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Accurate Clock Pendulums$

Robert J. Matthys

Print publication date: 2004

Print ISBN-13: 9780198529712

Published to Oxford Scholarship Online: January 2010

DOI: 10.1093/acprof:oso/9780198529712.001.0001

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Dimensional stability of pendulum materials

Dimensional stability of pendulum materials

(p.57) Chapter 11 Dimensional stability of pendulum materials
Accurate Clock Pendulums

Robert James Matthys

Oxford University Press

The dimensional stability of a pendulum directly affects its accuracy. If the bob sags downward or warps upward, the clock slows down or speeds up. If the temperature compensator shrinks or expands in length, the same thing happens. If the pendulum rod gets longer or shorter, again the clock slows down or speeds up. It does not take much to disturb an accurate dock. Unless a pendulum is kept in a constant temperature room, it is apparent that heat treatment will improve the pendulum's stability by 2-8 times, the exact amount of improvement depending on the material. The combination of annealing plus temperature cycling is very effective in reducing the thermal hysteresis of pendulum materials, making a pendulum clock more stable and more accurate in the typical home environment where the temperature is not perfectly constant.

Keywords:   dimensional stability, pendulum, heat treatment, annealing, temperature cycling, thermal hysteresis, accuracy, pendulum materials, pendulum clock


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