This Seth Thomas mantel clock from about 1910 – 1920 has an Adamantine (celluloid) wood-grain finish. The movement is marked “89” and has bim-bam striking on the hour and a single tone strike (the high note only) on the half-hour. The case is 19 7/8 inches wide and 9 1/2 inches tall. The dial is silvered brass with printed numerals and a 4 7/16 inch diameter minute track. The minute hand is 2 3/8 inches long.
I cleaned the movement, polished the pivots, and installed 13 bushings. The pendulum rod and pendulum bob were previous replacements. The clock was losing time, so I shortened the pendulum rod by 3/8 inch.
I replaced the time mainspring because it was causing wear to the mainwheel teeth. I intended to keep the original strike mainspring, but it broke after cleaning and lubrication, as I was winding it into the clamp for re-assembly. The original mainsprings have the following measurements:
Time: 3/4 wide by 0.0185 inch thick (thicker than usual for a Seth Thomas No. 89 movement)
Strike: 3/4 inch by 0.017 to 0.0172 inch thick).
The replacement mainsprings are no. 280-19-003 from Colonial Clock Co., and have the following measurements:
Time: 3/4 inch wide by 0.0158 – 0.016 inch thick by 120 inches long
Strike: 3/4 inch wide by 0.0162 inch thick by 120 inches long.
The movement is a variation on the basic No. 89 having bim-bam strike. It was made before Seth Thomas started giving different model number to variations on the basic movement.
Here is a video showing the pendulum motion and the striking:
Repair job 5640.