Bob temperature compensation

Discussion in 'Clock Construction' started by rogerj, Oct 24, 2016.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. Phil Burman

    Phil Burman Registered User

    Mar 8, 2014
    Suffolk England
    Country Flag:
    Region Flag:
    I think a synchronome is normally 1 order of magnitude less accurate than a precision regulator, so using the expansion of the bob to provide approximately compensation for the invar rod is good enough, but the pendulum regularity will always suffer from transient temperature effects. You can only achieve temperature compensation by calculation if you know the coefficient of expansion (certificate) of your particular rod and the other pendulum materials, otherwise you have to have a means of adjusting the compensation and do it by experiment. As I said earlier a number of people seem to be finding that modern invar requires no compensation (maybe). I wouldn't worry to much about annealing and dimensional stability yet. It is probable that your off-the -shelf invar is already annealed. If do you identify dimensional stability as an issue for the level of precision you are aiming for then use quartz. This raises the question of how far shall I go towards ultimate precision. Increased precision goes hand in hand with increased cost and degree of difficulty. It is a good idea to list all parameters that influence pendulum accuracy together with the degree of influence each has and what needs to be done to eliminate the influence. Then sort the list by degree of influence. You can then get an overview of how far you want/can afford to go.

    Who or what is HJ?

  2. rogerj

    rogerj Registered User

    Dec 21, 2014
    retired broadcast engineer
    Country Flag:
    Apologies for my brevity..H.J is Frank Hope-Jones, the man who devoted 50 years in developing the Synchronome system. So far my clock appears to have equaled the timekeeping of a Synchronome and that's all I set out to achieve..Ultimate precision it will not be !..Roger

Share This Page