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These two “Plymouth” tambour mantel clocks made by Seth Thomas came into my shop just a couple of days apart. They are similar but have different movements. Both have lively hour and half hour strike on two chime rods.

Plymouth was a name that Seth Thomas put on some clocks ca. 1930 – 1950. If anyone has details of this, please let me know.

Our first example is labeled 89IM on the movement. This is a variation on the popular No. 89 movement having hour and half-hour strike, with two hammers that simultaneously strike on two chime rods. The date code is 37-11 which represents November, 1937. The label on the back door has the date 5/21/38 (May 21, 1938) hand written on it. This is probably the date the clock was sold.

Our second example has the later Seth Thomas time and strike movement that was introduced to save on cost. It is labeled 10-40 and 4503, which could be date codes for October 1940 or March, 1945. If anyone can help me interpret these numbers, please let me know! Similar movements have been seen with model number A-200 on them. The label says:

Guarantee and Directions
Covering Clocks Equipped With
4300, 4500 and 4600 Series 8-Day Pendulum
Strike Movements in Tambour Cases

Both cases are 20 inches wide and 9 1/4 inches tall, with bezels measuring approximately 6 1/4 inches outside diameter. Both have “fake inlay” printed on the case front. Both  have aluminum dials. The older dial has embossed numerals, but the numerals on the newer dial are printed only. Both clocks have instruction labels inside the back doors and are illustrated below.

Movement Summary

• The No. 89 movement was introduced about 1900, and was made in many variations.
• It was replaced in the late 1930s or the early 1940s with the second movement shown above. This has smaller plates and gears and was probably a cost reduction. It is not as good, as it seems to need quite strong mainsprings to run well.
• In 1955, a flood badly damaged the Seth Thomas factory. They phased out movement manufacturing and began importing many movements from Germany. They used many Hermle movements.

“Adamantine” was Seth Thomas’ trademarked name for a celluloid finish over wood. Besides the mahogany color shown here, it was made in black, white, green, brown, tan and other colors. These cases are durable, and can usually be polished to look very nice. Sometimes the colors fade with age. Adamantine clocks were made from about the 1880s to the 1920s.

This beautiful mahogany Adamantine clock came into my shop recently with a broken time mainspring. Nothing too exciting about that, but I think this clock is so nice looking that I decided to show it here. I had previously repaired it 11 years ago, overhauling the movement and polishing the case and bezel.

I replaced the broken time mainspring with a Merritt’s P-1956 3/4 by .0165 by 96 inches (the original spring was 0.0172 inch thick). The pendulum takes a superb motion (almost too good) and so an even thinner mainspring would work. During my previous overhaul, I replaced the way too strong strike mainspring (an incorrect replacement) with a spring about 0.016 inch thick.

Repair job 4981.

I recently repaired this Ansonia mantel clock. The case is cast iron with black finish and enamel dial. It is 9 5/8 inches tall, and 11 inches wide at the feet.

The round 8 day movement is 3 1/4 inches in diameter with open mainsprings. It has rack and snail strike on the hour and half-hour. It has a strip recoil escapement.

I did not do a complete repair job on this movement, per customer request.  I cleaned it and replaced the strike click, which had failed. I also replaced the time mainspring, as the existing one was providing at least twice the necessary torque (it was not original). It was 7/16 x 0.018 by 60 inches, and I replaced it with 3/8 x 0.014 by 60″. A longer and thinner spring would have been even better, but not readily available.

The original strike spring is only 0.0125″ thick and is 7/16 inch wide, and 8 feet long. The original time mainspring was probably similar.

Here are movies of the rack and snail strike mechanism and the escapement.

Here is a slideshow.

Repair job 4990.

I just repaired this beautiful and impressive French mantel clock. The clock is 25 3/8 inches wide and has 2 matching candle holders. The visible escapement and black dial chapter ring are very good looking.

The only major problem with the clock was that the mainspring hook in the strike barrel had pulled out. I securely re-riveted back in place, after flattening the area around the hook, which had bulged. I also tightened the hook in the time barrel.

A common problem with French clocks is a torn hole in the outer mainspring end, but in this clock the mainspring ends were fine.

Here are videos of the escapement, and the clock striking:

Here is a slide show:

Repair job 4889.

In English case, brass plaque on back says:

London, October 17, 1877
I bought this clock of
Elkington & Co.
Edward Livingston Davis

Movement approximately 3-3/4 inch diameter

Case dimensions: 17 inches H, 14-1/2 W, 7-3/16 D

5-1/2 inch dial, silvered brass, painted numerals and time track.

Measured mainspring dimensions

T: 22.3 mm wide (7/8 inch), 0.0138 – 0.014 inch thick, 54 inches long

S: 22.5 mm wide (7/8 inch), 0.013 inch thick, 46 inches long.

The strike mainspring has been shortened, so I calculated the proper size.

Mainspring thickness formula:

L = pi (B squared – A squared) / 2 T

L = Length
B = Barrel inside radius
A = Arbor radius
T = Thickness

Time Barrel
B = 18 mm
A = 5.8 mm
Optimum calculated length: 51.3 inches
The spring was 54 inches long, it looked very old and had no problems, so it was left alone.

Strike Barrel
A = 18,9 mm
B = 6.5 mm
Optimum calculated length: 59 inches
The spring is only 46 inches long, so it must be replaced.

Looking in the R & M catalog, there were springs of .012, .0125 and .013 inches thick that looked correct for the clock. Since new spring are stronger than old springs, I chose the thinest spring, .012″. I felt that there was only a very small chance that this spring would be too weak.

I calculated the optimum length for a .012 inch thick spring: 63.9 inches.

The spring in the catalog is 7/8 inches wide, 0.012 inches thick, 61 inches long. It is shorter than optimum, but considering that a much shorter spring had worked in the clock before, and based on past experience that 8 French clocks are often designed to run around 2 weeks on a winding, I used this spring. It is being tested now, and after 9 days, the striking has not slowed down significantly.

Strike setting up: There must be only a very small run after the last hammer drops, otherwise the quarts will not be struck correctly.

My job 4353.

I just completed the overhaul of an Ansonia iron cased mantel clock (my job no. 4422). It has the common 4 pillar 8 day time and strike movement of dimensions 5 x 3-1/4 inches. In this clock, a previous repairer had replaced the srike mainspring with one that is 3/4 inches wide and .018 inches thick. The time spring was an original that is .0153 inches thick.

When assembling the movement, I put the original thin mainspring in the striking side, and for the time mainspring used a spring 3/4 inches wide x .0138 inches thick by 120 inches long (no. 77.303 from R & M Imports). This spring gives a good pendulum motion of just over twice the escape arc. It will run the clock reliably without causing excessive wear.

This note concerns a Revere A/C electric mantel clock with 60 RPM Telechron motor (yes, 60 RPM or 1 revolution per second) made in the late 1920’s. The movement is 5-3/8 inches tall and 5 inches wide and is labeled on the back:

1334428
1615664
PATENTS PENDING

REVERE CLOCK CO.
CINCINNATI O.

This movement relies on the second hand to reduce the endshake of the hour wheel. If the second hand is pushed all the way in, the rack tail will rest on the snail when the rack is released. With the second hand off, the hour wheel may move forward, and the rack tail can slide behind the snail, particularly at 1:00 and 2:00. So if you are testing the clock with the second hand off and hear it striking too many times, don’t be alarmed! Put the second hand on and all should be well.

I repaired a round French movement made ca. 1790 by Roque, Paris. It is a round time and strike movement about 3-1/2 inches in diameter. It is more delicate and looks more hand made than the typical round mass produced French movement from the mid-1800’s. After repair, the warning wheel kept getting out of synchronization with the locking wheel. Once or twice per day, the warning pinion would skip a tooth on the locking wheel, making the warning pin be in a different position when the strike train is as rest. After a while, the warning pin would end up adjacent to the warning lever, and the strike would fail to start. I re-synchronized the warning wheel, only to have the same thing happen again. The warning wheel was NOT loose on the hub, and the hub was tight on the arbor.

The arbors are very thin and delicate, and the fan fly tension seemed more than necessary. We thought that perhaps when the locking wheel is suddenly locked, the momentum of the fan fly caused enough flexing in the the locking or warning wheel arbor for a tooth to be skipped. My apprentice, John, suggested rebushing the pinion end of the warning wheel, as it was slightly loose.

First, I did the easy thing and reduced the tension of the fan fly tension spring, and the problem did not occur again until the 6th day (it had been occurring about every day). I looked closer and realized that the depthing between the locking wheel and warning pinion was very shallow, so I disassembled the movement and installed a bushing, at the same time moving the hole closer to the locking wheel.