By Robert James Matthys
The Shortt clock, made within the 1920's is the main recognized actual clock pendulum ever identified, having an accuracy of 1 moment in keeping with 12 months while saved at approximately consistent temperature. just about all of a pendulum clock's accuracy is living in its pendulum. If the pendulum is exact, the clock might be exact. during this booklet, the writer describes many clinical facets of pendulum layout and operation only with experimental information, and little arithmetic. it's been written, taking a look at the entire diversified elements and features of the pendulum in nice element, bankruptcy by way of bankruptcy, reflecting the measure of cognizance beneficial for creating a pendulum run thoroughly. the subjects lined comprise the dimensional balance of alternative pendulum fabrics, sturdy and terrible suspension spring designs, the layout of mechanical joints and clamps, impression of quartz on accuracy, temperature reimbursement, air drag of other bob shapes and making s sinusoidal electromagnetic force. One complete bankruptcy is dedicated to uncomplicated methods of bettering the accuracy of normal inexpensive pendulum clocks, that have a unique development to the dearer designs of considerably well-made ones. This e-book will turn out valuable to a person who desires to understand how to make a extra exact pendulum or pendulum clock.
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Additional resources for Accurate Clock Pendulums
In summary, on a global scale covering all types of clocks, I agree with Bateman and Woodward—long-term clock accuracy is broadly proportional to Q. But on a smaller scale, a pendulum clock scale, I agree with Leeds and Wallman: temperature and aging effects are more important than Q. Q has its place in the sun, but from a pendulum’s point of view, I believe it is a limited place, exceeded by more important issues such as temperature compensation (or control) and the dimensional stability of pendulum materials and joints.
3 was kept at 19 lb. When the bob height was changed, the bob’s diameter was also changed, so that each bob would have the same 19 lb weight. 3 shows that the permanent time error did not change much with bob height except for the tallest (12 in. 12 s for the “typical” bob with a 6 in. height. The vertical location of the bob’s internal support point also affects the permanent time error. It does so by determining whether the bob’s center of mass moves upward or downward (with respect to the bob’s support point) with increasing temperature, and with what amplitude.
This sleeve is usually quartz, but was changed to pyrex in this case. The pyrex sleeve provides about one-third of the temperature compensation. 8 in. long, that are located parallel to and on opposite sides of the quartz pendulum rod. These temperature compensating tubes are located in the plane of swing, and are supported top and bottom by stiff brass end caps. The end caps provide no temperature compensation, other than the unavoidable change in the brass’ spring constant with temperature (beam bending mode).