How to Adjust the Pendulum on a Seth Thomas Clock

Written By
Mark Slingo
Mark Slingo
Published: Sep 13, 2011
Updated: Feb 5, 2019
2 minute read

A pendulum regulates the speed at which a pendulum clock runs. The speed at which a pendulum swings is dependent on the position of a weight in the pendulum and the length of a pendulum shaft. Seth Thomas was an American clockmaker who produced tall, mantle and other types of clocks. You can adjust the pendulum to regulate the speed in a Seth Thomas clock either on the face or using an adjustment knob on the base of the pendulum.

Things You'll Need:

Things You Will Need

  • Watch
  • Square key
  • On the Dial

    Note the time on the clock. Adjust the clock's time to match the time on your watch.

    Check the clock time at the same time on your watch one day later. Decide whether the clock is running fast or slow.

    Insert a square key into the slot below the center of the dial on the clock face. Turn the key clockwise to slow down the clock; counterclockwise to increase its speed.

    Continue to check and adjust the clock for six days.

    On the Pendulum

    Note the time on the clock. Adjust the clock's time to match the time on your watch.

    Check the clock time at the same time on your watch one day later. Decide whether the clock is running fast or slow.

    Turn the adjustment nut on the base of the pendulum clockwise to speed up the clock; counterclockwise to slow it down. One complete turn will alter the time in 24 hours by one minute.

    Advertisement

    Check the clock every day at the same time for six days to see if the clock requires more adjusting.

    Mark Slingo

    Mark Slingo has been a professional writer since 2008. His work has appeared in Forward, ScubaGlobe, Scuba Jedi, "Pattaya Mail" and other publications. Slingo has a Bachelor of Arts in politics from the University of Newcastle and a…

    Sponsored
    Our Pastimes Logo

    A destination for the avid collector and weekend hobbyist alike, Our Pastimes features articles and tips about your favorite cards and games, hobbies and more.

    Property of TechnologyAdvice. © 2026 TechnologyAdvice. All Rights Reserved

    Advertiser Disclosure: Some of the products that appear on this site are from companies from which TechnologyAdvice receives compensation. This compensation may impact how and where products appear on this site including, for example, the order in which they appear. TechnologyAdvice does not include all companies or all types of products available in the marketplace.