Black Dial Pierce Navigator

Restoration of another Pierce Navigator

As anyone who has invested a little time perusing this blog will know, I have a hard time passing up an affordable chronograph that is in need of some TLC and so it is that I found myself with another Pierce Navigator in less than pristine condition.

img_0597This Navigator is another large dial chronograph by Pierce SA from the late 1940’s or early 1950’s. I found it on eBay and offered the owner a reasonable sum with the intention of using the watch for parts but instead went straight for a full restoration.

The watch was purchased in non-working order as usual but upon removing the caseback I discovered the reason for the watch’s failure was simply a loose case screw in the works.

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Look closely and you’ll see the screw stuck in the escape wheel (left)

I removed the movement from the case and placed it in a movement holder for inspection. With the dial removed I could see that the movement was relatively clean with little rust damage.

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Relatively clean considering its age

The front side of the movement was a little worse for wear. The chronograph staff, pinion, and intermediate wheels were all missing and would need replacement. I also noted that the actuating push piece spring (which resets the chronograph pusher) was broken.

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There’s a few parts missing here and one broken spring (top of movement)

I rummaged up a replacement stem in order to wind the mainspring and placed the movement on the timegrapher. The reading was terrible.

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The beat error is alarming the but the gain is probably the biggest issue here

The amplitude was acceptable considering the watch needed a cleaning and lubrication but the beat error would need to be corrected and the fact that the watch was gaining four minutes a day could be a real problem.

I broke the movement down quickly and separated the parts for cleaning.

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Underneath the main plate the wheel train is quite tidy
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Ready for the L & R machine

Following a solvent bath and two rinses the parts were dried with a heat gun and laid out upon the workbench for inspection.

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It’s not so intimidating when the parts are properly organized

The base movement assembly is pretty straightforward as usual. The keyless works (winding mechanism) has the most bits and can take a while. The gear train is pretty simple.

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Reassembly of the gear train

A replacement chronograph staff, pinion, and intermediate wheel were taken from my stock of parts in order to rebuild the chronograph works. The staff needed a new clutch which I fabricated on the lathe from a rod of nylon.

I reduced the width of the rod to 2.1mm then severed the end with a graver; this would serve as the replacement clutch plate. Since the plate needs to be almost perfectly flat, I secured the severed bit to a brass plate with warm shellack then flattened the disk with a small file.

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Smoothing and reducing the height of the clutch plate

When the desired thickness was achieved, the plate was removed and a hole drilled for the chronograph staff.

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Adding a 1.0mm hole to the center of the clutch plate
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The completed replacement clutch plate
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It’s quite small!

With the clutch plate complete I was ready to rebuild the chronograph works.

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Assembly completed under the microscope

With the movement ticking away and the chronograph more or less set, I moved on to the aesthetics of the piece.

Since the hands were greatly oxidized, I polished them up with the Dremel tool. Next I mixed up some luminous compound to fill the hands. The dial is quite aged so a bit of pigment was added to the luminous compound to create a faux patina that is a little less jarring than bright white.

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Hands polished and set for painting
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A bit of pigment from my wife’s makeup provided the right tone
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I’m quite pleased with the patina

During the service I discovered that the movement ran fast and the timekeeping ability varied greatly based on the position tested (dial up, dial down, crown up, etc.). The culprit turned out to be an unbalanced balance wheel.

I confirmed this using a poising tool. The tool is set dead level and the balance wheel placed on the jeweled jaws.  A puff of air from a bellows will set the wheel spinning. If it stops in the same place every time then you know the wheel is unbalanced.

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Poising the balance wheel

I marked the side of the balance that was light and replaced the nearest screw with a heavier one from a scrapped balance wheel. The wheel was then retested on the poising tool before I reinstalled it in the movement. The result was much improved.

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This is a much better output than what I started with

Finally I returned the movement to it’s case. The case had been sent out prior to RePlateIt in Canada and I was impressed with their work. You can follow that endeavor in my previous post here.

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Quite a fine result

I must say I am quite pleased with the end result of this restoration project. This watch surely has a lot of history behind it and now probably has a bit more in front as well.

Author: RyMoeller

Amateur watchmaker who also happens to be interested in genealogy, Formula One, and the halcyon days of yore.

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