of the back plate of the movement itself?
This information would be directly off of the back plate of the clockworks itself stamped into the brass. Please see the attached picture as a reference.
(This information will not be on any of the paperwork that may have come with the clock, nor will it be on the wood case. This number will only be on the brass back plate of the movement itself only.) This is because the manufacturer that made your clock case used many different movements for the same clock case.
Thank you !