Seth Thomas Tambour Mantel Clock, No. 89 Movement, Thin Time Mainspring

I recently repaired this Seth Thomas tambour mantel clock from the 1930s. The high quality dial is made of brass and engraved and silvered. The clock is 19 7/16 inches wide and 9 3/8 inches tall. The minute hand has a letter “S” in its design, and the hour hand has a letter “T”. Thus, it has built in advertising for Seth Thomas! The minute hand is 2 5/16 inches long. Note that some Seth Thomas clocks from the 1860s and 1870s had earlier style “ST” hands.

Repair job 7923. I polished the pivots and installed bushings in 15 pivot holes. The interesting thing about this clock is that the original time mainspring is only 0.016 inch thick. Usually they are around 0.17 to 0.178 inch thick. Despite the thinness, the pendulum takes an excellent motion. The strike mainspring is a replacement that is 0.0178 inch thick, and 96 inches long. (Seth Thomas No. 89 mainsprings are originally 108 inches long.)

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  1. This one is around 5 to 6 ounces, but some of them have one around 3 to 4 ounces.

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