I repaired this modern-styled mantel clock. Seth Thomas made it and sold it under the “Plymouth” name. The movement has two numbers stamped on the back:
- 11 40 (November 1940) on left rear movement leg;
- 4506 (the model number) on strike hammer bridge.
The case is 8 5/8 inches tall and 12 3/4 inches wide. The dial is silver plated brass, with printed numerals, etc. The minute hand is 2 1/2 inches long from center to tip. The hands and hand nut are silver-plated. The minute track is 5 inches outside diameter. The movement runs over 8 days on a winding and strikes the hours and half hour on 2 chime rods.
This clock has Seth Thomas’s later type of mantel clock movement (the one that replaced the No. 89). In the past, I didn’t like this movement, because it is subject to severe wear due to its overly strong mainsprings. I have discovered that it will run well with weaker mainsprings (see 1940s Seth Thomas 8 Day Time and Strike Clock Movement for another example of this movement, and Two Seth Thomas “Plymouth” Tambour Mantel Clocks, 1938 and 1940 for another example).
This movement has suffered wear (see photo of the worn bushing above). A previous repairer installed many bushings off-center. It appears that first, off-center rear mainwheel bushings were installed, then all the other bushings were installed off-center to keep gear depthing correct. I tested all the gear depths, and left the bushings off-center except for one that needed moving. The rear time second wheel pivot was rough (the surface was like a fine file), which is why there was so much wear to its bushing. I polished all the pivots and replaced a bent wire in the center pinion.
I replaced the too-strong original mainsprings with weaker ones.
- Time 11/16 x 0.0183 x 80 inches;
- Strike 11/16 x 0.018 x 80 inches.
New, thinner mainsprings:
- Time 11/16 x 0.0161 x 80 inches (Timesavers 20506 shortened by 16 inches);
- Strike 11/16 x 0.0167 x 80 inches (Empire Clock 280-17-505 shortened by 16 inches).
(Note: supplier Empire Clock is no longer in business.)
The movement runs extremely well these mainsprings, and would probably run well with even thinner springs (perhaps 0.015 inch thick for the time mainspring). Both mainwheels are 25% worn due to the original strong mainsprings. The clock runs well in spite of the tooth wear.
The pendulum bob is 1 13/16 inches diameter and weighs 4 ounces. The suspension spring is 0.004 inches thick, and the pendulum rod is 2 millimeters diameter.
The inside of the rear door has an instruction label. The label includes the following:
Guarantee and Directions
Covering Clocks equipped with
No. 4300, 4500 and 4600 Series 8-Day Pendulum
Strike Movements in Tambour Cases.
Text here about the clock
Instruction text here
The Plymouth Clock
The number 414 is stamped at the bottom.
Repair job 5534
Key: No. 6 large end, No. 0000 (4/0) small end.