Pendulum length

[sparkey0151]

Hi just wondered could anyone tell me how to measure a pendulum, in reference to the cm measurements on the back of the movement, thanks in advance,


regards john

[willofiam]

Hello John, from what I understand with the "cm" length on the movement you would measure from the suspension post to the bottom of the pendulum bob. This measurement includes the suspension spring, pendulum leader and the pendulum.

[sparkey0151]

Cheers Will, i have been doing a bit of detective work and i have been informed that this measurement stamped on the back of the movement was a guide for the cabinet maker to give clearance for the pendulum? i have not been repairing clocks very long so i dont know if this is the case, but the way i see it is as you know the HERMLE movements well and by the way good job on your course, the movements of the same type are in different cases, but as i have said ive only been at this 5 mins so what would i know,
regards john

[Bernie Weishapl]

Been doing clocks now for over 30 yrs. I have never heard in all those years about the pendulum info being stamped on the clock movement for case makers but that is not to say that isn't what it was for. I know on the Hermle movements that the number above the line is the pendulum length and the number below the line is the beats per minute. I have been told that the measurement for a pendulum is from the suspension post to the bottom of the pendulum bob and also from the suspension post to the center of the pendulum bob. A quote from one of my clock books says, "As seen in this diagram, the length of the pendulum is measured from the pendulum's point of suspension to the center of mass of its bob." IMHO that is just a starting point and I generally measure to the middle of the pendulum. Once I have a starting point then I put a optical sensor on my microset timer and time the movement out.