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Many antique French clock movements are secured in the case by tension: Two screws from the back cover pull on two straps attached to the dial plate. Friction is relied upon to keep the movement secure in the case.

Sometimes the movement may rotate in the case even with the screws securely tightened. This can easily happen when winding the clock. If the movement rotates, the clock will be out of beat (not ticking evenly), and may stop or not run reliably.

One way to secure the movement is to cut 4 thin pieces of double-sided tape (such as carpet tape) and stick them to the edge of the dial pan (where the dial pan presses against the case). The movement must be taken out of the case to do this. Cut the tape to a curved, narrow shape that will not be visible when the movement is installed.

Here are two clocks I just did this to:

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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.

Related posts:

1. Strike warning wheel problems in old French Clock
2. French Quarter Hour Striking Clock
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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.

Related posts:

1. Strike warning wheel problems in old French Clock
2. Early Revere mantel clock striking too many times

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.

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