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How To Reset a Seth Thomas Mantle Clock

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Seth Thomas is one of the oldest American clock makers. Founded in Connecticut in 1813, the company produced a variety of large and small mechanical clocks throughout the 19th century. Seth Thomas mantel clocks, originally displayed on fireplace mantels, are shelf-top timepieces. When a Seth Thomas clock stops it must be reset.

Insert the winding key into the winding arbor of the Seth Thomas mantel clock. The winding arbor is one of the small holes on the face of the clock. The correct key should fit exactly into the winding arbor.

Turn the key gently a short distance to the right or to the left. Not all Seth Thomas mantel clocks wind in the same direction. If there is tension when you turn the key one way, then it is being wound in the wrong direction. Find the direction in which the key turns freely.

Continue turning the winding key in the proper direction. Wind the Seth Thomas mantel clock until the key becomes difficult to turn. Withdraw the winding key from the winding arbor.

Use your hand to gently move the hour hand to the correct hour. If the hour hand is difficult to move, do not force it; switch to the minute hand and use the minute hand to set both the hours and minutes.

Move the minute hand clockwise to the correct time. Never move the minute hand counterclockwise or the clock may break. If the hour hand will not move freely, continue turning the minute hand through each hour. Each time the minute hand passes the 12, it will advance the hour hand.

Use your hand to start the pendulum swinging once the Seth Thomas mantel clock has been set to the right time. The pendulum should be located in the back of the clock. The clock will not keep time if the pendulum is not moving.


Seth Tomas mantel clocks will not keep accurate time if the pendulum cannot swing freely. If the pendulum hits part of the clock when it swings, angle the clock by inserting a piece of cardboard or wood underneath part of the clock.


  • Seth Thomas mantel clocks may have to be reset when they are moved, as moving may throw the clock off balance.
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